{*********************************************************}
{* ZLib compression. This unit is provided as freeware   *}
{* and is written for 32-bit Delphi (D2 and higher).     *}
{*                                                       *}
{* As noted in the source, portions are copyrighted by   *}
{* the following parties:                                *}
{*   Copyright (C) 1995-98 Jean-loup Gailly & Mark Adler *}
{*   Copyright (c) 1998-00 Jacques Nomssi Nzali          *}
{*********************************************************}

(*
_____________________________________________________________________________

PASZLIB 1.0                                                   May 11th, 1998

Based on the zlib 1.1.2, a general purpose data compression library.

Copyright (C) 1998,1999,2000 by NOMSSI NZALI Jacques H. C.
[kn&n DES]
_____________________________________________________________________________

{------------------------------------------------------------------------------}
{ This unit builds on a pascal port of the zlib compression routines           }
{ by Jean-loup Gailly and Mark Adler. The original pascal port was             }
{ performed by Jacques Nomssi Nzali as contained in PasZLib which is based     }
{ on zlib 1.1.2. There are some errors in that port which have been fixed      }
{ in this version.                                                             }
{                                                                              }
{ Although most of the code in this unit is derivative, there are some         }
{ important changes (bug fixes). Nevertheless, this code is released as        }
{ freeware with the same permissions as granted by the preceding authors       }
{ (Gailly, Adler, Nzali):                                                      }
{                                                                              }
{   "This software is provided 'as-is', without any express or implied         }
{   warranty.  In no event will the authors be held liable for any damages     }
{   arising from the use of this software.                                     }
{                                                                              }
{   Permission is granted to anyone to use this software for any purpose,      }
{   including commercial applications, and to alter it and redistribute it     }
{   freely, subject to the following restrictions:                             }
{                                                                              }
{   1. The origin of this software must not be misrepresented; you must not    }
{      claim that you wrote the original software. If you use this software    }
{      in a product, an acknowledgment in the product documentation would be   }
{      appreciated but is not required.                                        }
{   2. Altered source versions must be plainly marked as such, and must not    }
{      be misrepresented as being the original software.                       }
{   3. This notice may not be removed or altered from any source               }
{      distribution."                                                          }
{                                                                              }
{ Please direct questions, comments, problems, or fixes regarding this unit    }
{ to domartin@aol.com.                                                         }
{                                                                              }
{ References:                                                                  }
{   ZLib homepage: http://www.info-zip.org/pub/infozip/zlib/                   }
{   PasZLib homepage: http://www.tu-chemnitz.de/~nomssi/paszlib.html           }
{                                                                              }
{ Version history:                                                             }
{   09/19/00  Version 1.0.                                                     }
{   10/30/00  Version 1.1. Removed Patch112 conditional directive (as in       }
{             zlib version 1.1.3 which removed the directive).                 }
{------------------------------------------------------------------------------}

{ Delphi 2 and 3 define the cardinal type as a 31-bit integer that
  is stored in 32-bits. This can result in range check errors
  during compilation. To avoid this, in D2 and D3 we'll define
  cardinal as a longint. In D4 and higher, cardinal uses all
  32-bits so special measures are not required. }
*)


{$WARNINGS OFF}
{$J+}
{$I SGDXF.INC}

unit zlibpas_sg;

interface


{$DEFINE MAX_MATCH_IS_258}
{$IFDEF DEBUG}
{$UNDEF DEBUG}
{$ENDIF}

{ Compile with -DMAXSEG_64K if the alloc function cannot allocate more
  than 64k bytes at a time (needed on systems with 16-bit int). }

{- $DEFINE MAXSEG_64K}
{$IFDEF VER70}
  {$DEFINE MAXSEG_64K}
{$ENDIF}
{$IFNDEF WIN32}
  {$DEFINE UNALIGNED_OK}  { requires SizeOf(ush) = 2 ! }
{$ENDIF}

{$UNDEF DYNAMIC_CRC_TABLE}
{$UNDEF FASTEST}
{$define patch112}        { apply patch from the zlib home page }
{ -------------------------------------------------------------------- }
{$IFDEF WIN32}
  {$DEFINE Delphi32}
  {- $DEFINE Delphi5}  { keep compiler quiet }
  {$IFDEF SGDEL_5}
  {$DEFINE Delphi5}
  {$ENDIF}
{$ENDIF}

{$IFDEF FPC}
 {$DEFINE Use32}
 {$UNDEF DPMI}
 {$UNDEF MSDOS}
 {$UNDEF UNALIGNED_OK}  { requires SizeOf(ush) = 2 ! }
 {$UNDEF MAXSEG_64K}
 {$UNDEF Delphi32}
{$ENDIF}


{
Unit ZUtil;

  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{ Type declarations }

type
  {Byte   = usigned AnsiChar;  8 bits}
  Bytef  = byte;
  charf  = byte;

{$IFDEF FPC}
  TsgInteger    = longint;
{$ELSE}
  TsgInteger    = integer;
{$ENDIF}

  intf   = TsgInteger;
{$IFDEF MSDOS}
  uInt   = Word;
{$ELSE}
  {$IFDEF FPC}
    uInt   = longint;     { 16 bits or more }
    {$INFO Cardinal}
  {$ELSE}
    uInt   = cardinal;     { 16 bits or more }
  {$ENDIF}
{$ENDIF}
  uIntf  = uInt;

  Long   = longint;
{$ifdef Delphi5}
  uLong  = Cardinal;
{$else}
  uLong  = LongInt;      { 32 bits or more }
{$endif}
  uLongf = uLong;

  voidp  = pointer;
  voidpf = voidp;
  pBytef = ^Bytef;
  pIntf  = ^intf;
  puIntf = ^uIntf;
  puLong = ^uLongf;

  ptr2int = uInt;
{ a pointer to integer casting is used to do pointer arithmetic.
  ptr2int must be an integer type and sizeof(ptr2int) must be less
  than sizeof(pointer) - Nomssi }

const
  {$IFDEF MAXSEG_64K}
  MaxMemBlock = $FFFF;
  {$ELSE}
  MaxMemBlock = MaxInt;
  {$ENDIF}

type
  zByteArray = array[0..(MaxMemBlock div SizeOf(Bytef))-1] of Bytef;
  pzByteArray = ^zByteArray;
  zIntfArray = array[0..(MaxMemBlock div SizeOf(Intf))-1] of Intf;
  pzIntfArray = ^zIntfArray;
  zuIntArray = array[0..(MaxMemBlock div SizeOf(uInt))-1] of uInt;
  PuIntArray = ^zuIntArray;

{ Type declarations - only for deflate }

  uch  = Byte;
  uchf = uch; { FAR }
  ush  = Word;
  ushf = ush;
  ulg  = LongInt;

  TsgUnsignedInt = uInt;

  pcharf = ^charf;
  puchf = ^uchf;
  pushf = ^ushf;

  zuchfArray = zByteArray;
  puchfArray = ^zuchfArray;
  zushfArray = array[0..(MaxMemBlock div SizeOf(ushf))-1] of ushf;
  pushfArray = ^zushfArray;

{ Original:
   zlib.h -- interface of the 'zlib' general purpose compression library
  version 1.1.0, Feb 24th, 1998

  Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler


  Jean-loup Gailly        Mark Adler
  jloup@gzip.org          madler@alumni.caltech.edu

  Zlib.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}


{ Compile with -DMAXSEG_64K if the alloc function cannot allocate more
  than 64k bytes at a time (needed on systems with 16-bit int). }

{ Maximum value for memLevel in deflateInit2 }
{$ifdef MAXSEG_64K}
  {$IFDEF VER70}
  const
    MAX_MEM_LEVEL = 7;
    DEF_MEM_LEVEL = MAX_MEM_LEVEL;  { default memLevel }
  {$ELSE}
  const
    MAX_MEM_LEVEL = 8;
    DEF_MEM_LEVEL = MAX_MEM_LEVEL;  { default memLevel }
  {$ENDIF}
{$else}
const
  MAX_MEM_LEVEL = 9;
  DEF_MEM_LEVEL = 8; { if MAX_MEM_LEVEL > 8 }
{$endif}

{ Maximum value for windowBits in deflateInit2 and inflateInit2 }
const
{$IFDEF VER70}
  MAX_WBITS = 14; { 32K LZ77 window }
{$ELSE}
  MAX_WBITS = 15; { 32K LZ77 window }
{$ENDIF}

{ default windowBits for decompression. MAX_WBITS is for compression only }
const
  DEF_WBITS = MAX_WBITS;

{ The memory requirements for deflate are (in bytes):
            1 shl (windowBits+2)   +  1 shl (memLevel+9)
 that is: 128K for windowBits=15  +  128K for memLevel = 8  (default values)
 plus a few kilobytes for small objects. For example, if you want to reduce
 the default memory requirements from 256K to 128K, compile with
     DMAX_WBITS=14 DMAX_MEM_LEVEL=7
 Of course this will generally degrade compression (there's no free lunch).

 The memory requirements for inflate are (in bytes) 1 shl windowBits
 that is, 32K for windowBits=15 (default value) plus a few kilobytes
 for small objects. }


{ Huffman code lookup table entry--this entry is four bytes for machines
  that have 16-bit pointers (e.g. PC's in the small or medium model). }

type
  pInflate_huft = ^inflate_huft;
  inflate_huft = Record
    Exop,             { number of extra bits or operation }
    bits : Byte;      { number of bits in this code or subcode }
    {pad : uInt;}       { pad structure to a power of 2 (4 bytes for }
                      {  16-bit, 8 bytes for 32-bit int's) }
    base : uInt;      { literal, length base, or distance base }
                      { or table offset }
  End;

type
  huft_field = Array[0..(MaxMemBlock div SizeOf(inflate_huft))-1] of inflate_huft;
  huft_ptr = ^huft_field;
type
  ppInflate_huft = ^pInflate_huft;

type
  inflate_codes_mode = ( { waiting for "i:"=input, "o:"=output, "x:"=nothing }
        START,    { x: set up for LEN }
        LEN,      { i: get length/literal/eob next }
        LENEXT,   { i: getting length extra (have base) }
        DIST,     { i: get distance next }
        DISTEXT,  { i: getting distance extra }
        COPY,     { o: copying bytes in window, waiting for space }
        LIT,      { o: got literal, waiting for output space }
        WASH,     { o: got eob, possibly still output waiting }
        ZEND,     { x: got eob and all data flushed }
        BADCODE); { x: got error }

{ inflate codes private state }
type
  pInflate_codes_state = ^inflate_codes_state;
  inflate_codes_state = record

    mode : inflate_codes_mode;        { current inflate_codes mode }

    { mode dependent information }
    len : uInt;
    sub : record                      { submode }
      Case Byte of
      0:(code : record                { if LEN or DIST, where in tree }
          tree : pInflate_huft;       { pointer into tree }
          need : uInt;                { bits needed }
         end);
      1:(lit : uInt);                 { if LIT, literal }
      2:(copy: record                 { if EXT or COPY, where and how much }
           get : uInt;                { bits to get for extra }
           dist : uInt;               { distance back to copy from }
         end);
    end;

    { mode independent information }
    lbits : Byte;                     { ltree bits decoded per branch }
    dbits : Byte;                     { dtree bits decoder per branch }
    ltree : pInflate_huft;            { literal/length/eob tree }
    dtree : pInflate_huft;            { distance tree }
  end;

type
  check_func = function(check : uLong;
                        buf : pBytef;
                        {const buf : array of byte;}
	                len : uInt) : uLong;
type
  inflate_block_mode =
     (ZTYPE,    { get type bits (3, including end bit) }
      LENS,     { get lengths for stored }
      STORED,   { processing stored block }
      TABLE,    { get table lengths }
      BTREE,    { get bit lengths tree for a dynamic block }
      DTREE,    { get length, distance trees for a dynamic block }
      CODES,    { processing fixed or dynamic block }
      DRY,      { output remaining window bytes }
      BLKDONE,  { finished last block, done }
      BLKBAD);  { got a data error--stuck here }

type
  pInflate_blocks_state = ^inflate_blocks_state;

{ inflate blocks semi-private state }
  inflate_blocks_state = record

    mode : inflate_block_mode;     { current inflate_block mode }

    { mode dependent information }
    sub : record                  { submode }
    case Byte of
    0:(left : uInt);              { if STORED, bytes left to copy }
    1:(trees : record             { if DTREE, decoding info for trees }
        table : uInt;               { table lengths (14 bits) }
        index : uInt;               { index into blens (or border) }
        blens : PuIntArray;         { bit lengths of codes }
        bb : uInt;                  { bit length tree depth }
        tb : pInflate_huft;         { bit length decoding tree }
      end);
    2:(decode : record            { if CODES, current state }
        tl : pInflate_huft;
        td : pInflate_huft;         { trees to free }
        codes : pInflate_codes_state;
      end);
    end;
    last : boolean;               { true if this block is the last block }

    { mode independent information }
    bitk : uInt;            { bits in bit buffer }
    bitb : uLong;           { bit buffer }
    hufts : huft_ptr; {pInflate_huft;}  { single malloc for tree space }
    window : pBytef;        { sliding window }
    zend : pBytef;          { one byte after sliding window }
    read : pBytef;          { window read pointer }
    write : pBytef;         { window write pointer }
    checkfn : check_func;   { check function }
    check : uLong;          { check on output }
  end;

type
  inflate_mode = (
      METHOD,   { waiting for method byte }
      FLAG,     { waiting for flag byte }
      DICT4,    { four dictionary check bytes to go }
      DICT3,    { three dictionary check bytes to go }
      DICT2,    { two dictionary check bytes to go }
      DICT1,    { one dictionary check byte to go }
      DICT0,    { waiting for inflateSetDictionary }
      BLOCKS,   { decompressing blocks }
      CHECK4,   { four check bytes to go }
      CHECK3,   { three check bytes to go }
      CHECK2,   { two check bytes to go }
      CHECK1,   { one check byte to go }
      DONE,     { finished check, done }
      BAD);     { got an error--stay here }

{ inflate private state }
type
  pInternal_state = ^internal_state; { or point to a deflate_state record }
  internal_state = record

     mode : inflate_mode;  { current inflate mode }

     { mode dependent information }
     sub : record          { submode }
       case byte of
       0:(method : uInt);  { if FLAGS, method byte }
       1:(check : record   { if CHECK, check values to compare }
           was : uLong;        { computed check value }
           need : uLong;       { stream check value }
          end);
       2:(marker : uInt);  { if BAD, inflateSync's marker bytes count }
     end;

     { mode independent information }
     nowrap : boolean;      { flag for no wrapper }
     wbits : uInt;          { log2(window size)  (8..15, defaults to 15) }
     blocks : pInflate_blocks_state;    { current inflate_blocks state }
   end;

type
  alloc_func = function(opaque : voidpf; items : uInt; size : uInt) : voidpf;
  free_func = procedure(opaque : voidpf; address : voidpf);

type
  z_streamp = ^z_stream;
  z_stream = record
    next_in : pBytef;     { next input byte }
    avail_in : uInt;      { number of bytes available at next_in }
    total_in : uLong;     { total nb of input bytes read so far }

    next_out : pBytef;    { next output byte should be put there }
    avail_out : uInt;     { remaining free space at next_out }
    total_out : uLong;    { total nb of bytes output so far }

    msg : string[255];         { last error message, '' if no error }
    state : pInternal_state; { not visible by applications }

    zalloc : alloc_func;  { used to allocate the internal state }
    zfree : free_func;    { used to free the internal state }
    opaque : voidpf;      { private data object passed to zalloc and zfree }

    data_type : TsgInteger;      { best guess about the data type: ascii or binary }
    adler : uLong;        { adler32 value of the uncompressed data }
    reserved : uLong;     { reserved for future use }
  end;


{  The application must update next_in and avail_in when avail_in has
   dropped to zero. It must update next_out and avail_out when avail_out
   has dropped to zero. The application must initialize zalloc, zfree and
   opaque before calling the init function. All other fields are set by the
   compression library and must not be updated by the application.

   The opaque value provided by the application will be passed as the first
   parameter for calls of zalloc and zfree. This can be useful for custom
   memory management. The compression library attaches no meaning to the
   opaque value.

   zalloc must return Z_NULL if there is not enough memory for the object.
   On 16-bit systems, the functions zalloc and zfree must be able to allocate
   exactly 65536 bytes, but will not be required to allocate more than this
   if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
   pointers returned by zalloc for objects of exactly 65536 bytes *must*
   have their offset normalized to zero. The default allocation function
   provided by this library ensures this (see zutil.c). To reduce memory
   requirements and avoid any allocation of 64K objects, at the expense of
   compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).

   The fields total_in and total_out can be used for statistics or
   progress reports. After compression, total_in holds the total size of
   the uncompressed data and may be saved for use in the decompressor
   (particularly if the decompressor wants to decompress everything in
   a single step). }

const  { constants }
   Z_NO_FLUSH      = 0;
   Z_PARTIAL_FLUSH = 1;
   Z_SYNC_FLUSH    = 2;
   Z_FULL_FLUSH    = 3;
   Z_FINISH        = 4;
{ Allowed flush values; see deflate() below for details }

   Z_OK            = 0;
   Z_STREAM_END    = 1;
   Z_NEED_DICT     = 2;
   Z_ERRNO         = (-1);
   Z_STREAM_ERROR  = (-2);
   Z_DATA_ERROR    = (-3);
   Z_MEM_ERROR     = (-4);
   Z_BUF_ERROR     = (-5);
   Z_VERSION_ERROR = (-6);
{ Return codes for the compression/decompression functions. Negative
  values are errors, positive values are used for special but normal events.}

   Z_NO_COMPRESSION         = 0;
   Z_BEST_SPEED             = 1;
   Z_BEST_COMPRESSION       = 9;
   Z_DEFAULT_COMPRESSION    = (-1);
{ compression levels }

   Z_FILTERED            = 1;
   Z_HUFFMAN_ONLY        = 2;
   Z_DEFAULT_STRATEGY    = 0;
{ compression strategy; see deflateInit2() below for details }

   Z_BINARY   = 0;
   Z_ASCII    = 1;
   Z_UNKNOWN  = 2;
{ Possible values of the data_type field }

   Z_DEFLATED   = 8;
{ The deflate compression method (the only one supported in this version) }

   Z_NULL  = NIL;  { for initializing zalloc, zfree, opaque }

  {$IFDEF GZIO}
var
  errno : TsgInteger;
  {$ENDIF}

        { common constants }


{ The three kinds of block type }
const
  STORED_BLOCK = 0;
  STATIC_TREES = 1;
  DYN_TREES = 2;
{ The minimum and maximum match lengths }
const
  MIN_MATCH = 3;
{$ifdef MAX_MATCH_IS_258}
  MAX_MATCH = 258;
{$else}
  MAX_MATCH = ??;    { deliberate syntax error }
{$endif}

const
  PRESET_DICT = $20; { preset dictionary flag in zlib header }


  {$IFDEF DEBUG}
  procedure Assert(cond : boolean; msg : AnsiString);
  {$ENDIF}

  procedure Trace(x : AnsiString);
  procedure Tracev(x : AnsiString);
  procedure Tracevv(x : AnsiString);
  procedure Tracevvv(x : AnsiString);
  procedure Tracec(c : boolean; x : AnsiString);
  procedure Tracecv(c : boolean; x : AnsiString);

function zlibVersion : AnsiString;
{ The application can compare zlibVersion and ZLIB_VERSION for consistency.
  If the first character differs, the library code actually used is
  not compatible with the zlib.h header file used by the application.
  This check is automatically made by deflateInit and inflateInit. }

function zError(err : TsgInteger) : AnsiString;

function ZALLOC (var strm : z_stream; items : uInt; size : uInt) : voidpf;

procedure ZFREE (var strm : z_stream; ptr : voidpf);

procedure TRY_FREE (var strm : z_stream; ptr : voidpf);

const
  ZLIB_VERSION : string[10] = '1.1.2';

const
  z_errbase = Z_NEED_DICT;
  z_errmsg : Array[0..9] of string[21] = { indexed by 2-zlib_error }
           ('need dictionary',     { Z_NEED_DICT       2  }
            'stream end',          { Z_STREAM_END      1  }
            '',                    { Z_OK              0  }
            'file error',          { Z_ERRNO         (-1) }
            'stream error',        { Z_STREAM_ERROR  (-2) }
            'data error',          { Z_DATA_ERROR    (-3) }
            'insufficient memory', { Z_MEM_ERROR     (-4) }
            'buffer error',        { Z_BUF_ERROR     (-5) }
            'incompatible version',{ Z_VERSION_ERROR (-6) }
            '');
const
  z_verbose : TsgInteger = 1;

{$IFDEF DEBUG}
procedure z_error (m : AnsiString);
{$ENDIF}

{
  crc32.c -- compute the CRC-32 of a data stream
  Copyright (C) 1995-1998 Mark Adler

  crc32.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

function crc32(crc : uLong; buf : pBytef; len : uInt) : uLong;

{  inflate.c -- zlib interface to inflate modules
   Copyright (C) 1995-1998 Mark Adler

  zInflate.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

function inflateInit(var z : z_stream) : TsgInteger;
function inflateInit_(z : z_streamp; const version : AnsiString; stream_size : TsgInteger) : TsgInteger;
function inflateInit2_(var z: z_stream; w : TsgInteger; const version : AnsiString; stream_size : TsgInteger) : TsgInteger;
function inflateInit2(var z: z_stream; windowBits : TsgInteger) : TsgInteger;
function inflateEnd(var z : z_stream) : TsgInteger;
function inflateReset(var z : z_stream) : TsgInteger;
function inflate(var z : z_stream; f : TsgInteger) : TsgInteger;
function inflateSetDictionary(var z : z_stream; dictionary : pBytef; {const array of byte} dictLength : uInt) : TsgInteger;
function inflateSync(var z : z_stream) : TsgInteger;
function inflateSyncPoint(var z : z_stream) : TsgInteger;

const
  inflate_copyright = 'inflate 1.1.2 Copyright 1995-1998 Mark Adler';

{ If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
  include such an acknowledgment, I would appreciate that you keep this
  copyright string in the executable of your product. }


{ Orginal: deflate.h -- internal compression state
           deflate.c -- compress data using the deflation algorithm
  Copyright (C) 1995-1996 Jean-loup Gailly.

  zDeflate.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

function deflateInit_(strm : z_streamp; level : TsgInteger; const version : AnsiString; stream_size : TsgInteger) : TsgInteger;
function deflateInit (var strm : z_stream; level : TsgInteger) : TsgInteger;
function deflate (var strm : z_stream; flush : TsgInteger) : TsgInteger;
function deflateInit2 (var strm : z_stream; level : TsgInteger; method : TsgInteger; windowBits : TsgInteger; memLevel : TsgInteger; strategy : TsgInteger) : TsgInteger;
function deflateSetDictionary (var strm : z_stream; dictionary : pBytef; {const bytes} dictLength : uint) : TsgInteger;
function deflateCopy (dest : z_streamp; source : z_streamp) : TsgInteger;
function deflateReset (var strm : z_stream) : TsgInteger;
function deflateParams (var strm : z_stream; level : TsgInteger; strategy : TsgInteger) : TsgInteger;
function deflateEnd (var strm : z_stream) : TsgInteger;

implementation

{ zutil.pas
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{$ifdef ver80}
  {$define Delphi16}
{$endif}
{$ifdef ver70}
  {$define HugeMem}
{$endif}
{$ifdef ver60}
  {$define HugeMem}
{$endif}

{$IFDEF CALLDOS}
uses
  WinDos;
{$ENDIF}
{$IFDEF Delphi16}
uses
  WinTypes,
  WinProcs;
{$ENDIF}
{$IFNDEF FPC}
  {$IFDEF DPMI}
  uses
    WinAPI;
  {$ENDIF}
{$ENDIF}

{$IFDEF CALLDOS}
{ reduce your application memory footprint with $M before using this }
function dosAlloc (Size : Longint) : Pointer;
var
  regs: TRegisters;
begin
  regs.bx := (Size + 15) div 16; { number of 16-bytes-paragraphs }
  regs.ah := $48;                { Allocate memory block }
  msdos(regs);
  if regs.Flags and FCarry <> 0 then
    DosAlloc := NIL
  else
    DosAlloc := Ptr(regs.ax, 0);
end;


function dosFree(P : pointer) : boolean;
var
  regs: TRegisters;
begin
  dosFree := FALSE;
  regs.bx := Seg(P^);             { segment }
  if Ofs(P) <> 0 then
    exit;
  regs.ah := $49;                { Free memory block }
  msdos(regs);
  dosFree := (regs.Flags and FCarry = 0);
end;
{$ENDIF}

type
  LH = record
    L, H : word;
  end;

{$IFDEF HugeMem}
  {$define HEAP_LIST}
{$endif}

{$IFDEF HEAP_LIST} {--- to avoid Mark and Release --- }
const
  MaxAllocEntries = 50;
type
  TMemRec = record
    orgvalue,
    value : pointer;
    size: longint;
  end;
const
  allocatedCount : 0..MaxAllocEntries = 0;
var
  allocatedList : array[0..MaxAllocEntries-1] of TMemRec;

 function NewAllocation(ptr0, ptr : pointer; memsize : longint) : boolean;
 begin
   if (allocatedCount < MaxAllocEntries) and (ptr0 <> NIL) then
   begin
     with allocatedList[allocatedCount] do
     begin
       orgvalue := ptr0;
       value := ptr;
       size := memsize;
     end;
     Inc(allocatedCount);  { we don't check for duplicate }
     NewAllocation := TRUE;
   end
   else
     NewAllocation := FALSE;
 end;
{$ENDIF}

{$IFDEF HugeMem}

{ The code below is extremely version specific to the TP 6/7 heap manager!!}
type
  PFreeRec = ^TFreeRec;
  TFreeRec = record
    next: PFreeRec;
    size: Pointer;
  end;
type
  HugePtr = voidpf;


 procedure IncPtr(var p:pointer;count:word);
 { Increments pointer }
 begin
   inc(LH(p).L,count);
   if LH(p).L < count then
     inc(LH(p).H,SelectorInc);  { $1000 }
 end;

 procedure DecPtr(var p:pointer;count:word);
 { decrements pointer }
 begin
   if count > LH(p).L then
     dec(LH(p).H,SelectorInc);
   dec(LH(p).L,Count);
 end;

 procedure IncPtrLong(var p:pointer;count:longint);
 { Increments pointer; assumes count > 0 }
 begin
   inc(LH(p).H,SelectorInc*LH(count).H);
   inc(LH(p).L,LH(Count).L);
   if LH(p).L < LH(count).L then
     inc(LH(p).H,SelectorInc);
 end;

 procedure DecPtrLong(var p:pointer;count:longint);
 { Decrements pointer; assumes count > 0 }
 begin
   if LH(count).L > LH(p).L then
     dec(LH(p).H,SelectorInc);
   dec(LH(p).L,LH(Count).L);
   dec(LH(p).H,SelectorInc*LH(Count).H);
 end;
 { The next section is for real mode only }

function Normalized(p : pointer)  : pointer;
var
  count : word;
begin
  count := LH(p).L and $FFF0;
  Normalized := Ptr(LH(p).H + (count shr 4), LH(p).L and $F);
end;

procedure FreeHuge(var p:HugePtr; size : longint);
const
  blocksize = $FFF0;
var
  block : word;
begin
  while size > 0 do
  begin
    { block := minimum(size, blocksize); }
    if size > blocksize then
      block := blocksize
    else
      block := size;

    dec(size,block);
    freemem(p,block);
    IncPtr(p,block);    { we may get ptr($xxxx, $fff8) and 31 bytes left }
    p := Normalized(p); { to free, so we must normalize }
  end;
end;

function FreeMemHuge(ptr : pointer) : boolean;
var
  i : integer; { -1..MaxAllocEntries }
begin
  FreeMemHuge := FALSE;
  i := allocatedCount - 1;
  while (i >= 0) do
  begin
    if (ptr = allocatedList[i].value) then
    begin
      with allocatedList[i] do
        FreeHuge(orgvalue, size);

      Move(allocatedList[i+1], allocatedList[i],
           SizeOf(TMemRec)*(allocatedCount - 1 - i));
      Dec(allocatedCount);
      FreeMemHuge := TRUE;
      break;
    end;
    Dec(i);
  end;
end;

procedure GetMemHuge(var p:HugePtr;memsize:Longint);
const
  blocksize = $FFF0;
var
  size : longint;
  prev,free : PFreeRec;
  save,temp : pointer;
  block : word;
begin
  p := NIL;
  { Handle the easy cases first }
  if memsize > maxavail then
    exit
  else
    if memsize <= blocksize then
    begin
      getmem(p, memsize);
      if not NewAllocation(p, p, memsize) then
      begin
        FreeMem(p, memsize);
        p := NIL;
      end;
    end
    else
    begin
      size := memsize + 15;

      { Find the block that has enough space }
      prev := PFreeRec(@freeList);
      free := prev^.next;
      while (free <> heapptr) and (ptr2int(free^.size) < size) do
      begin
        prev := free;
        free := prev^.next;
      end;

      { Now free points to a region with enough space; make it the first one and
        multiple allocations will be contiguous. }

      save := freelist;
      freelist := free;
      { In TP 6, this works; check against other heap managers }
      while size > 0 do
      begin
        { block := minimum(size, blocksize); }
        if size > blocksize then
          block := blocksize
        else
          block := size;
        dec(size,block);
        getmem(temp,block);
      end;

      { We've got what we want now; just sort things out and restore the
        free list to normal }

      p := free;
      if prev^.next <> freelist then
      begin
        prev^.next := freelist;
        freelist := save;
      end;

      if (p <> NIL) then
      begin
        { return pointer with 0 offset }
        temp := p;
        if Ofs(p^)<>0 Then
          p := Ptr(Seg(p^)+1,0);  { hack }
        if not NewAllocation(temp, p, memsize + 15) then
        begin
          FreeHuge(temp, size);
          p := NIL;
        end;
      end;

    end;
end;

{$ENDIF}

procedure zmemcpy(destp : pBytef; sourcep : pBytef; len : uInt);
begin
  Move(sourcep^, destp^, len);
end;

function zmemcmp(s1p, s2p : pBytef; len : uInt) : TsgInteger;
var
  j : uInt;
  source,
  dest : pBytef;
begin
  source := s1p;
  dest := s2p;
  for j := 0 to pred(len) do
  begin
    if (source^ <> dest^) then
    begin
      zmemcmp := 2*Ord(source^ > dest^)-1;
      exit;
    end;
    Inc(source);
    Inc(dest);
  end;
  zmemcmp := 0;
end;

procedure zmemzero(destp : pBytef; len : uInt);
begin
  FillChar(destp^, len, 0);
end;

procedure zcfree(opaque : voidpf; ptr : voidpf);
{$ifdef Delphi16}
var
  Handle : THandle;
{$endif}
{$IFDEF FPC}
var
  memsize : uint;
{$ENDIF}
begin
  {$IFDEF DPMI}
  {h :=} GlobalFreePtr(ptr);
  {$ELSE}
    {$IFDEF CALL_DOS}
    dosFree(ptr);
    {$ELSE}
      {$ifdef HugeMem}
      FreeMemHuge(ptr);
      {$else}
        {$ifdef Delphi16}
        Handle := GlobalHandle(LH(ptr).H); { HiWord(LongInt(ptr)) }
        GlobalUnLock(Handle);
        GlobalFree(Handle);
        {$else}
          {$IFDEF FPC}
          Dec(puIntf(ptr));
          memsize := puIntf(ptr)^;
          FreeMem(ptr, memsize+SizeOf(uInt));
          {$ELSE}
          FreeMem(ptr);  { Delphi 2,3,4 }
          {$ENDIF}
        {$endif}
      {$endif}
    {$ENDIF}
  {$ENDIF}
end;

function zcalloc (opaque : voidpf; items : uInt; size : uInt) : voidpf;
var
  p : voidpf;
  memsize : uLong;
{$ifdef Delphi16}
  handle : THandle;
{$endif}
begin
  memsize := uLong(items) * size;
  {$IFDEF DPMI}
  p := GlobalAllocPtr(gmem_moveable, memsize);
  {$ELSE}
    {$IFDEF CALLDOS}
    p := dosAlloc(memsize);
    {$ELSE}
      {$ifdef HugeMem}
      GetMemHuge(p, memsize);
      {$else}
        {$ifdef Delphi16}
        Handle := GlobalAlloc(HeapAllocFlags, memsize);
        p := GlobalLock(Handle);
        {$else}
          {$IFDEF FPC}
          GetMem(p, memsize+SizeOf(uInt));
          puIntf(p)^:= memsize;
          Inc(puIntf(p));
          {$ELSE}
          GetMem(p, memsize);  { Delphi: p := AllocMem(memsize); }
          {$ENDIF}
        {$endif}
      {$endif}
    {$ENDIF}
  {$ENDIF}
  zcalloc := p;
end;

{ Original:
   zlib.h -- interface of the 'zlib' general purpose compression library
  version 1.1.0, Feb 24th, 1998

  Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler


  Jean-loup Gailly        Mark Adler
  jloup@gzip.org          madler@alumni.caltech.edu

  ZLib.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}


{ Compile with -DMAXSEG_64K if the alloc function cannot allocate more
  than 64k bytes at a time (needed on systems with 16-bit int). }

function zError(err : TsgInteger) : AnsiString;
begin
  zError := z_errmsg[Z_NEED_DICT-err];
end;

function zlibVersion : AnsiString;
begin
  zlibVersion := ZLIB_VERSION;
end;

procedure z_error (m : AnsiString);
begin
  WriteLn(output, m);
  Write('Zlib - Halt...');
  ReadLn;
  Halt(1);
end;

procedure Assert(cond : boolean; msg : AnsiString);
begin
  if not cond then
    z_error(msg);
end;

procedure Trace(x : AnsiString);
begin
  WriteLn(x);
end;

procedure Tracev(x : AnsiString);
begin
 if (z_verbose>0) then
   WriteLn(x);
end;

procedure Tracevv(x : AnsiString);
begin
  if (z_verbose>1) then
    WriteLn(x);
end;

procedure Tracevvv(x : AnsiString);
begin
  if (z_verbose>2) then
    WriteLn(x);
end;

procedure Tracec(c : boolean; x : AnsiString);
begin
  if (z_verbose>0) and (c) then
    WriteLn(x);
end;

procedure Tracecv(c : boolean; x : AnsiString);
begin
  if (z_verbose>1) and c then
    WriteLn(x);
end;

function ZALLOC (var strm : z_stream; items : uInt; size : uInt) : voidpf;
begin
  ZALLOC := strm.zalloc(strm.opaque, items, size);
end;

procedure ZFREE (var strm : z_stream; ptr : voidpf);
begin
  strm.zfree(strm.opaque, ptr);
end;

procedure TRY_FREE (var strm : z_stream; ptr : voidpf);
begin
  {if @strm <> Z_NULL then}
    strm.zfree(strm.opaque, ptr);
end;

{
  adler32.c -- compute the Adler-32 checksum of a data stream
  Copyright (C) 1995-1998 Mark Adler

  Adler.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

const
  BASE = uLong(65521); { largest prime smaller than 65536 }
  {NMAX = 5552; original code with unsigned 32 bit integer }
  { NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 }
  NMAX = 3854;        { code with signed 32 bit integer }
  { NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^31-1 }
  { The penalty is the time loss in the extra MOD-calls. }


{ ========================================================================= }

function adler32(adler : uLong; buf : pBytef; len : uInt) : uLong;
var
  s1, s2 : uLong;
  k : TsgInteger;
begin
  s1 := adler and $ffff;
  s2 := (adler shr 16) and $ffff;

  if not Assigned(buf) then
  begin
    adler32 := uLong(1);
    exit;
  end;

  while (len > 0) do
  begin
    if len < NMAX then
      k := len
    else
      k := NMAX;
    Dec(len, k);
    {
    while (k >= 16) do
    begin
      DO16(buf);
      Inc(buf, 16);
      Dec(k, 16);
    end;
    if (k <> 0) then
    repeat
      Inc(s1, buf^);
      Inc(puf);
      Inc(s2, s1);
      Dec(k);
    until (k = 0);
    }
    while (k > 0) do
    begin
      Inc(s1, buf^);
      Inc(s2, s1);
      Inc(buf);
      Dec(k);
    end;
    s1 := s1 mod BASE;
    s2 := s2 mod BASE;
  end;
  adler32 := (s2 shl 16) or s1;
end;

{
  crc32.c -- compute the CRC-32 of a data stream
  Copyright (C) 1995-1998 Mark Adler

  Crc.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{$IFDEF DYNAMIC_CRC_TABLE}

{local}
const
  crc_table_empty : boolean = TRUE;
{local}
var
  crc_table : array[0..256-1] of uLongf;


{
  Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
  x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.

  Polynomials over GF(2) are represented in binary, one bit per coefficient,
  with the lowest powers in the most significant bit.  Then adding polynomials
  is just exclusive-or, and multiplying a polynomial by x is a right shift by
  one.  If we call the above polynomial p, and represent a byte as the
  polynomial q, also with the lowest power in the most significant bit (so the
  byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
  where a mod b means the remainder after dividing a by b.

  This calculation is done using the shift-register method of multiplying and
  taking the remainder.  The register is initialized to zero, and for each
  incoming bit, x^32 is added mod p to the register if the bit is a one (where
  x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
  x (which is shifting right by one and adding x^32 mod p if the bit shifted
  out is a one).  We start with the highest power (least significant bit) of
  q and repeat for all eight bits of q.

  The table is simply the CRC of all possible eight bit values.  This is all
  the information needed to generate CRC's on data a byte at a time for all
  combinations of CRC register values and incoming bytes.
}
{local}
procedure make_crc_table;
var
 c    : uLong;
 n,k  : TsgInteger;
 poly : uLong; { polynomial exclusive-or pattern }

const
 { terms of polynomial defining this crc (except x^32): }
 p: array [0..13] of Byte = (0,1,2,4,5,7,8,10,11,12,16,22,23,26);

begin
  { make exclusive-or pattern from polynomial ($EDB88320) }
  poly := Long(0);
  for n := 0 to (sizeof(p) div sizeof(Byte))-1 do
    poly := poly or (Long(1) shl (31 - p[n]));

  for n := 0 to 255 do
  begin
    c := uLong(n);
    for k := 0 to 7 do
    begin
      if (c and 1) <> 0 then
        c := poly xor (c shr 1)
      else
        c := (c shr 1);
    end;
    crc_table[n] := c;
  end;
  crc_table_empty := FALSE;
end;

{$ELSE}

{ ========================================================================
  Table of CRC-32's of all single-byte values (made by make_crc_table) }

{local}
const
  crc_table : array[0..256-1] of uLongf = (
  $00000000, $77073096, $ee0e612c, $990951ba, $076dc419,
  $706af48f, $e963a535, $9e6495a3, $0edb8832, $79dcb8a4,
  $e0d5e91e, $97d2d988, $09b64c2b, $7eb17cbd, $e7b82d07,
  $90bf1d91, $1db71064, $6ab020f2, $f3b97148, $84be41de,
  $1adad47d, $6ddde4eb, $f4d4b551, $83d385c7, $136c9856,
  $646ba8c0, $fd62f97a, $8a65c9ec, $14015c4f, $63066cd9,
  $fa0f3d63, $8d080df5, $3b6e20c8, $4c69105e, $d56041e4,
  $a2677172, $3c03e4d1, $4b04d447, $d20d85fd, $a50ab56b,
  $35b5a8fa, $42b2986c, $dbbbc9d6, $acbcf940, $32d86ce3,
  $45df5c75, $dcd60dcf, $abd13d59, $26d930ac, $51de003a,
  $c8d75180, $bfd06116, $21b4f4b5, $56b3c423, $cfba9599,
  $b8bda50f, $2802b89e, $5f058808, $c60cd9b2, $b10be924,
  $2f6f7c87, $58684c11, $c1611dab, $b6662d3d, $76dc4190,
  $01db7106, $98d220bc, $efd5102a, $71b18589, $06b6b51f,
  $9fbfe4a5, $e8b8d433, $7807c9a2, $0f00f934, $9609a88e,
  $e10e9818, $7f6a0dbb, $086d3d2d, $91646c97, $e6635c01,
  $6b6b51f4, $1c6c6162, $856530d8, $f262004e, $6c0695ed,
  $1b01a57b, $8208f4c1, $f50fc457, $65b0d9c6, $12b7e950,
  $8bbeb8ea, $fcb9887c, $62dd1ddf, $15da2d49, $8cd37cf3,
  $fbd44c65, $4db26158, $3ab551ce, $a3bc0074, $d4bb30e2,
  $4adfa541, $3dd895d7, $a4d1c46d, $d3d6f4fb, $4369e96a,
  $346ed9fc, $ad678846, $da60b8d0, $44042d73, $33031de5,
  $aa0a4c5f, $dd0d7cc9, $5005713c, $270241aa, $be0b1010,
  $c90c2086, $5768b525, $206f85b3, $b966d409, $ce61e49f,
  $5edef90e, $29d9c998, $b0d09822, $c7d7a8b4, $59b33d17,
  $2eb40d81, $b7bd5c3b, $c0ba6cad, $edb88320, $9abfb3b6,
  $03b6e20c, $74b1d29a, $ead54739, $9dd277af, $04db2615,
  $73dc1683, $e3630b12, $94643b84, $0d6d6a3e, $7a6a5aa8,
  $e40ecf0b, $9309ff9d, $0a00ae27, $7d079eb1, $f00f9344,
  $8708a3d2, $1e01f268, $6906c2fe, $f762575d, $806567cb,
  $196c3671, $6e6b06e7, $fed41b76, $89d32be0, $10da7a5a,
  $67dd4acc, $f9b9df6f, $8ebeeff9, $17b7be43, $60b08ed5,
  $d6d6a3e8, $a1d1937e, $38d8c2c4, $4fdff252, $d1bb67f1,
  $a6bc5767, $3fb506dd, $48b2364b, $d80d2bda, $af0a1b4c,
  $36034af6, $41047a60, $df60efc3, $a867df55, $316e8eef,
  $4669be79, $cb61b38c, $bc66831a, $256fd2a0, $5268e236,
  $cc0c7795, $bb0b4703, $220216b9, $5505262f, $c5ba3bbe,
  $b2bd0b28, $2bb45a92, $5cb36a04, $c2d7ffa7, $b5d0cf31,
  $2cd99e8b, $5bdeae1d, $9b64c2b0, $ec63f226, $756aa39c,
  $026d930a, $9c0906a9, $eb0e363f, $72076785, $05005713,
  $95bf4a82, $e2b87a14, $7bb12bae, $0cb61b38, $92d28e9b,
  $e5d5be0d, $7cdcefb7, $0bdbdf21, $86d3d2d4, $f1d4e242,
  $68ddb3f8, $1fda836e, $81be16cd, $f6b9265b, $6fb077e1,
  $18b74777, $88085ae6, $ff0f6a70, $66063bca, $11010b5c,
  $8f659eff, $f862ae69, $616bffd3, $166ccf45, $a00ae278,
  $d70dd2ee, $4e048354, $3903b3c2, $a7672661, $d06016f7,
  $4969474d, $3e6e77db, $aed16a4a, $d9d65adc, $40df0b66,
  $37d83bf0, $a9bcae53, $debb9ec5, $47b2cf7f, $30b5ffe9,
  $bdbdf21c, $cabac28a, $53b39330, $24b4a3a6, $bad03605,
  $cdd70693, $54de5729, $23d967bf, $b3667a2e, $c4614ab8,
  $5d681b02, $2a6f2b94, $b40bbe37, $c30c8ea1, $5a05df1b,
  $2d02ef8d);

{$ENDIF}

{ =========================================================================
  This function can be used by asm versions of crc32() }

function get_crc_table : {const} puLong;
begin
{$ifdef DYNAMIC_CRC_TABLE}
  if (crc_table_empty) then
    make_crc_table;
{$endif}
  get_crc_table :=  {const} puLong(@crc_table);
end;

{ ========================================================================= }

function crc32 (crc : uLong; buf : pBytef; len : uInt): uLong;
begin
  if (buf = Z_NULL) then
    crc32 := Long(0)
  else
  begin

{$IFDEF DYNAMIC_CRC_TABLE}
    if crc_table_empty then
      make_crc_table;
{$ENDIF}

    crc := crc xor uLong($ffffffff);
    while (len >= 8) do
    begin
      {DO8(buf)}
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);

      Dec(len, 8);
    end;
    if (len <> 0) then
    repeat
      {DO1(buf)}
      crc := crc_table[(TsgInteger(crc) xor buf^) and $ff] xor (crc shr 8);
      inc(buf);

      Dec(len);
    until (len = 0);
    crc32 := crc xor uLong($ffffffff);
  end;
end;

{ types and macros common to blocks and codes
  Copyright (C) 1995-1998 Mark Adler

   WARNING: this file should *not* be used by applications. It is
   part of the implementation of the compression library and is
   subject to change.

  infutil.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{ And'ing with mask[n] masks the lower n bits }
const
  inflate_mask : array[0..17-1] of uInt = (
    $0000,
    $0001, $0003, $0007, $000f, $001f, $003f, $007f, $00ff,
    $01ff, $03ff, $07ff, $0fff, $1fff, $3fff, $7fff, $ffff);

{ copy as much as possible from the sliding window to the output area }
function inflate_flush(var s : inflate_blocks_state;
                       var z : z_stream;
                       r : TsgInteger) : TsgInteger;
var
  n : uInt;
  p : pBytef;
  q : pBytef;
begin
  { local copies of source and destination pointers }
  p := z.next_out;
  q := s.read;

  { compute number of bytes to copy as far as end of window }
  if ptr2int(q) <= ptr2int(s.write) then
    n := uInt(ptr2int(s.write) - ptr2int(q))
  else
    n := uInt(ptr2int(s.zend) - ptr2int(q));
  if (n > z.avail_out) then
    n := z.avail_out;
  if (n <> 0) and (r = Z_BUF_ERROR) then
    r := Z_OK;

  { update counters }
  Dec(z.avail_out, n);
  Inc(z.total_out, n);


  { update check information }
  if Assigned(s.checkfn) then
  begin
    s.check := s.checkfn(s.check, q, n);
    z.adler := s.check;
  end;

  { copy as far as end of window }
  zmemcpy(p, q, n);
  Inc(p, n);
  Inc(q, n);

  { see if more to copy at beginning of window }
  if (q = s.zend) then
  begin
    { wrap pointers }
    q := s.window;
    if (s.write = s.zend) then
      s.write := s.window;

    { compute bytes to copy }
    n := uInt(ptr2int(s.write) - ptr2int(q));
    if (n > z.avail_out) then
      n := z.avail_out;
    if (n <> 0) and (r = Z_BUF_ERROR) then
      r := Z_OK;

    { update counters }
    Dec( z.avail_out, n);
    Inc( z.total_out, n);

    { update check information }
    if Assigned(s.checkfn) then
    begin
      s.check := s.checkfn(s.check, q, n);
      z.adler := s.check;
    end;

    { copy }
    zmemcpy(p, q, n);
    Inc(p, n);
    Inc(q, n);
  end;


  { update pointers }
  z.next_out := p;
  s.read := q;

  { done }
  inflate_flush := r;
end;

{
  inffast.h and
  inffast.c -- process literals and length/distance pairs fast
  Copyright (C) 1995-1998 Mark Adler

  inffast.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{ Called with number of bytes left to write in window at least 258
  (the maximum AnsiString length) and number of input bytes available
  at least ten.  The ten bytes are six bytes for the longest length/
  distance pair plus four bytes for overloading the bit buffer. }

function inflate_fast( bl : uInt;
                       bd : uInt;
                       tl : pInflate_huft;
                       td : pInflate_huft;
                      var s : inflate_blocks_state;
                      var z : z_stream) : TsgInteger;

var
  t : pInflate_huft;      { temporary pointer }
  e : uInt;               { extra bits or operation }
  b : uLong;              { bit buffer }
  k : uInt;               { bits in bit buffer }
  p : pBytef;             { input data pointer }
  n : uInt;               { bytes available there }
  q : pBytef;             { output window write pointer }
  m : uInt;               { bytes to end of window or read pointer }
  ml : uInt;              { mask for literal/length tree }
  md : uInt;              { mask for distance tree }
  c : uInt;               { bytes to copy }
  d : uInt;               { distance back to copy from }
  r : pBytef;             { copy source pointer }
begin
  { load input, output, bit values (macro LOAD) }
  p := z.next_in;
  n := z.avail_in;
  b := s.bitb;
  k := s.bitk;
  q := s.write;
  if ptr2int(q) < ptr2int(s.read) then
    m := uInt(ptr2int(s.read)-ptr2int(q)-1)
  else
    m := uInt(ptr2int(s.zend)-ptr2int(q));

  { initialize masks }
  ml := inflate_mask[bl];
  md := inflate_mask[bd];

  { do until not enough input or output space for fast loop }
  repeat                      { assume called with (m >= 258) and (n >= 10) }
    { get literal/length code }
    {GRABBITS(20);}             { max bits for literal/length code }
    while (k < 20) do
    begin
      Dec(n);
      b := b or (uLong(p^) shl k);
      Inc(p);
      Inc(k, 8);
    end;

    t := @(huft_ptr(tl)^[uInt(b) and ml]);

    e := t^.exop;
    if (e = 0) then
    begin
      {DUMPBITS(t^.bits);}
      b := b shr t^.bits;
      Dec(k, t^.bits);
     {$IFDEF DEBUG}
      if (t^.base >= $20) and (t^.base < $7f) then
        Tracevv('inflate:         * literal '+AnsiChar(t^.base))
      else
        Tracevv('inflate:         * literal '+ IntToStr(t^.base));
      {$ENDIF}
      q^ := Byte(t^.base);
      Inc(q);
      Dec(m);
      continue;
    end;
    repeat
      {DUMPBITS(t^.bits);}
      b := b shr t^.bits;
      Dec(k, t^.bits);

      if (e and 16 <> 0) then
      begin
        { get extra bits for length }
        e := e and 15;
        c := t^.base + (uInt(b) and inflate_mask[e]);
        {DUMPBITS(e);}
        b := b shr e;
        Dec(k, e);
        {$IFDEF DEBUG}
        Tracevv('inflate:         * length ' + IntToStr(c));
        {$ENDIF}
        { decode distance base of block to copy }
        {GRABBITS(15);}           { max bits for distance code }
        while (k < 15) do
        begin
          Dec(n);
          b := b or (uLong(p^) shl k);
          Inc(p);
          Inc(k, 8);
        end;

        t := @huft_ptr(td)^[uInt(b) and md];
        e := t^.exop;
        repeat
          {DUMPBITS(t^.bits);}
          b := b shr t^.bits;
          Dec(k, t^.bits);

          if (e and 16 <> 0) then
          begin
            { get extra bits to add to distance base }
            e := e and 15;
            {GRABBITS(e);}         { get extra bits (up to 13) }
            while (k < e) do
            begin
              Dec(n);
              b := b or (uLong(p^) shl k);
              Inc(p);
              Inc(k, 8);
            end;

            d := t^.base + (uInt(b) and inflate_mask[e]);
            {DUMPBITS(e);}
            b := b shr e;
            Dec(k, e);

            {$IFDEF DEBUG}
            Tracevv('inflate:         * distance '+IntToStr(d));
            {$ENDIF}
            { do the copy }
            Dec(m, c);
            if (uInt(ptr2int(q) - ptr2int(s.window)) >= d) then     { offset before dest }
            begin                                  {  just copy }
              r := q;
              Dec(r, d);
              q^ := r^;  Inc(q); Inc(r); Dec(c); { minimum count is three, }
              q^ := r^;  Inc(q); Inc(r); Dec(c); { so unroll loop a little }
            end
            else                        { else offset after destination }
            begin
              e := d - uInt(ptr2int(q) - ptr2int(s.window)); { bytes from offset to end }
              r := s.zend;
              Dec(r, e);                  { pointer to offset }
              if (c > e) then             { if source crosses, }
              begin
                Dec(c, e);                { copy to end of window }
                repeat
                  q^ := r^;
                  Inc(q);
                  Inc(r);
                  Dec(e);
                until (e=0);
                r := s.window;           { copy rest from start of window }
              end;
            end;
            repeat                       { copy all or what's left }
              q^ := r^;
              Inc(q);
              Inc(r);
              Dec(c);
            until (c = 0);
            break;
          end
          else
            if (e and 64 = 0) then
            begin
              Inc(t, t^.base + (uInt(b) and inflate_mask[e]));
              e := t^.exop;
            end
          else
          begin
            z.msg := 'invalid distance code';
            {UNGRAB}
            c := z.avail_in-n;
            if (k shr 3) < c then
              c := k shr 3;
            Inc(n, c);
            Dec(p, c);
            Dec(k, c shl 3);
            {UPDATE}
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;

            inflate_fast := Z_DATA_ERROR;
            exit;
          end;
        until FALSE;
        break;
      end;
      if (e and 64 = 0) then
      begin
         {t += t->base;
          e = (t += ((uInt)b & inflate_mask[e]))->exop;}

        Inc(t, t^.base + (uInt(b) and inflate_mask[e]));
        e := t^.exop;
        if (e = 0) then
        begin
          {DUMPBITS(t^.bits);}
          b := b shr t^.bits;
          Dec(k, t^.bits);

         {$IFDEF DEBUG}
          if (t^.base >= $20) and (t^.base < $7f) then
            Tracevv('inflate:         * literal '+AnsiChar(t^.base))
          else
            Tracevv('inflate:         * literal '+IntToStr(t^.base));
          {$ENDIF}
          q^ := Byte(t^.base);
          Inc(q);
          Dec(m);
          break;
        end;
      end
      else
        if (e and 32 <> 0) then
        begin
          {$IFDEF DEBUG}
          Tracevv('inflate:         * end of block');
          {$ENDIF}
          {UNGRAB}
          c := z.avail_in-n;
          if (k shr 3) < c then
            c := k shr 3;
          Inc(n, c);
          Dec(p, c);
          Dec(k, c shl 3);
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_fast := Z_STREAM_END;
          exit;
        end
        else
        begin
          z.msg := 'invalid literal/length code';
          {UNGRAB}
          c := z.avail_in-n;
          if (k shr 3) < c then
            c := k shr 3;
          Inc(n, c);
          Dec(p, c);
          Dec(k, c shl 3);
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_fast := Z_DATA_ERROR;
          exit;
        end;
    until FALSE;
  until (m < 258) or (n < 10);

  { not enough input or output--restore pointers and return }
  {UNGRAB}
  c := z.avail_in-n;
  if (k shr 3) < c then
    c := k shr 3;
  Inc(n, c);
  Dec(p, c);
  Dec(k, c shl 3);
  {UPDATE}
  s.bitb := b;
  s.bitk := k;
  z.avail_in := n;
  Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
  z.next_in := p;
  s.write := q;
  inflate_fast := Z_OK;
end;


{ infcodes.c -- process literals and length/distance pairs
  Copyright (C) 1995-1998 Mark Adler

  infcodes.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

function inflate_codes_new (bl : uInt;
                            bd : uInt;
                            tl : pInflate_huft;
                            td : pInflate_huft;
                            var z : z_stream): pInflate_codes_state;
var
 c : pInflate_codes_state;
begin
  c := pInflate_codes_state( ZALLOC(z,1,sizeof(inflate_codes_state)) );
  if (c <> Z_NULL) then
  begin
    c^.mode := START;
    c^.lbits := Byte(bl);
    c^.dbits := Byte(bd);
    c^.ltree := tl;
    c^.dtree := td;
    {$IFDEF DEBUG}
    Tracev('inflate:       codes new');
    {$ENDIF}
  end;
  inflate_codes_new := c;
end;


function inflate_codes(var s : inflate_blocks_state;
                       var z : z_stream;
                       r : TsgInteger) : TsgInteger;
var
  j : uInt;               { temporary storage }
  t : pInflate_huft;      { temporary pointer }
  e : uInt;               { extra bits or operation }
  b : uLong;              { bit buffer }
  k : uInt;               { bits in bit buffer }
  p : pBytef;             { input data pointer }
  n : uInt;               { bytes available there }
  q : pBytef;             { output window write pointer }
  m : uInt;               { bytes to end of window or read pointer }
  f : pBytef;             { pointer to copy strings from }
var
  c : pInflate_codes_state;
begin
  c := s.sub.decode.codes;  { codes state }

  { copy input/output information to locals }
  p := z.next_in;
  n := z.avail_in;
  b := s.bitb;
  k := s.bitk;
  q := s.write;
  if ptr2int(q) < ptr2int(s.read) then
    m := uInt(ptr2int(s.read)-ptr2int(q)-1)
  else
    m := uInt(ptr2int(s.zend)-ptr2int(q));

  { process input and output based on current state }
  while True do
  case (c^.mode) of
    { waiting for "i:"=input, "o:"=output, "x:"=nothing }
  START:         { x: set up for LEN }
    begin
{$ifndef SLOW}
      if (m >= 258) and (n >= 10) then
      begin
        {UPDATE}
        s.bitb := b;
        s.bitk := k;
        z.avail_in := n;
        Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
        z.next_in := p;
        s.write := q;

        r := inflate_fast(c^.lbits, c^.dbits, c^.ltree, c^.dtree, s, z);
        {LOAD}
        p := z.next_in;
        n := z.avail_in;
        b := s.bitb;
        k := s.bitk;
        q := s.write;
        if ptr2int(q) < ptr2int(s.read) then
          m := uInt(ptr2int(s.read)-ptr2int(q)-1)
        else
          m := uInt(ptr2int(s.zend)-ptr2int(q));

        if (r <> Z_OK) then
        begin
          if (r = Z_STREAM_END) then
            c^.mode := WASH
          else
            c^.mode := BADCODE;
          continue;    { break for switch-statement in C }
        end;
      end;
{$endif} { not SLOW }
      c^.sub.code.need := c^.lbits;
      c^.sub.code.tree := c^.ltree;
      c^.mode := LEN;  { falltrough }
    end;
  LEN:           { i: get length/literal/eob next }
    begin
      j := c^.sub.code.need;
      {NEEDBITS(j);}
      while (k < j) do
      begin
        {NEEDBYTE;}
        if (n <> 0) then
          r :=Z_OK
        else
        begin
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_codes := inflate_flush(s,z,r);
          exit;
        end;
        Dec(n);
        b := b or (uLong(p^) shl k);
        Inc(p);
        Inc(k, 8);
      end;
      t := c^.sub.code.tree;
      Inc(t, uInt(b) and inflate_mask[j]);
      {DUMPBITS(t^.bits);}
      b := b shr t^.bits;
      Dec(k, t^.bits);

      e := uInt(t^.exop);
      if (e = 0) then            { literal }
      begin
        c^.sub.lit := t^.base;
       {$IFDEF DEBUG}
        if (t^.base >= $20) and (t^.base < $7f) then
          Tracevv('inflate:         literal '+AnsiChar(t^.base))
        else
          Tracevv('inflate:         literal '+IntToStr(t^.base));
        {$ENDIF}
        c^.mode := LIT;
        continue;  { break switch statement }
      end;
      if (e and 16 <> 0) then            { length }
      begin
        c^.sub.copy.get := e and 15;
        c^.len := t^.base;
        c^.mode := LENEXT;
        continue;         { break C-switch statement }
      end;
      if (e and 64 = 0) then             { next table }
      begin
        c^.sub.code.need := e;
        c^.sub.code.tree := @huft_ptr(t)^[t^.base];
        continue;         { break C-switch statement }
      end;
      if (e and 32 <> 0) then            { end of block }
      begin
        {$IFDEF DEBUG}
        Tracevv('inflate:         end of block');
        {$ENDIF}
        c^.mode := WASH;
        continue;         { break C-switch statement }
      end;
      c^.mode := BADCODE;        { invalid code }
      z.msg := 'invalid literal/length code';
      r := Z_DATA_ERROR;
      {UPDATE}
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_codes := inflate_flush(s,z,r);
      exit;
    end;
  LENEXT:        { i: getting length extra (have base) }
    begin
      j := c^.sub.copy.get;
      {NEEDBITS(j);}
      while (k < j) do
      begin
        {NEEDBYTE;}
        if (n <> 0) then
          r :=Z_OK
        else
        begin
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_codes := inflate_flush(s,z,r);
          exit;
        end;
        Dec(n);
        b := b or (uLong(p^) shl k);
        Inc(p);
        Inc(k, 8);
      end;
      Inc(c^.len, uInt(b and inflate_mask[j]));
      {DUMPBITS(j);}
      b := b shr j;
      Dec(k, j);

      c^.sub.code.need := c^.dbits;
      c^.sub.code.tree := c^.dtree;
      {$IFDEF DEBUG}
      Tracevv('inflate:         length '+IntToStr(c^.len));
      {$ENDIF}
      c^.mode := DIST;
      { falltrough }
    end;
  DIST:          { i: get distance next }
    begin
      j := c^.sub.code.need;
      {NEEDBITS(j);}
      while (k < j) do
      begin
        {NEEDBYTE;}
        if (n <> 0) then
          r :=Z_OK
        else
        begin
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_codes := inflate_flush(s,z,r);
          exit;
        end;
        Dec(n);
        b := b or (uLong(p^) shl k);
        Inc(p);
        Inc(k, 8);
      end;
      t := @huft_ptr(c^.sub.code.tree)^[uInt(b) and inflate_mask[j]];
      {DUMPBITS(t^.bits);}
      b := b shr t^.bits;
      Dec(k, t^.bits);

      e := uInt(t^.exop);
      if (e and 16 <> 0) then            { distance }
      begin
        c^.sub.copy.get := e and 15;
        c^.sub.copy.dist := t^.base;
        c^.mode := DISTEXT;
        continue;     { break C-switch statement }
      end;
      if (e and 64 = 0) then     { next table }
      begin
        c^.sub.code.need := e;
        c^.sub.code.tree := @huft_ptr(t)^[t^.base];
        continue;     { break C-switch statement }
      end;
      c^.mode := BADCODE;        { invalid code }
      z.msg := 'invalid distance code';
      r := Z_DATA_ERROR;
      {UPDATE}
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_codes := inflate_flush(s,z,r);
      exit;
    end;
  DISTEXT:       { i: getting distance extra }
    begin
      j := c^.sub.copy.get;
      {NEEDBITS(j);}
      while (k < j) do
      begin
        {NEEDBYTE;}
        if (n <> 0) then
          r :=Z_OK
        else
        begin
          {UPDATE}
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_codes := inflate_flush(s,z,r);
          exit;
        end;
        Dec(n);
        try
        b := b or (uLong(p^) shl k);
        except
          b := b + 1;
        end;
        Inc(p);
        Inc(k, 8);
      end;
      Inc(c^.sub.copy.dist, uInt(b) and inflate_mask[j]);
      {DUMPBITS(j);}
      b := b shr j;
      Dec(k, j);
      {$IFDEF DEBUG}
      Tracevv('inflate:         distance '+ IntToStr(c^.sub.copy.dist));
      {$ENDIF}
      c^.mode := COPY;
      { falltrough }
    end;
  COPY:          { o: copying bytes in window, waiting for space }
    begin
      f := q;
      Dec(f, c^.sub.copy.dist);
      if (uInt(ptr2int(q) - ptr2int(s.window)) < c^.sub.copy.dist) then
      begin
        f := s.zend;
        Dec(f, c^.sub.copy.dist - uInt(ptr2int(q) - ptr2int(s.window)));
      end;

      while (c^.len <> 0) do
      begin
        {NEEDOUT}
        if (m = 0) then
        begin
          {WRAP}
          if (q = s.zend) and (s.read <> s.window) then
          begin
            q := s.window;
            if ptr2int(q) < ptr2int(s.read) then
              m := uInt(ptr2int(s.read)-ptr2int(q)-1)
            else
              m := uInt(ptr2int(s.zend)-ptr2int(q));
          end;

          if (m = 0) then
          begin
            {FLUSH}
            s.write := q;
            r := inflate_flush(s,z,r);
            q := s.write;
            if ptr2int(q) < ptr2int(s.read) then
              m := uInt(ptr2int(s.read)-ptr2int(q)-1)
            else
              m := uInt(ptr2int(s.zend)-ptr2int(q));

            {WRAP}
            if (q = s.zend) and (s.read <> s.window) then
            begin
              q := s.window;
              if ptr2int(q) < ptr2int(s.read) then
                m := uInt(ptr2int(s.read)-ptr2int(q)-1)
              else
                m := uInt(ptr2int(s.zend)-ptr2int(q));
            end;

            if (m = 0) then
            begin
              {UPDATE}
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_codes := inflate_flush(s,z,r);
              exit;
            end;
          end;
        end;
        r := Z_OK;

        {OUTBYTE( *f++)}
        q^ := f^;
        Inc(q);
        Inc(f);
        Dec(m);

        if (f = s.zend) then
          f := s.window;
        Dec(c^.len);
      end;
      c^.mode := START;
      { C-switch break; not needed }
    end;
  LIT:           { o: got literal, waiting for output space }
    begin
      {NEEDOUT}
      if (m = 0) then
      begin
        {WRAP}
        if (q = s.zend) and (s.read <> s.window) then
        begin
          q := s.window;
          if ptr2int(q) < ptr2int(s.read) then
            m := uInt(ptr2int(s.read)-ptr2int(q)-1)
          else
            m := uInt(ptr2int(s.zend)-ptr2int(q));
        end;

        if (m = 0) then
        begin
          {FLUSH}
          s.write := q;
          r := inflate_flush(s,z,r);
          q := s.write;
          if ptr2int(q) < ptr2int(s.read) then
            m := uInt(ptr2int(s.read)-ptr2int(q)-1)
          else
            m := uInt(ptr2int(s.zend)-ptr2int(q));

          {WRAP}
          if (q = s.zend) and (s.read <> s.window) then
          begin
            q := s.window;
            if ptr2int(q) < ptr2int(s.read) then
              m := uInt(ptr2int(s.read)-ptr2int(q)-1)
            else
              m := uInt(ptr2int(s.zend)-ptr2int(q));
          end;

          if (m = 0) then
          begin
            {UPDATE}
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_codes := inflate_flush(s,z,r);
            exit;
          end;
        end;
      end;
      r := Z_OK;

      {OUTBYTE(c^.sub.lit);}
      q^ := c^.sub.lit;
      Inc(q);
      Dec(m);

      c^.mode := START;
      {break;}
    end;
  WASH:          { o: got eob, possibly more output }
    begin
      {$ifdef patch112}
      if (k > 7) then           { return unused byte, if any }
      begin
        {$IFDEF DEBUG}
        Assert(k < 16, 'inflate_codes grabbed too many bytes');
        {$ENDIF}
        Dec(k, 8);
        Inc(n);
        Dec(p);                    { can always return one }
      end;
      {$endif}
      {FLUSH}
      s.write := q;
      r := inflate_flush(s,z,r);
      q := s.write;
      if ptr2int(q) < ptr2int(s.read) then
        m := uInt(ptr2int(s.read)-ptr2int(q)-1)
      else
        m := uInt(ptr2int(s.zend)-ptr2int(q));

      if (s.read <> s.write) then
      begin
        {UPDATE}
        s.bitb := b;
        s.bitk := k;
        z.avail_in := n;
        Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
        z.next_in := p;
        s.write := q;
        inflate_codes := inflate_flush(s,z,r);
        exit;
      end;
      c^.mode := ZEND;
      { falltrough }
    end;

  ZEND:
    begin
      r := Z_STREAM_END;
      {UPDATE}
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_codes := inflate_flush(s,z,r);
      exit;
    end;
  BADCODE:       { x: got error }
    begin
      r := Z_DATA_ERROR;
      {UPDATE}
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_codes := inflate_flush(s,z,r);
      exit;
    end;
  else
    begin
      r := Z_STREAM_ERROR;
      {UPDATE}
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_codes := inflate_flush(s,z,r);
      exit;
    end;
  end;
{NEED_DUMMY_RETURN - Delphi2+ dumb compilers complain without this }
  inflate_codes := Z_STREAM_ERROR;
end;


procedure inflate_codes_free(c : pInflate_codes_state;
                             var z : z_stream);
begin
  ZFREE(z, c);
  {$IFDEF DEBUG}
  Tracev('inflate:       codes free');
  {$ENDIF}
end;

{ inftrees.h -- header to use inftrees.c
  inftrees.c -- generate Huffman trees for efficient decoding
  Copyright (C) 1995-1998 Mark Adler

  inftrees.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

const
  MANY = 1440;


{$ifdef DEBUG}
var
  inflate_hufts : uInt;
{$endif}



const
{ Tables for deflate from PKZIP's appnote.txt. }
  cplens : Array [0..30] Of uInt  { Copy lengths for literal codes 257..285 }
     = (3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
        35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0);
        { actually lengths - 2; also see note #13 above about 258 }

  invalid_code = 112;

  cplext : Array [0..30] Of uInt  { Extra bits for literal codes 257..285 }
     = (0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
        3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, invalid_code, invalid_code);

  cpdist : Array [0..29] Of uInt { Copy offsets for distance codes 0..29 }
     = (1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
        257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
        8193, 12289, 16385, 24577);

  cpdext : Array [0..29] Of uInt { Extra bits for distance codes }
     = (0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
        7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
        12, 12, 13, 13);


{ If BMAX needs to be larger than 16, then h and x[] should be uLong. }
const
  BMAX = 15;         { maximum bit length of any code }

{$DEFINE USE_PTR}

function huft_build(
var b : array of uIntf;    { code lengths in bits (all assumed <= BMAX) }
    n : uInt;              { number of codes (assumed <= N_MAX) }
    s : uInt;              { number of simple-valued codes (0..s-1) }
const d : array of uIntf;  { list of base values for non-simple codes }
{ array of word }
const e : array of uIntf;  { list of extra bits for non-simple codes }
{ array of byte }
  t : ppInflate_huft;     { result: starting table }
var m : uIntf;             { maximum lookup bits, returns actual }
var hp : array of inflate_huft;  { space for trees }
var hn : uInt;             { hufts used in space }
var v : array of uIntf     { working area: values in order of bit length }
   ) : TsgInteger;
Var
  a : uInt;                     { counter for codes of length k }
  c : Array [0..BMAX] Of uInt;  { bit length count table }
  f : uInt;                     { i repeats in table every f entries }
  g : TsgInteger;                      { maximum code length }
  h : TsgInteger;                      { table level }
  i : uInt;  {register}         { counter, current code }
  j : uInt;  {register}         { counter }
  k : TsgInteger;   {register}         { number of bits in current code }
  l : TsgInteger;			{ bits per table (returned in m) }
  mask : uInt;                  { (1 shl w) - 1, to avoid cc -O bug on HP }
  p : ^uIntf; {register}        { pointer into c[], b[], or v[] }
  q : pInflate_huft;            { points to current table }
  r : inflate_huft;             { table entry for structure assignment }
  u : Array [0..BMAX-1] Of pInflate_huft; { table stack }
  w : TsgInteger;   {register}         { bits before this table = (l*h) }
  x : Array [0..BMAX] Of uInt;  { bit offsets, then code stack }
  {$IFDEF USE_PTR}
  xp : puIntf;                  { pointer into x }
  {$ELSE}
  xp : uInt;
  {$ENDIF}
  y : TsgInteger;                      { number of dummy codes added }
  z : uInt;                     { number of entries in current table }
Begin
  { Generate counts for each bit length }
  FillChar(c,SizeOf(c),0) ;     { clear c[] }

  for i := 0 to n-1 do
    Inc (c[b[i]]);              { assume all entries <= BMAX }

  If (c[0] = n) Then            { null input--all zero length codes }
  Begin
    t^ := pInflate_huft(NIL);
    m := 0 ;
    huft_build := Z_OK ;
    Exit;
  End ;

  { Find minimum and maximum length, bound [m] by those }
  l := m;
  for j:=1 To BMAX do
    if (c[j] <> 0) then
      break;
  k := j ;                      { minimum code length }
  if (uInt(l) < j) then
    l := j;
  for i := BMAX downto 1 do
    if (c[i] <> 0) then
      break ;
  g := i ;                      { maximum code length }
  if (uInt(l) > i) then
     l := i;
  m := l;

  { Adjust last length count to fill out codes, if needed }
  y := 1 shl j ;
  while (j < i) do
  begin
    Dec(y, c[j]) ;
    if (y < 0) then
    begin
      huft_build := Z_DATA_ERROR;   { bad input: more codes than bits }
      exit;
    end ;
    Inc(j) ;
    y := y shl 1
  end;
  Dec (y, c[i]) ;
  if (y < 0) then
  begin
    huft_build := Z_DATA_ERROR;     { bad input: more codes than bits }
    exit;
  end;
  Inc(c[i], y);

  { Generate starting offsets into the value table FOR each length }
  {$IFDEF USE_PTR}
  x[1] := 0;
  j := 0;

  p := @c[1];
  xp := @x[2];

  dec(i);               { note that i = g from above }
  WHILE (i > 0) DO
  BEGIN
    inc(j, p^);
    xp^ := j;
    inc(p);
    inc(xp);
    dec(i);
  END;
  {$ELSE}
  x[1] := 0;
  j := 0 ;
  for i := 1 to g do
  begin
    x[i] := j;
    Inc(j, c[i]);
  end;
  {$ENDIF}

  { Make a table of values in order of bit lengths }
  for i := 0 to n-1 do
  begin
    j := b[i];
    if (j <> 0) then
    begin
      v[ x[j] ] := i;
      Inc(x[j]);
    end;
  end;
  n := x[g];                     { set n to length of v }

  { Generate the Huffman codes and for each, make the table entries }
  i := 0 ;
  x[0] := 0 ;                   { first Huffman code is zero }
  p := Addr(v) ;                { grab values in bit order }
  h := -1 ;                     { no tables yet--level -1 }
  w := -l ;                     { bits decoded = (l*h) }

  u[0] := pInflate_huft(NIL);   { just to keep compilers happy }
  q := pInflate_huft(NIL);      { ditto }
  z := 0 ;                      { ditto }

  { go through the bit lengths (k already is bits in shortest code) }
  while (k <= g) Do
  begin
    a := c[k] ;
    while (a<>0) Do
    begin
      Dec (a) ;
      { here i is the Huffman code of length k bits for value p^ }
      { make tables up to required level }
      while (k > w + l) do
      begin

        Inc (h) ;
        Inc (w, l);              { add bits already decoded }
                                 { previous table always l bits }
        { compute minimum size table less than or equal to l bits }

        { table size upper limit }
        z := g - w;
        If (z > uInt(l)) Then
          z := l;

        { try a k-w bit table }
        j := k - w;
        f := 1 shl j;
        if (f > a+1) Then        { too few codes for k-w bit table }
        begin
          Dec(f, a+1);           { deduct codes from patterns left }
          {$IFDEF USE_PTR}
          xp := Addr(c[k]);

          if (j < z) then
          begin
            Inc(j);
            while (j < z) do
            begin                { try smaller tables up to z bits }
              f := f shl 1;
              Inc (xp) ;
              If (f <= xp^) Then
                break;           { enough codes to use up j bits }
              Dec(f, xp^);       { else deduct codes from patterns }
              Inc(j);
            end;
          end;
          {$ELSE}
          xp := k;

          if (j < z) then
          begin
            Inc (j) ;
            While (j < z) Do
            begin                 { try smaller tables up to z bits }
              f := f * 2;
              Inc (xp) ;
              if (f <= c[xp]) then
                Break ;           { enough codes to use up j bits }
              Dec (f, c[xp]) ;      { else deduct codes from patterns }
              Inc (j);
            end;
          end;
          {$ENDIF}
        end;

        z := 1 shl j;            { table entries for j-bit table }

        { allocate new table }
        if (hn + z > MANY) then { (note: doesn't matter for fixed) }
        begin
          huft_build := Z_MEM_ERROR;     { not enough memory }
          exit;
        end;

        q := @hp[hn];
        u[h] := q;
        Inc(hn, z);

        { connect to last table, if there is one }
        if (h <> 0) then
        begin
          x[h] := i;             { save pattern for backing up }
          r.bits := Byte(l);     { bits to dump before this table }
          r.exop := Byte(j);     { bits in this table }
          j := i shr (w - l);
          {r.base := uInt( q - u[h-1] -j);}   { offset to this table }
          r.base := (ptr2int(q) - ptr2int(u[h-1]) ) div sizeof(q^) - j;
          huft_Ptr(u[h-1])^[j] := r;  { connect to last table }
        end
        else
          t^ := q;               { first table is returned result }
      end;

      { set up table entry in r }
      r.bits := Byte(k - w);

      { C-code: if (p >= v + n) - see ZUTIL.PAS for comments }

      if ptr2int(p)>=ptr2int(@(v[n])) then  { also works under DPMI ?? }
        r.exop := 128 + 64                  { out of values--invalid code }
      else
        if (p^ < s) then
        begin
          if (p^ < 256) then     { 256 is end-of-block code }
            r.exop := 0
          Else
            r.exop := 32 + 64;   { EOB_code; }
          r.base := p^;          { simple code is just the value }
          Inc(p);
        end
        Else
        begin
          r.exop := Byte(e[p^-s] + 16 + 64);  { non-simple--look up in lists }
          r.base := d[p^-s];
          Inc (p);
        end ;

      { fill code-like entries with r }
      f := 1 shl (k - w);
      j := i shr w;
      while (j < z) do
      begin
        huft_Ptr(q)^[j] := r;
        Inc(j, f);
      end;

      { backwards increment the k-bit code i }
      j := 1 shl (k-1) ;
      while (i and j) <> 0 do
      begin
        i := i xor j;         { bitwise exclusive or }
        j := j shr 1
      end ;
      i := i xor j;

      { backup over finished tables }
      mask := (1 shl w) - 1;   { needed on HP, cc -O bug }
      while ((i and mask) <> x[h]) do
      begin
        Dec(h);                { don't need to update q }
        Dec(w, l);
        mask := (1 shl w) - 1;
      end;

    end;

    Inc(k);
  end;

  { Return Z_BUF_ERROR if we were given an incomplete table }
  if (y <> 0) And (g <> 1) then
    huft_build := Z_BUF_ERROR
  else
    huft_build := Z_OK;
end; { huft_build}


function inflate_trees_bits(
  var c : array of uIntf;  { 19 code lengths }
  var bb : uIntf;          { bits tree desired/actual depth }
  var tb : pinflate_huft;  { bits tree result }
  var hp : array of Inflate_huft;      { space for trees }
  var z : z_stream         { for messages }
    ) : TsgInteger;
var
  r : TsgInteger;
  hn : uInt;          { hufts used in space }
  v : PuIntArray;     { work area for huft_build }
begin
  hn := 0;
  v := PuIntArray( ZALLOC(z, 19, sizeof(uInt)) );
  if (v = Z_NULL) then
  begin
    inflate_trees_bits := Z_MEM_ERROR;
    exit;
  end;

  r := huft_build(c, 19, 19, cplens, cplext,
                             {puIntf(Z_NULL), puIntf(Z_NULL),}
                  @tb, bb, hp, hn, v^);
  if (r = Z_DATA_ERROR) then
    z.msg := 'oversubscribed dynamic bit lengths tree'
  else
    if (r = Z_BUF_ERROR) or (bb = 0) then
    begin
      z.msg := 'incomplete dynamic bit lengths tree';
      r := Z_DATA_ERROR;
    end;
  ZFREE(z, v);
  inflate_trees_bits := r;
end;


function inflate_trees_dynamic(
    nl : uInt;                    { number of literal/length codes }
    nd : uInt;                    { number of distance codes }
    var c : Array of uIntf;           { that many (total) code lengths }
    var bl : uIntf;          { literal desired/actual bit depth }
    var bd : uIntf;          { distance desired/actual bit depth }
var tl : pInflate_huft;           { literal/length tree result }
var td : pInflate_huft;           { distance tree result }
var hp : array of Inflate_huft;   { space for trees }
var z : z_stream                  { for messages }
     ) : TsgInteger;
var
  r : TsgInteger;
  hn : uInt;          { hufts used in space }
  v : PuIntArray;     { work area for huft_build }
begin
  hn := 0;
  { allocate work area }
  v := PuIntArray( ZALLOC(z, 288, sizeof(uInt)) );
  if (v = Z_NULL) then
  begin
    inflate_trees_dynamic := Z_MEM_ERROR;
    exit;
  end;

  { build literal/length tree }
  r := huft_build(c, nl, 257, cplens, cplext, @tl, bl, hp, hn, v^);
  if (r <> Z_OK) or (bl = 0) then
  begin
    if (r = Z_DATA_ERROR) then
      z.msg := 'oversubscribed literal/length tree'
    else
      if (r <> Z_MEM_ERROR) then
      begin
        z.msg := 'incomplete literal/length tree';
        r := Z_DATA_ERROR;
      end;

    ZFREE(z, v);
    inflate_trees_dynamic := r;
    exit;
  end;

  { build distance tree }
  r := huft_build(puIntArray(@c[nl])^, nd, 0,
                  cpdist, cpdext, @td, bd, hp, hn, v^);
  if (r <> Z_OK) or ((bd = 0) and (nl > 257)) then
  begin
    if (r = Z_DATA_ERROR) then
      z.msg := 'oversubscribed literal/length tree'
    else
      if (r = Z_BUF_ERROR) then
      begin
{$ifdef PKZIP_BUG_WORKAROUND}
        r := Z_OK;
      end;
{$else}
        z.msg := 'incomplete literal/length tree';
        r := Z_DATA_ERROR;
      end
      else
        if (r <> Z_MEM_ERROR) then
        begin
          z.msg := 'empty distance tree with lengths';
          r := Z_DATA_ERROR;
        end;
    ZFREE(z, v);
    inflate_trees_dynamic := r;
    exit;
{$endif}
  end;

  { done }
  ZFREE(z, v);
  inflate_trees_dynamic := Z_OK;
end;

{$UNDEF BUILDFIXED}

{ build fixed tables only once--keep them here }
{$IFNDEF BUILDFIXED}
{ locals }
const
  fixed_built : Boolean = false;
  FIXEDH = 544;      { number of hufts used by fixed tables }
var
  fixed_mem : array[0..FIXEDH-1] of inflate_huft;
  fixed_bl : uInt;
  fixed_bd : uInt;
  fixed_tl : pInflate_huft;
  fixed_td : pInflate_huft;

{$ELSE}

{ inffixed.h -- table for decoding fixed codes }

{local}
const
  fixed_bl = uInt(9);
{local}
const
  fixed_bd = uInt(5);
{local}
const
  fixed_tl : array [0..288-1] of inflate_huft = (
    Exop,             { number of extra bits or operation }
    bits : Byte;      { number of bits in this code or subcode }
    {pad : uInt;}       { pad structure to a power of 2 (4 bytes for }
                      {  16-bit, 8 bytes for 32-bit TsgInteger's) }
    base : uInt;      { literal, length base, or distance base }
                      { or table offset }

    ((96,7),256), ((0,8),80), ((0,8),16), ((84,8),115), ((82,7),31),
    ((0,8),112), ((0,8),48), ((0,9),192), ((80,7),10), ((0,8),96),
    ((0,8),32), ((0,9),160), ((0,8),0), ((0,8),128), ((0,8),64),
    ((0,9),224), ((80,7),6), ((0,8),88), ((0,8),24), ((0,9),144),
    ((83,7),59), ((0,8),120), ((0,8),56), ((0,9),208), ((81,7),17),
    ((0,8),104), ((0,8),40), ((0,9),176), ((0,8),8), ((0,8),136),
    ((0,8),72), ((0,9),240), ((80,7),4), ((0,8),84), ((0,8),20),
    ((85,8),227), ((83,7),43), ((0,8),116), ((0,8),52), ((0,9),200),
    ((81,7),13), ((0,8),100), ((0,8),36), ((0,9),168), ((0,8),4),
    ((0,8),132), ((0,8),68), ((0,9),232), ((80,7),8), ((0,8),92),
    ((0,8),28), ((0,9),152), ((84,7),83), ((0,8),124), ((0,8),60),
    ((0,9),216), ((82,7),23), ((0,8),108), ((0,8),44), ((0,9),184),
    ((0,8),12), ((0,8),140), ((0,8),76), ((0,9),248), ((80,7),3),
    ((0,8),82), ((0,8),18), ((85,8),163), ((83,7),35), ((0,8),114),
    ((0,8),50), ((0,9),196), ((81,7),11), ((0,8),98), ((0,8),34),
    ((0,9),164), ((0,8),2), ((0,8),130), ((0,8),66), ((0,9),228),
    ((80,7),7), ((0,8),90), ((0,8),26), ((0,9),148), ((84,7),67),
    ((0,8),122), ((0,8),58), ((0,9),212), ((82,7),19), ((0,8),106),
    ((0,8),42), ((0,9),180), ((0,8),10), ((0,8),138), ((0,8),74),
    ((0,9),244), ((80,7),5), ((0,8),86), ((0,8),22), ((192,8),0),
    ((83,7),51), ((0,8),118), ((0,8),54), ((0,9),204), ((81,7),15),
    ((0,8),102), ((0,8),38), ((0,9),172), ((0,8),6), ((0,8),134),
    ((0,8),70), ((0,9),236), ((80,7),9), ((0,8),94), ((0,8),30),
    ((0,9),156), ((84,7),99), ((0,8),126), ((0,8),62), ((0,9),220),
    ((82,7),27), ((0,8),110), ((0,8),46), ((0,9),188), ((0,8),14),
    ((0,8),142), ((0,8),78), ((0,9),252), ((96,7),256), ((0,8),81),
    ((0,8),17), ((85,8),131), ((82,7),31), ((0,8),113), ((0,8),49),
    ((0,9),194), ((80,7),10), ((0,8),97), ((0,8),33), ((0,9),162),
    ((0,8),1), ((0,8),129), ((0,8),65), ((0,9),226), ((80,7),6),
    ((0,8),89), ((0,8),25), ((0,9),146), ((83,7),59), ((0,8),121),
    ((0,8),57), ((0,9),210), ((81,7),17), ((0,8),105), ((0,8),41),
    ((0,9),178), ((0,8),9), ((0,8),137), ((0,8),73), ((0,9),242),
    ((80,7),4), ((0,8),85), ((0,8),21), ((80,8),258), ((83,7),43),
    ((0,8),117), ((0,8),53), ((0,9),202), ((81,7),13), ((0,8),101),
    ((0,8),37), ((0,9),170), ((0,8),5), ((0,8),133), ((0,8),69),
    ((0,9),234), ((80,7),8), ((0,8),93), ((0,8),29), ((0,9),154),
    ((84,7),83), ((0,8),125), ((0,8),61), ((0,9),218), ((82,7),23),
    ((0,8),109), ((0,8),45), ((0,9),186), ((0,8),13), ((0,8),141),
    ((0,8),77), ((0,9),250), ((80,7),3), ((0,8),83), ((0,8),19),
    ((85,8),195), ((83,7),35), ((0,8),115), ((0,8),51), ((0,9),198),
    ((81,7),11), ((0,8),99), ((0,8),35), ((0,9),166), ((0,8),3),
    ((0,8),131), ((0,8),67), ((0,9),230), ((80,7),7), ((0,8),91),
    ((0,8),27), ((0,9),150), ((84,7),67), ((0,8),123), ((0,8),59),
    ((0,9),214), ((82,7),19), ((0,8),107), ((0,8),43), ((0,9),182),
    ((0,8),11), ((0,8),139), ((0,8),75), ((0,9),246), ((80,7),5),
    ((0,8),87), ((0,8),23), ((192,8),0), ((83,7),51), ((0,8),119),
    ((0,8),55), ((0,9),206), ((81,7),15), ((0,8),103), ((0,8),39),
    ((0,9),174), ((0,8),7), ((0,8),135), ((0,8),71), ((0,9),238),
    ((80,7),9), ((0,8),95), ((0,8),31), ((0,9),158), ((84,7),99),
    ((0,8),127), ((0,8),63), ((0,9),222), ((82,7),27), ((0,8),111),
    ((0,8),47), ((0,9),190), ((0,8),15), ((0,8),143), ((0,8),79),
    ((0,9),254), ((96,7),256), ((0,8),80), ((0,8),16), ((84,8),115),
    ((82,7),31), ((0,8),112), ((0,8),48), ((0,9),193), ((80,7),10),
    ((0,8),96), ((0,8),32), ((0,9),161), ((0,8),0), ((0,8),128),
    ((0,8),64), ((0,9),225), ((80,7),6), ((0,8),88), ((0,8),24),
    ((0,9),145), ((83,7),59), ((0,8),120), ((0,8),56), ((0,9),209),
    ((81,7),17), ((0,8),104), ((0,8),40), ((0,9),177), ((0,8),8),
    ((0,8),136), ((0,8),72), ((0,9),241), ((80,7),4), ((0,8),84),
    ((0,8),20), ((85,8),227), ((83,7),43), ((0,8),116), ((0,8),52),
    ((0,9),201), ((81,7),13), ((0,8),100), ((0,8),36), ((0,9),169),
    ((0,8),4), ((0,8),132), ((0,8),68), ((0,9),233), ((80,7),8),
    ((0,8),92), ((0,8),28), ((0,9),153), ((84,7),83), ((0,8),124),
    ((0,8),60), ((0,9),217), ((82,7),23), ((0,8),108), ((0,8),44),
    ((0,9),185), ((0,8),12), ((0,8),140), ((0,8),76), ((0,9),249),
    ((80,7),3), ((0,8),82), ((0,8),18), ((85,8),163), ((83,7),35),
    ((0,8),114), ((0,8),50), ((0,9),197), ((81,7),11), ((0,8),98),
    ((0,8),34), ((0,9),165), ((0,8),2), ((0,8),130), ((0,8),66),
    ((0,9),229), ((80,7),7), ((0,8),90), ((0,8),26), ((0,9),149),
    ((84,7),67), ((0,8),122), ((0,8),58), ((0,9),213), ((82,7),19),
    ((0,8),106), ((0,8),42), ((0,9),181), ((0,8),10), ((0,8),138),
    ((0,8),74), ((0,9),245), ((80,7),5), ((0,8),86), ((0,8),22),
    ((192,8),0), ((83,7),51), ((0,8),118), ((0,8),54), ((0,9),205),
    ((81,7),15), ((0,8),102), ((0,8),38), ((0,9),173), ((0,8),6),
    ((0,8),134), ((0,8),70), ((0,9),237), ((80,7),9), ((0,8),94),
    ((0,8),30), ((0,9),157), ((84,7),99), ((0,8),126), ((0,8),62),
    ((0,9),221), ((82,7),27), ((0,8),110), ((0,8),46), ((0,9),189),
    ((0,8),14), ((0,8),142), ((0,8),78), ((0,9),253), ((96,7),256),
    ((0,8),81), ((0,8),17), ((85,8),131), ((82,7),31), ((0,8),113),
    ((0,8),49), ((0,9),195), ((80,7),10), ((0,8),97), ((0,8),33),
    ((0,9),163), ((0,8),1), ((0,8),129), ((0,8),65), ((0,9),227),
    ((80,7),6), ((0,8),89), ((0,8),25), ((0,9),147), ((83,7),59),
    ((0,8),121), ((0,8),57), ((0,9),211), ((81,7),17), ((0,8),105),
    ((0,8),41), ((0,9),179), ((0,8),9), ((0,8),137), ((0,8),73),
    ((0,9),243), ((80,7),4), ((0,8),85), ((0,8),21), ((80,8),258),
    ((83,7),43), ((0,8),117), ((0,8),53), ((0,9),203), ((81,7),13),
    ((0,8),101), ((0,8),37), ((0,9),171), ((0,8),5), ((0,8),133),
    ((0,8),69), ((0,9),235), ((80,7),8), ((0,8),93), ((0,8),29),
    ((0,9),155), ((84,7),83), ((0,8),125), ((0,8),61), ((0,9),219),
    ((82,7),23), ((0,8),109), ((0,8),45), ((0,9),187), ((0,8),13),
    ((0,8),141), ((0,8),77), ((0,9),251), ((80,7),3), ((0,8),83),
    ((0,8),19), ((85,8),195), ((83,7),35), ((0,8),115), ((0,8),51),
    ((0,9),199), ((81,7),11), ((0,8),99), ((0,8),35), ((0,9),167),
    ((0,8),3), ((0,8),131), ((0,8),67), ((0,9),231), ((80,7),7),
    ((0,8),91), ((0,8),27), ((0,9),151), ((84,7),67), ((0,8),123),
    ((0,8),59), ((0,9),215), ((82,7),19), ((0,8),107), ((0,8),43),
    ((0,9),183), ((0,8),11), ((0,8),139), ((0,8),75), ((0,9),247),
    ((80,7),5), ((0,8),87), ((0,8),23), ((192,8),0), ((83,7),51),
    ((0,8),119), ((0,8),55), ((0,9),207), ((81,7),15), ((0,8),103),
    ((0,8),39), ((0,9),175), ((0,8),7), ((0,8),135), ((0,8),71),
    ((0,9),239), ((80,7),9), ((0,8),95), ((0,8),31), ((0,9),159),
    ((84,7),99), ((0,8),127), ((0,8),63), ((0,9),223), ((82,7),27),
    ((0,8),111), ((0,8),47), ((0,9),191), ((0,8),15), ((0,8),143),
    ((0,8),79), ((0,9),255)
  );

{local}
const
  fixed_td : array[0..32-1] of inflate_huft = (
(Exop:80;bits:5;base:1),      (Exop:87;bits:5;base:257),   (Exop:83;bits:5;base:17),
(Exop:91;bits:5;base:4097),   (Exop:81;bits:5;base),       (Exop:89;bits:5;base:1025),
(Exop:85;bits:5;base:65),     (Exop:93;bits:5;base:16385), (Exop:80;bits:5;base:3),
(Exop:88;bits:5;base:513),    (Exop:84;bits:5;base:33),    (Exop:92;bits:5;base:8193),
(Exop:82;bits:5;base:9),      (Exop:90;bits:5;base:2049),  (Exop:86;bits:5;base:129),
(Exop:192;bits:5;base:24577), (Exop:80;bits:5;base:2),     (Exop:87;bits:5;base:385),
(Exop:83;bits:5;base:25),     (Exop:91;bits:5;base:6145),  (Exop:81;bits:5;base:7),
(Exop:89;bits:5;base:1537),   (Exop:85;bits:5;base:97),    (Exop:93;bits:5;base:24577),
(Exop:80;bits:5;base:4),      (Exop:88;bits:5;base:769),   (Exop:84;bits:5;base:49),
(Exop:92;bits:5;base:12289),  (Exop:82;bits:5;base:13),    (Exop:90;bits:5;base:3073),
(Exop:86;bits:5;base:193),    (Exop:192;bits:5;base:24577)
  );
{$ENDIF}

function inflate_trees_fixed(
var bl : uInt;               { literal desired/actual bit depth }
var bd : uInt;               { distance desired/actual bit depth }
var tl : pInflate_huft;      { literal/length tree result }
var td : pInflate_huft;      { distance tree result }
var  z : z_stream            { for memory allocation }
      ) : TsgInteger;
type
  pFixed_table = ^fixed_table;
  fixed_table = array[0..288-1] of uIntf;
var
  k : TsgInteger;                   { temporary variable }
  c : pFixed_table;          { length list for huft_build }
  v : PuIntArray;            { work area for huft_build }
var
  f : uInt;                  { number of hufts used in fixed_mem }
begin
  { build fixed tables if not already (multiple overlapped executions ok) }
  if not fixed_built then
  begin
    f := 0;

    { allocate memory }
    c := pFixed_table( ZALLOC(z, 288, sizeof(uInt)) );
    if (c = Z_NULL) then
    begin
      inflate_trees_fixed := Z_MEM_ERROR;
      exit;
    end;
    v := PuIntArray( ZALLOC(z, 288, sizeof(uInt)) );
    if (v = Z_NULL) then
    begin
      ZFREE(z, c);
      inflate_trees_fixed := Z_MEM_ERROR;
      exit;
    end;

    { literal table }
    for k := 0 to Pred(144) do
      c^[k] := 8;
    for k := 144 to Pred(256) do
      c^[k] := 9;
    for k := 256 to Pred(280) do
      c^[k] := 7;
    for k := 280 to Pred(288) do
      c^[k] := 8;
    fixed_bl := 9;
    huft_build(c^, 288, 257, cplens, cplext, @fixed_tl, fixed_bl,
               fixed_mem, f, v^);

    { distance table }
    for k := 0 to Pred(30) do
      c^[k] := 5;
    fixed_bd := 5;
    huft_build(c^, 30, 0, cpdist, cpdext, @fixed_td, fixed_bd,
               fixed_mem, f, v^);

    { done }
    ZFREE(z, v);
    ZFREE(z, c);
    fixed_built := True;
  end;
  bl := fixed_bl;
  bd := fixed_bd;
  tl := fixed_tl;
  td := fixed_td;
  inflate_trees_fixed := Z_OK;
end; { inflate_trees_fixed }

{ infblock.h and
  infblock.c -- interpret and process block types to last block
  Copyright (C) 1995-1998 Mark Adler

  infblock.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{ Tables for deflate from PKZIP's appnote.txt. }
Const
  border : Array [0..18] Of Word  { Order of the bit length code lengths }
    = (16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15);

procedure inflate_blocks_reset (var s : inflate_blocks_state;
                                var z : z_stream;
                                c : puLong); { check value on output }
begin
  if (c <> Z_NULL) then
    c^ := s.check;
  if (s.mode = BTREE) or (s.mode = DTREE) then
    ZFREE(z, s.sub.trees.blens);
  if (s.mode = CODES) then
    inflate_codes_free(s.sub.decode.codes, z);

  s.mode := ZTYPE;
  s.bitk := 0;
  s.bitb := 0;

  s.write := s.window;
  s.read := s.window;
  if Assigned(s.checkfn) then
  begin
    s.check := s.checkfn(uLong(0), pBytef(NIL), 0);
    z.adler := s.check;
  end;
  {$IFDEF DEBUG}
  Tracev('inflate:   blocks reset');
  {$ENDIF}
end;


function inflate_blocks_new(var z : z_stream;
                            c : check_func;  { check function }
                            w : uInt         { window size }
                            ) : pInflate_blocks_state;
var
  s : pInflate_blocks_state;
begin
  s := pInflate_blocks_state( ZALLOC(z,1, sizeof(inflate_blocks_state)) );
  if (s = Z_NULL) then
  begin
    inflate_blocks_new := s;
    exit;
  end;
  s^.hufts := huft_ptr( ZALLOC(z, sizeof(inflate_huft), MANY) );

  if (s^.hufts = Z_NULL) then
  begin
    ZFREE(z, s);
    inflate_blocks_new := Z_NULL;
    exit;
  end;

  s^.window := pBytef( ZALLOC(z, 1, w) );
  if (s^.window = Z_NULL) then
  begin
    ZFREE(z, s^.hufts);
    ZFREE(z, s);
    inflate_blocks_new := Z_NULL;
    exit;
  end;
  s^.zend := s^.window;
  Inc(s^.zend, w);
  s^.checkfn := c;
  s^.mode := ZTYPE;
  {$IFDEF DEBUG}
  Tracev('inflate:   blocks allocated');
  {$ENDIF}
  inflate_blocks_reset(s^, z, Z_NULL);
  inflate_blocks_new := s;
end;


function inflate_blocks (var s : inflate_blocks_state;
                         var z : z_stream;
                         r : TsgInteger) : TsgInteger;           { initial return code }
label
  start_btree, start_dtree,
  start_blkdone, start_dry,
  start_codes;

var
  t : uInt;               { temporary storage }
  b : uLong;              { bit buffer }
  k : uInt;               { bits in bit buffer }
  p : pBytef;             { input data pointer }
  n : uInt;               { bytes available there }
  q : pBytef;             { output window write pointer }
  m : uInt;               { bytes to end of window or read pointer }
{ fixed code blocks }
var
  bl, bd : uInt;
  tl, td : pInflate_huft;
var
  h : pInflate_huft;
  i, j, c : uInt;
var
  cs : pInflate_codes_state;
begin
  { copy input/output information to locals }
  p := z.next_in;
  n := z.avail_in;
  b := s.bitb;
  k := s.bitk;
  q := s.write;
  if ptr2int(q) < ptr2int(s.read) then
    m := uInt(ptr2int(s.read)-ptr2int(q)-1)
  else
    m := uInt(ptr2int(s.zend)-ptr2int(q));

{ decompress an inflated block }


  { process input based on current state }
  while True do
  Case s.mode of
    ZTYPE:
      begin
        {NEEDBITS(3);}
        while (k < 3) do
        begin
          {NEEDBYTE;}
          if (n <> 0) then
            r :=Z_OK
          else
          begin
            {UPDATE}
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_blocks := inflate_flush(s,z,r);
            exit;
          end;
          Dec(n);
          b := b or (uLong(p^) shl k);
          Inc(p);
          Inc(k, 8);
        end;

        t := uInt(b) and 7;
        s.last := boolean(t and 1);
        case (t shr 1) of
          0:                         { stored }
            begin
              {$IFDEF DEBUG}
              if s.last then
                Tracev('inflate:     stored block (last)')
              else
                Tracev('inflate:     stored block');
              {$ENDIF}
              {DUMPBITS(3);}
              b := b shr 3;
              Dec(k, 3);

              t := k and 7;                  { go to byte boundary }
              {DUMPBITS(t);}
              b := b shr t;
              Dec(k, t);

              s.mode := LENS;                { get length of stored block }
            end;
          1:                         { fixed }
            begin
              begin
                {$IFDEF DEBUG}
                if s.last then
                  Tracev('inflate:     fixed codes blocks (last)')
                else
                  Tracev('inflate:     fixed codes blocks');
                {$ENDIF}
                inflate_trees_fixed(bl, bd, tl, td, z);
                s.sub.decode.codes := inflate_codes_new(bl, bd, tl, td, z);
                if (s.sub.decode.codes = Z_NULL) then
                begin
                  r := Z_MEM_ERROR;
                  { update pointers and return }
                  s.bitb := b;
                  s.bitk := k;
                  z.avail_in := n;
                  Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
                  z.next_in := p;
                  s.write := q;
                  inflate_blocks := inflate_flush(s,z,r);
                  exit;
                end;
              end;
              {DUMPBITS(3);}
              b := b shr 3;
              Dec(k, 3);

              s.mode := CODES;
            end;
          2:                         { dynamic }
            begin
              {$IFDEF DEBUG}
              if s.last then
                Tracev('inflate:     dynamic codes block (last)')
              else
                Tracev('inflate:     dynamic codes block');
              {$ENDIF}
              {DUMPBITS(3);}
              b := b shr 3;
              Dec(k, 3);

              s.mode := TABLE;
            end;
          3:
            begin                   { illegal }
              {DUMPBITS(3);}
              b := b shr 3;
              Dec(k, 3);

              s.mode := BLKBAD;
              z.msg := 'invalid block type';
              r := Z_DATA_ERROR;
              { update pointers and return }
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_blocks := inflate_flush(s,z,r);
              exit;
            end;
        end;
      end;
    LENS:
      begin
        {NEEDBITS(32);}
        while (k < 32) do
        begin
          {NEEDBYTE;}
          if (n <> 0) then
            r :=Z_OK
          else
          begin
            {UPDATE}
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_blocks := inflate_flush(s,z,r);
            exit;
          end;
          Dec(n);
          b := b or (uLong(p^) shl k);
          Inc(p);
          Inc(k, 8);
        end;

        if (((not b) shr 16) and $ffff) <> (b and $ffff) then
        begin
          s.mode := BLKBAD;
          z.msg := 'invalid stored block lengths';
          r := Z_DATA_ERROR;
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
        s.sub.left := uInt(b) and $ffff;
        k := 0;
        b := 0;                      { dump bits }
        {$IFDEF DEBUG}
        Tracev('inflate:       stored length '+IntToStr(s.sub.left));
        {$ENDIF}
        if s.sub.left <> 0 then
          s.mode := STORED
        else
          if s.last then
            s.mode := DRY
          else
            s.mode := ZTYPE;
      end;
    STORED:
      begin
        if (n = 0) then
        begin
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
        {NEEDOUT}
        if (m = 0) then
        begin
          {WRAP}
          if (q = s.zend) and (s.read <> s.window) then
          begin
            q := s.window;
            if ptr2int(q) < ptr2int(s.read) then
              m := uInt(ptr2int(s.read)-ptr2int(q)-1)
            else
              m := uInt(ptr2int(s.zend)-ptr2int(q));
          end;

          if (m = 0) then
          begin
            {FLUSH}
            s.write := q;
            r := inflate_flush(s,z,r);
            q := s.write;
            if ptr2int(q) < ptr2int(s.read) then
              m := uInt(ptr2int(s.read)-ptr2int(q)-1)
            else
              m := uInt(ptr2int(s.zend)-ptr2int(q));

            {WRAP}
            if (q = s.zend) and (s.read <> s.window) then
            begin
              q := s.window;
              if ptr2int(q) < ptr2int(s.read) then
                m := uInt(ptr2int(s.read)-ptr2int(q)-1)
              else
                m := uInt(ptr2int(s.zend)-ptr2int(q));
            end;

            if (m = 0) then
            begin
              {UPDATE}
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_blocks := inflate_flush(s,z,r);
              exit;
            end;
          end;
        end;
        r := Z_OK;

        t := s.sub.left;
        if (t > n) then
          t := n;
        if (t > m) then
          t := m;
        zmemcpy(q, p, t);
        Inc(p, t);  Dec(n, t);
        Inc(q, t);  Dec(m, t);
        Dec(s.sub.left, t);
        if (s.sub.left = 0) then
        begin
          {$IFDEF DEBUG}
          if (ptr2int(q) >= ptr2int(s.read)) then
            Tracev('inflate:       stored end '+
                IntToStr(z.total_out + ptr2int(q) - ptr2int(s.read)) + ' total out')
          else
            Tracev('inflate:       stored end '+
                    IntToStr(z.total_out + ptr2int(s.zend) - ptr2int(s.read) +
                    ptr2int(q) - ptr2int(s.window)) +  ' total out');
          {$ENDIF}
          if s.last then
            s.mode := DRY
          else
            s.mode := ZTYPE;
        end;
      end;
    TABLE:
      begin
        {NEEDBITS(14);}
        while (k < 14) do
        begin
          {NEEDBYTE;}
          if (n <> 0) then
            r :=Z_OK
          else
          begin
            {UPDATE}
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_blocks := inflate_flush(s,z,r);
            exit;
          end;
          Dec(n);
          b := b or (uLong(p^) shl k);
          Inc(p);
          Inc(k, 8);
        end;

        t := uInt(b) and $3fff;
        s.sub.trees.table := t;
  {$ifndef PKZIP_BUG_WORKAROUND}
        if ((t and $1f) > 29) or (((t shr 5) and $1f) > 29) then
        begin
          s.mode := BLKBAD;
          z.msg := 'too many length or distance symbols';
          r := Z_DATA_ERROR;
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
  {$endif}
        t := 258 + (t and $1f) + ((t shr 5) and $1f);
        s.sub.trees.blens := puIntArray( ZALLOC(z, t, sizeof(uInt)) );
        if (s.sub.trees.blens = Z_NULL) then
        begin
          r := Z_MEM_ERROR;
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
        {DUMPBITS(14);}
        b := b shr 14;
        Dec(k, 14);

        s.sub.trees.index := 0;
        {$IFDEF DEBUG}
        Tracev('inflate:       table sizes ok');
        {$ENDIF}
        s.mode := BTREE;
        { fall trough case is handled by the while }
        { try GOTO for speed - Nomssi }
        goto start_btree;
      end;
    BTREE:
      begin
        start_btree:
        while (s.sub.trees.index < 4 + (s.sub.trees.table shr 10)) do
        begin
          {NEEDBITS(3);}
          while (k < 3) do
          begin
            {NEEDBYTE;}
            if (n <> 0) then
              r :=Z_OK
            else
            begin
              {UPDATE}
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_blocks := inflate_flush(s,z,r);
              exit;
            end;
            Dec(n);
            b := b or (uLong(p^) shl k);
            Inc(p);
            Inc(k, 8);
          end;

          s.sub.trees.blens^[border[s.sub.trees.index]] := uInt(b) and 7;
          Inc(s.sub.trees.index);
          {DUMPBITS(3);}
          b := b shr 3;
          Dec(k, 3);
        end;
        while (s.sub.trees.index < 19) do
        begin
          s.sub.trees.blens^[border[s.sub.trees.index]] := 0;
          Inc(s.sub.trees.index);
        end;
        s.sub.trees.bb := 7;
        t := inflate_trees_bits(s.sub.trees.blens^, s.sub.trees.bb,
                                s.sub.trees.tb, s.hufts^, z);
        if (t <> Z_OK) then
        begin
          ZFREE(z, s.sub.trees.blens);
          r := t;
          if (r = Z_DATA_ERROR) then
            s.mode := BLKBAD;
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
        s.sub.trees.index := 0;
        {$IFDEF DEBUG}
        Tracev('inflate:       bits tree ok');
        {$ENDIF}
        s.mode := DTREE;
        { fall through again }
        goto start_dtree;
      end;
    DTREE:
      begin
        start_dtree:
        while TRUE do
        begin
          t := s.sub.trees.table;
          if not (s.sub.trees.index < 258 +
                                     (t and $1f) + ((t shr 5) and $1f)) then
            break;
          t := s.sub.trees.bb;
          {NEEDBITS(t);}
          while (k < t) do
          begin
            {NEEDBYTE;}
            if (n <> 0) then
              r :=Z_OK
            else
            begin
              {UPDATE}
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_blocks := inflate_flush(s,z,r);
              exit;
            end;
            Dec(n);
            b := b or (uLong(p^) shl k);
            Inc(p);
            Inc(k, 8);
          end;

          h := s.sub.trees.tb;
          Inc(h, uInt(b) and inflate_mask[t]);
          t := h^.Bits;
          c := h^.Base;

          if (c < 16) then
          begin
            {DUMPBITS(t);}
            b := b shr t;
            Dec(k, t);

            s.sub.trees.blens^[s.sub.trees.index] := c;
            Inc(s.sub.trees.index);
          end
          else { c = 16..18 }
          begin
            if c = 18 then
            begin
              i := 7;
              j := 11;
            end
            else
            begin
              i := c - 14;
              j := 3;
            end;
            {NEEDBITS(t + i);}
            while (k < t + i) do
            begin
              {NEEDBYTE;}
              if (n <> 0) then
                r :=Z_OK
              else
              begin
                {UPDATE}
                s.bitb := b;
                s.bitk := k;
                z.avail_in := n;
                Inc(z.total_in, ptr2int(p)-ptr2int(z.next_in));
                z.next_in := p;
                s.write := q;
                inflate_blocks := inflate_flush(s,z,r);
                exit;
              end;
              Dec(n);
              b := b or (uLong(p^) shl k);
              Inc(p);
              Inc(k, 8);
            end;

            {DUMPBITS(t);}
            b := b shr t;
            Dec(k, t);

            Inc(j, uInt(b) and inflate_mask[i]);
            {DUMPBITS(i);}
            b := b shr i;
            Dec(k, i);

            i := s.sub.trees.index;
            t := s.sub.trees.table;
            if (i + j > 258 + (t and $1f) + ((t shr 5) and $1f)) or
               ((c = 16) and (i < 1)) then
            begin
              ZFREE(z, s.sub.trees.blens);
              s.mode := BLKBAD;
              z.msg := 'invalid bit length repeat';
              r := Z_DATA_ERROR;
              { update pointers and return }
              s.bitb := b;
              s.bitk := k;
              z.avail_in := n;
              Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
              z.next_in := p;
              s.write := q;
              inflate_blocks := inflate_flush(s,z,r);
              exit;
            end;
            if c = 16 then
              c := s.sub.trees.blens^[i - 1]
            else
              c := 0;
            repeat
              s.sub.trees.blens^[i] := c;
              Inc(i);
              Dec(j);
            until (j=0);
            s.sub.trees.index := i;
          end;
        end; { while }
        s.sub.trees.tb := Z_NULL;
        begin
          bl := 9;         { must be <= 9 for lookahead assumptions }
          bd := 6;         { must be <= 9 for lookahead assumptions }
          t := s.sub.trees.table;
          t := inflate_trees_dynamic(257 + (t and $1f),
                  1 + ((t shr 5) and $1f),
                  s.sub.trees.blens^, bl, bd, tl, td, s.hufts^, z);
          ZFREE(z, s.sub.trees.blens);
          if (t <> Z_OK) then
          begin
            if (t = uInt(Z_DATA_ERROR)) then
              s.mode := BLKBAD;
            r := t;
            { update pointers and return }
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_blocks := inflate_flush(s,z,r);
            exit;
          end;
          {$IFDEF DEBUG}
          Tracev('inflate:       trees ok');
          {$ENDIF}
          { c renamed to cs }
          cs := inflate_codes_new(bl, bd, tl, td, z);
          if (cs = Z_NULL) then
          begin
            r := Z_MEM_ERROR;
            { update pointers and return }
            s.bitb := b;
            s.bitk := k;
            z.avail_in := n;
            Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
            z.next_in := p;
            s.write := q;
            inflate_blocks := inflate_flush(s,z,r);
            exit;
          end;
          s.sub.decode.codes := cs;
        end;
        s.mode := CODES;
        { yet another falltrough }
        goto start_codes;
      end;
    CODES:
      begin
        start_codes:
        { update pointers }
        s.bitb := b;
        s.bitk := k;
        z.avail_in := n;
        Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
        z.next_in := p;
        s.write := q;

        r := inflate_codes(s, z, r);
        if (r <> Z_STREAM_END) then
        begin
          inflate_blocks := inflate_flush(s, z, r);
          exit;
        end;
        r := Z_OK;
        inflate_codes_free(s.sub.decode.codes, z);
        { load local pointers }
        p := z.next_in;
        n := z.avail_in;
        b := s.bitb;
        k := s.bitk;
        q := s.write;
        if ptr2int(q) < ptr2int(s.read) then
          m := uInt(ptr2int(s.read)-ptr2int(q)-1)
        else
          m := uInt(ptr2int(s.zend)-ptr2int(q));
        {$IFDEF DEBUG}
        if (ptr2int(q) >= ptr2int(s.read)) then
          Tracev('inflate:       codes end '+
              IntToStr(z.total_out + ptr2int(q) - ptr2int(s.read)) + ' total out')
        else
          Tracev('inflate:       codes end '+
                  IntToStr(z.total_out + ptr2int(s.zend) - ptr2int(s.read) +
                  ptr2int(q) - ptr2int(s.window)) +  ' total out');
        {$ENDIF}
        if (not s.last) then
        begin
          s.mode := ZTYPE;
          continue; { break for switch statement in C-code }
        end;
        {$ifndef patch112}
        if (k > 7) then           { return unused byte, if any }
        begin
          {$IFDEF DEBUG}
          Assert(k < 16, 'inflate_codes grabbed too many bytes');
          {$ENDIF}
          Dec(k, 8);
          Inc(n);
          Dec(p);                    { can always return one }
        end;
        {$endif}
        s.mode := DRY;
        { another falltrough }
        goto start_dry;
      end;
    DRY:
      begin
        start_dry:
        {FLUSH}
        s.write := q;
        r := inflate_flush(s,z,r);
        q := s.write;

        { not needed anymore, we are done:
        if ptr2int(q) < ptr2int(s.read) then
          m := uInt(ptr2int(s.read)-ptr2int(q)-1)
        else
          m := uInt(ptr2int(s.zend)-ptr2int(q));
        }

        if (s.read <> s.write) then
        begin
          { update pointers and return }
          s.bitb := b;
          s.bitk := k;
          z.avail_in := n;
          Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
          z.next_in := p;
          s.write := q;
          inflate_blocks := inflate_flush(s,z,r);
          exit;
        end;
        s.mode := BLKDONE;
        goto start_blkdone;
      end;
    BLKDONE:
      begin
        start_blkdone:
        r := Z_STREAM_END;
        { update pointers and return }
        s.bitb := b;
        s.bitk := k;
        z.avail_in := n;
        Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
        z.next_in := p;
        s.write := q;
        inflate_blocks := inflate_flush(s,z,r);
        exit;
      end;
    BLKBAD:
      begin
        r := Z_DATA_ERROR;
        { update pointers and return }
        s.bitb := b;
        s.bitk := k;
        z.avail_in := n;
        Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
        z.next_in := p;
        s.write := q;
        inflate_blocks := inflate_flush(s,z,r);
        exit;
      end;
    else
    begin
      r := Z_STREAM_ERROR;
      { update pointers and return }
      s.bitb := b;
      s.bitk := k;
      z.avail_in := n;
      Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
      z.next_in := p;
      s.write := q;
      inflate_blocks := inflate_flush(s,z,r);
      exit;
    end;
  end; { Case s.mode of }

end;


function inflate_blocks_free(s : pInflate_blocks_state;
                             var z : z_stream) : TsgInteger;
begin
  inflate_blocks_reset(s^, z, Z_NULL);
  ZFREE(z, s^.window);
  ZFREE(z, s^.hufts);
  ZFREE(z, s);
  {$IFDEF DEBUG}
  Trace('inflate:   blocks freed');
  {$ENDIF}
  inflate_blocks_free := Z_OK;
end;


procedure inflate_set_dictionary(var s : inflate_blocks_state;
                                 const d : array of byte; { dictionary }
                                 n : uInt);         { dictionary length }
begin
  zmemcpy(s.window, pBytef(@d), n);
  s.write := s.window;
  Inc(s.write, n);
  s.read := s.write;
end;


{ Returns true if inflate is currently at the end of a block generated
  by Z_SYNC_FLUSH or Z_FULL_FLUSH.
  IN assertion: s <> Z_NULL }

function inflate_blocks_sync_point(var s : inflate_blocks_state) : TsgInteger;
begin
  inflate_blocks_sync_point := TsgInteger(s.mode = LENS);
end;

{  inflate.c -- zlib interface to inflate modules
   Copyright (C) 1995-1998 Mark Adler

  zInflate.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

function inflateReset(var z : z_stream) : TsgInteger;
begin
  if (z.state = Z_NULL) then
  begin
    inflateReset :=  Z_STREAM_ERROR;
    exit;
  end;
  z.total_out := 0;
  z.total_in := 0;
  z.msg := '';
  if z.state^.nowrap then
    z.state^.mode := BLOCKS
  else
    z.state^.mode := METHOD;
  inflate_blocks_reset(z.state^.blocks^, z, Z_NULL);
  {$IFDEF DEBUG}
  Tracev('inflate: reset');
  {$ENDIF}
  inflateReset :=  Z_OK;
end;


function inflateEnd(var z : z_stream) : TsgInteger;
begin
  if (z.state = Z_NULL) or not Assigned(z.zfree) then
  begin
    inflateEnd :=  Z_STREAM_ERROR;
    exit;
  end;
  if (z.state^.blocks <> Z_NULL) then
    inflate_blocks_free(z.state^.blocks, z);
  ZFREE(z, z.state);
  z.state := Z_NULL;
  {$IFDEF DEBUG}
  Tracev('inflate: end');
  {$ENDIF}
  inflateEnd :=  Z_OK;
end;


function inflateInit2_(var z: z_stream;
                       w : TsgInteger;
                       const version : AnsiString;
                       stream_size : TsgInteger) : TsgInteger;
begin
  if (version = '') or (version[1] <> ZLIB_VERSION[1]) or
      (stream_size <> sizeof(z_stream)) then
  begin
    inflateInit2_ := Z_VERSION_ERROR;
    exit;
  end;
  { initialize state }
  { SetLength(strm.msg, 255); }
  z.msg := '';
  if not Assigned(z.zalloc) then
  begin
    {$IFDEF FPC}  z.zalloc := @zcalloc;  {$ELSE}
    z.zalloc := zcalloc;
    {$endif}
    z.opaque := voidpf(0);
  end;
  if not Assigned(z.zfree) then
    {$IFDEF FPC}  z.zfree := @zcfree;  {$ELSE}
    z.zfree := zcfree;
    {$ENDIF}

  z.state := pInternal_state( ZALLOC(z,1,sizeof(internal_state)) );
  if (z.state = Z_NULL) then
  begin
    inflateInit2_ := Z_MEM_ERROR;
    exit;
  end;

  z.state^.blocks := Z_NULL;

  { handle undocumented nowrap option (no zlib header or check) }
  z.state^.nowrap := FALSE;
  if (w < 0) then
  begin
    w := - w;
    z.state^.nowrap := TRUE;
  end;

  { set window size }
  if (w < 8) or (w > 15) then
  begin
    inflateEnd(z);
    inflateInit2_ := Z_STREAM_ERROR;
    exit;
  end;
  z.state^.wbits := uInt(w);

  { create inflate_blocks state }
  if z.state^.nowrap then
    z.state^.blocks := inflate_blocks_new(z, NIL, uInt(1) shl w)
  else
  {$IFDEF FPC}
    z.state^.blocks := inflate_blocks_new(z, @adler32, uInt(1) shl w);
  {$ELSE}
    z.state^.blocks := inflate_blocks_new(z, adler32, uInt(1) shl w);
  {$ENDIF}
  if (z.state^.blocks = Z_NULL) then
  begin
    inflateEnd(z);
    inflateInit2_ := Z_MEM_ERROR;
    exit;
  end;
  {$IFDEF DEBUG}
  Tracev('inflate: allocated');
  {$ENDIF}
  { reset state }
  inflateReset(z);
  inflateInit2_ :=  Z_OK;
end;

function inflateInit2(var z: z_stream; windowBits : TsgInteger) : TsgInteger;
begin
  inflateInit2 := inflateInit2_(z, windowBits, ZLIB_VERSION, sizeof(z_stream));
end;


function inflateInit(var z : z_stream) : TsgInteger;
{ inflateInit is a macro to allow checking the zlib version
  and the compiler's view of z_stream:  }
begin
  inflateInit := inflateInit2_(z, DEF_WBITS, ZLIB_VERSION, sizeof(z_stream));
end;

function inflateInit_(z : z_streamp;
                      const version : AnsiString;
                      stream_size : TsgInteger) : TsgInteger;
begin
  { initialize state }
  if (z = Z_NULL) then
    inflateInit_ := Z_STREAM_ERROR
  else
    inflateInit_ := inflateInit2_(z^, DEF_WBITS, version, stream_size);
end;

function inflate(var z : z_stream;
                 f : TsgInteger) : TsgInteger;
var
  r : TsgInteger;
  b : uInt;
begin
  if (z.state = Z_NULL) or (z.next_in = Z_NULL) then
  begin
    inflate := Z_STREAM_ERROR;
    exit;
  end;
  if f = Z_FINISH then
    f := Z_BUF_ERROR
  else
    f := Z_OK;
  r := Z_BUF_ERROR;
  while True do
  case (z.state^.mode) of
    BLOCKS:
      begin
        r := inflate_blocks(z.state^.blocks^, z, r);
        if (r = Z_DATA_ERROR) then
        begin
          z.state^.mode := BAD;
          z.state^.sub.marker := 0;       { can try inflateSync }
          continue;            { break C-switch }
        end;
        if (r = Z_OK) then
          r := f;
        if (r <> Z_STREAM_END) then
        begin
          inflate := r;
          exit;
        end;
        r := f;
        inflate_blocks_reset(z.state^.blocks^, z, @z.state^.sub.check.was);
        if (z.state^.nowrap) then
        begin
          z.state^.mode := DONE;
          continue;            { break C-switch }
        end;
        z.state^.mode := CHECK4;  { falltrough }
      end;
    CHECK4:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;

        {z.state^.sub.check.need := uLong(NEXTBYTE(z)) shl 24;}
        Dec(z.avail_in);
        Inc(z.total_in);
        z.state^.sub.check.need := uLong(z.next_in^) shl 24;
        Inc(z.next_in);

        z.state^.mode := CHECK3;   { falltrough }
      end;
    CHECK3:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;
        {Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 16);}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 16);
        Inc(z.next_in);

        z.state^.mode := CHECK2;   { falltrough }
      end;
    CHECK2:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;

        {Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 8);}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 8);
        Inc(z.next_in);

        z.state^.mode := CHECK1;   { falltrough }
      end;
    CHECK1:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;
        {Inc( z.state^.sub.check.need, uLong(NEXTBYTE(z)) );}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) );
        Inc(z.next_in);


        if (z.state^.sub.check.was <> z.state^.sub.check.need) then
        begin
          z.state^.mode := BAD;
          z.msg := 'incorrect data check';
          z.state^.sub.marker := 5;       { can't try inflateSync }
          continue;           { break C-switch }
        end;
        {$IFDEF DEBUG}
        Tracev('inflate: zlib check ok');
        {$ENDIF}
        z.state^.mode := DONE; { falltrough }
      end;
    DONE:
      begin
        inflate := Z_STREAM_END;
        exit;
      end;
    METHOD:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f; {}

        {z.state^.sub.method := NEXTBYTE(z);}
        Dec(z.avail_in);
        Inc(z.total_in);
        z.state^.sub.method := z.next_in^;
        Inc(z.next_in);

        if ((z.state^.sub.method and $0f) <> Z_DEFLATED) then
        begin
          z.state^.mode := BAD;
          z.msg := 'unknown compression method';
          z.state^.sub.marker := 5;       { can't try inflateSync }
          continue;  { break C-switch }
        end;
        if ((z.state^.sub.method shr 4) + 8 > z.state^.wbits) then
        begin
          z.state^.mode := BAD;
          z.msg := 'invalid window size';
          z.state^.sub.marker := 5;       { can't try inflateSync }
          continue; { break C-switch }
        end;
        z.state^.mode := FLAG;
        { fall trough }
      end;
    FLAG:
      begin
        {NEEDBYTE}
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f; {}
        {b := NEXTBYTE(z);}
        Dec(z.avail_in);
        Inc(z.total_in);
        b := z.next_in^;
        Inc(z.next_in);

        if (((z.state^.sub.method shl 8) + b) mod 31) <> 0 then {% mod ?}
        begin
          z.state^.mode := BAD;
          z.msg := 'incorrect header check';
          z.state^.sub.marker := 5;       { can't try inflateSync }
          continue;      { break C-switch }
        end;
        {$IFDEF DEBUG}
        Tracev('inflate: zlib header ok');
        {$ENDIF}
        if ((b and PRESET_DICT) = 0) then
        begin
          z.state^.mode := BLOCKS;
	  continue;      { break C-switch }
        end;
        z.state^.mode := DICT4;
        { falltrough }
      end;
    DICT4:
      begin
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;

        {z.state^.sub.check.need := uLong(NEXTBYTE(z)) shl 24;}
        Dec(z.avail_in);
        Inc(z.total_in);
        z.state^.sub.check.need :=  uLong(z.next_in^) shl 24;
        Inc(z.next_in);

        z.state^.mode := DICT3;        { falltrough }
      end;
    DICT3:
      begin
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;
        {Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 16);}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 16);
        Inc(z.next_in);

        z.state^.mode := DICT2;        { falltrough }
      end;
    DICT2:
      begin
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        r := f;

        {Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) shl 8);}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) shl 8);
        Inc(z.next_in);

        z.state^.mode := DICT1;        { falltrough }
      end;
    DICT1:
      begin
        if (z.avail_in = 0) then
        begin
          inflate := r;
          exit;
        end;
        { r := f;    ---  wird niemals benutzt }
        {Inc(z.state^.sub.check.need, uLong(NEXTBYTE(z)) );}
        Dec(z.avail_in);
        Inc(z.total_in);
        Inc(z.state^.sub.check.need, uLong(z.next_in^) );
        Inc(z.next_in);

        z.adler := z.state^.sub.check.need;
        z.state^.mode := DICT0;
        inflate := Z_NEED_DICT;
        exit;
      end;
    DICT0:
      begin
        z.state^.mode := BAD;
        z.msg := 'need dictionary';
        z.state^.sub.marker := 0;         { can try inflateSync }
        inflate := Z_STREAM_ERROR;
        exit;
      end;
    BAD:
      begin
        inflate := Z_DATA_ERROR;
        exit;
      end;
    else
      begin
        inflate := Z_STREAM_ERROR;
        exit;
      end;
  end;
{$ifdef NEED_DUMMY_result}
  result := Z_STREAM_ERROR;  { Some dumb compilers complain without this }
{$endif}
end;

function inflateSetDictionary(var z : z_stream;
                              dictionary : pBytef; {const array of byte}
                              dictLength : uInt) : TsgInteger;
var
  length : uInt;
begin
  length := dictLength;

  if (z.state = Z_NULL) or (z.state^.mode <> DICT0) then
  begin
    inflateSetDictionary := Z_STREAM_ERROR;
    exit;
  end;
  if (adler32(Long(1), dictionary, dictLength) <> z.adler) then
  begin
    inflateSetDictionary := Z_DATA_ERROR;
    exit;
  end;
  z.adler := Long(1);

  if (length >= (uInt(1) shl z.state^.wbits)) then
  begin
    length := (1 shl z.state^.wbits)-1;
    Inc( dictionary, dictLength - length);
  end;
  inflate_set_dictionary(z.state^.blocks^, dictionary^, length);
  z.state^.mode := BLOCKS;
  inflateSetDictionary := Z_OK;
end;


function inflateSync(var z : z_stream) : TsgInteger;
const
  mark : packed array[0..3] of byte = (0, 0, $ff, $ff);
var
  n : uInt;       { number of bytes to look at }
  p : pBytef;     { pointer to bytes }
  m : uInt;       { number of marker bytes found in a row }
  r, w : uLong;   { temporaries to save total_in and total_out }
begin
  { set up }
  if (z.state = Z_NULL) then
  begin
    inflateSync := Z_STREAM_ERROR;
    exit;
  end;
  if (z.state^.mode <> BAD) then
  begin
    z.state^.mode := BAD;
    z.state^.sub.marker := 0;
  end;
  n := z.avail_in;
  if (n = 0) then
  begin
    inflateSync := Z_BUF_ERROR;
    exit;
  end;
  p := z.next_in;
  m := z.state^.sub.marker;

  { search }
  while (n <> 0) and (m < 4) do
  begin
    if (p^ = mark[m]) then
      Inc(m)
    else
      if (p^ <> 0) then
        m := 0
      else
        m := 4 - m;
    Inc(p);
    Dec(n);
  end;

  { restore }
  Inc(z.total_in, ptr2int(p) - ptr2int(z.next_in));
  z.next_in := p;
  z.avail_in := n;
  z.state^.sub.marker := m;


  { return no joy or set up to restart on a new block }
  if (m <> 4) then
  begin
    inflateSync := Z_DATA_ERROR;
    exit;
  end;
  r := z.total_in;
  w := z.total_out;
  inflateReset(z);
  z.total_in := r;
  z.total_out := w;
  z.state^.mode := BLOCKS;
  inflateSync := Z_OK;
end;


{
  returns true if inflate is currently at the end of a block generated
  by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
  implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
  but removes the length bytes of the resulting empty stored block. When
  decompressing, PPP checks that at the end of input packet, inflate is
  waiting for these length bytes.
}

function inflateSyncPoint(var z : z_stream) : TsgInteger;
begin
  if (z.state = Z_NULL) or (z.state^.blocks = Z_NULL) then
  begin
    inflateSyncPoint := Z_STREAM_ERROR;
    exit;
  end;
  inflateSyncPoint := inflate_blocks_sync_point(z.state^.blocks^);
end;

{$T-}
{$define ORG_DEBUG}
{
  trees.c -- output deflated data using Huffman coding
  Copyright (C) 1995-1998 Jean-loup Gailly

  trees.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

{
 *  ALGORITHM
 *
 *      The "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in a compressed form which is itself
 * a Huffman encoding of the lengths of all the code strings (in
 * ascending order by source values).  The actual code strings are
 * reconstructed from the lengths in the inflate process, as described
 * in the deflate specification.
 *
 *  REFERENCES
 *
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 }

const
  LENGTH_CODES = 29;
{ number of length codes, not counting the special END_BLOCK code }

  LITERALS = 256;
{ number of literal bytes 0..255 }

  L_CODES = (LITERALS+1+LENGTH_CODES);
{ number of Literal or Length codes, including the END_BLOCK code }

  D_CODES = 30;
{ number of distance codes }

  BL_CODES = 19;
{ number of codes used to transfer the bit lengths }

  HEAP_SIZE = (2*L_CODES+1);
{ maximum heap size }

  MAX_BITS = 15;
{ All codes must not exceed MAX_BITS bits }

const
  INIT_STATE =  42;
  BUSY_STATE =  113;
  FINISH_STATE = 666;
{ Stream status }


{ Data structure describing a single value and its code AnsiString. }
type
  ct_data_ptr = ^ct_data;
  ct_data = record
    fc : record
      case byte of
      0:(freq : ush);       { frequency count }
      1:(code : ush);       { bit AnsiString }
    end;
    dl : record
      case byte of
      0:(dad : ush);        { father node in Huffman tree }
      1:(len : ush);        { length of bit AnsiString }
    end;
  end;

{ Freq = fc.freq
 Code = fc.code
 Dad = dl.dad
 Len = dl.len }

type
  ltree_type = array[0..HEAP_SIZE-1] of ct_data;    { literal and length tree }
  dtree_type = array[0..2*D_CODES+1-1] of ct_data;  { distance tree }
  htree_type = array[0..2*BL_CODES+1-1] of ct_data;  { Huffman tree for bit lengths }
  { generic tree type }
  tree_type = array[0..(MaxMemBlock div SizeOf(ct_data))-1] of ct_data;

  tree_ptr = ^tree_type;
  ltree_ptr = ^ltree_type;
  dtree_ptr = ^dtree_type;
  htree_ptr = ^htree_type;


type
  static_tree_desc_ptr = ^static_tree_desc;
  static_tree_desc =
         record
    {const} static_tree : tree_ptr;     { static tree or NIL }
    {const} extra_bits : pzIntfArray;   { extra bits for each code or NIL }
            extra_base : TsgInteger;           { base index for extra_bits }
            elems : TsgInteger;                { max number of elements in the tree }
            max_length : TsgInteger;           { max bit length for the codes }
          end;

  tree_desc_ptr = ^tree_desc;
  tree_desc = record
    dyn_tree : tree_ptr;    { the dynamic tree }
    max_code : TsgInteger;            { largest code with non zero frequency }
    stat_desc : static_tree_desc_ptr; { the corresponding static tree }
  end;

type
  Pos = ush;
  Posf = Pos; {FAR}
  IPos = uInt;

  pPosf = ^Posf;

  zPosfArray = array[0..(MaxMemBlock div SizeOf(Posf))-1] of Posf;
  pzPosfArray = ^zPosfArray;

{ A Pos is an index in the character window. We use short instead of TsgInteger to
  save space in the various tables. IPos is used only for parameter passing.}

type
  deflate_state_ptr = ^deflate_state;
  deflate_state = record
    strm : z_streamp;          { pointer back to this zlib stream }
    status : TsgInteger;              { as the name implies }
    pending_buf : pzByteArray; { output still pending }
    pending_buf_size : ulg;    { size of pending_buf }
    pending_out : pBytef;      { next pending byte to output to the stream }
    pending : TsgInteger;             { nb of bytes in the pending buffer }
    noheader : TsgInteger;            { suppress zlib header and adler32 }
    data_type : Byte;          { UNKNOWN, BINARY or ASCII }
    method : Byte;             { STORED (for zip only) or DEFLATED }
    last_flush : TsgInteger;          { value of flush param for previous deflate call }

                { used by deflate.pas: }

    w_size : uInt;             { LZ77 window size (32K by default) }
    w_bits : uInt;             { log2(w_size)  (8..16) }
    w_mask : uInt;             { w_size - 1 }

    window : pzByteArray;
    { Sliding window. Input bytes are read into the second half of the window,
      and move to the first half later to keep a dictionary of at least wSize
      bytes. With this organization, matches are limited to a distance of
      wSize-MAX_MATCH bytes, but this ensures that IO is always
      performed with a length multiple of the block size. Also, it limits
      the window size to 64K, which is quite useful on MSDOS.
      To do: use the user input buffer as sliding window. }

    window_size : ulg;
    { Actual size of window: 2*wSize, except when the user input buffer
      is directly used as sliding window. }

    prev : pzPosfArray;
    { Link to older AnsiString with same hash index. To limit the size of this
      array to 64K, this link is maintained only for the last 32K strings.
      An index in this array is thus a window index modulo 32K. }

    head : pzPosfArray;    { Heads of the hash chains or NIL. }

    ins_h : uInt;          { hash index of AnsiString to be inserted }
    hash_size : uInt;      { number of elements in hash table }
    hash_bits : uInt;      { log2(hash_size) }
    hash_mask : uInt;      { hash_size-1 }

    hash_shift : uInt;
    { Number of bits by which ins_h must be shifted at each input
      step. It must be such that after MIN_MATCH steps, the oldest
      byte no longer takes part in the hash key, that is:
        hash_shift * MIN_MATCH >= hash_bits     }

    block_start : long;
    { Window position at the beginning of the current output block. Gets
      negative when the window is moved backwards. }

    match_length : uInt;           { length of best match }
    prev_match : IPos;             { previous match }
    match_available : boolean;     { set if previous match exists }
    strstart : uInt;               { start of AnsiString to insert }
    match_start : uInt;            { start of matching AnsiString }
    lookahead : uInt;              { number of valid bytes ahead in window }

    prev_length : uInt;
    { Length of the best match at previous step. Matches not greater than this
      are discarded. This is used in the lazy match evaluation. }

    max_chain_length : uInt;
    { To speed up deflation, hash chains are never searched beyond this
      length.  A higher limit improves compression ratio but degrades the
      speed. }

    { moved to the end because Borland Pascal won't accept the following:
    max_lazy_match : uInt;
    max_insert_length : uInt absolute max_lazy_match;
    }

    level : TsgInteger;    { compression level (1..9) }
    strategy : TsgInteger; { favor or force Huffman coding}

    good_match : uInt;
    { Use a faster search when the previous match is longer than this }

    nice_match : TsgInteger; { Stop searching when current match exceeds this }

                { used by trees.pas: }
    { Didn't use ct_data typedef below to supress compiler warning }
    dyn_ltree : ltree_type;    { literal and length tree }
    dyn_dtree : dtree_type;  { distance tree }
    bl_tree : htree_type;   { Huffman tree for bit lengths }

    l_desc : tree_desc;                { desc. for literal tree }
    d_desc : tree_desc;                { desc. for distance tree }
    bl_desc : tree_desc;               { desc. for bit length tree }

    bl_count : array[0..MAX_BITS+1-1] of ush;
    { number of codes at each bit length for an optimal tree }

    heap : array[0..2*L_CODES+1-1] of TsgInteger; { heap used to build the Huffman trees }
    heap_len : TsgInteger;                   { number of elements in the heap }
    heap_max : TsgInteger;                   { element of largest frequency }
    { The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
      The same heap array is used to build all trees. }

    depth : array[0..2*L_CODES+1-1] of uch;
    { Depth of each subtree used as tie breaker for trees of equal frequency }


    l_buf : puchfArray;       { buffer for literals or lengths }

    lit_bufsize : uInt;
    { Size of match buffer for literals/lengths.  There are 4 reasons for
      limiting lit_bufsize to 64K:
        - frequencies can be kept in 16 bit counters
        - if compression is not successful for the first block, all input
          data is still in the window so we can still emit a stored block even
          when input comes from standard input.  (This can also be done for
          all blocks if lit_bufsize is not greater than 32K.)
        - if compression is not successful for a file smaller than 64K, we can
          even emit a stored file instead of a stored block (saving 5 bytes).
          This is applicable only for zip (not gzip or zlib).
        - creating new Huffman trees less frequently may not provide fast
          adaptation to changes in the input data statistics. (Take for
          example a binary file with poorly compressible code followed by
          a highly compressible AnsiString table.) Smaller buffer sizes give
          fast adaptation but have of course the overhead of transmitting
          trees more frequently.
        - I can't count above 4 }


    last_lit : uInt;      { running index in l_buf }

    d_buf : pushfArray;
    { Buffer for distances. To simplify the code, d_buf and l_buf have
      the same number of elements. To use different lengths, an extra flag
      array would be necessary. }

    opt_len : ulg;        { bit length of current block with optimal trees }
    static_len : ulg;     { bit length of current block with static trees }
    compressed_len : ulg; { total bit length of compressed file }
    matches : uInt;       { number of AnsiString matches in current block }
    last_eob_len : TsgInteger;   { bit length of EOB code for last block }

{$ifdef DEBUG}
    bits_sent : ulg;    { bit length of the compressed data }
{$endif}

    bi_buf : ush;
    { Output buffer. bits are inserted starting at the bottom (least
      significant bits). }

    bi_valid : TsgInteger;
    { Number of valid bits in bi_buf.  All bits above the last valid bit
      are always zero. }

    case byte of
    0:(max_lazy_match : uInt);
    { Attempt to find a better match only when the current match is strictly
      smaller than this value. This mechanism is used only for compression
      levels >= 4. }

    1:(max_insert_length : uInt);
    { Insert new strings in the hash table only if the match length is not
      greater than this length. This saves time but degrades compression.
      max_insert_length is used only for compression levels <= 3. }
  end;

{ #define GEN_TREES_H }

{$ifndef GEN_TREES_H}
{ header created automatically with -DGEN_TREES_H }

const
  DIST_CODE_LEN = 512; { see definition of array dist_code below }

{ The static literal tree. Since the bit lengths are imposed, there is no
  need for the L_CODES extra codes used during heap construction. However
  The codes 286 and 287 are needed to build a canonical tree (see _tr_init
  below). }
const
  static_ltree : array[0..L_CODES+2-1] of ct_data = (
{ fc:(freq, code) dl:(dad,len) }
(fc:(freq: 12);dl:(len: 8)), (fc:(freq:140);dl:(len: 8)), (fc:(freq: 76);dl:(len: 8)),
(fc:(freq:204);dl:(len: 8)), (fc:(freq: 44);dl:(len: 8)), (fc:(freq:172);dl:(len: 8)),
(fc:(freq:108);dl:(len: 8)), (fc:(freq:236);dl:(len: 8)), (fc:(freq: 28);dl:(len: 8)),
(fc:(freq:156);dl:(len: 8)), (fc:(freq: 92);dl:(len: 8)), (fc:(freq:220);dl:(len: 8)),
(fc:(freq: 60);dl:(len: 8)), (fc:(freq:188);dl:(len: 8)), (fc:(freq:124);dl:(len: 8)),
(fc:(freq:252);dl:(len: 8)), (fc:(freq:  2);dl:(len: 8)), (fc:(freq:130);dl:(len: 8)),
(fc:(freq: 66);dl:(len: 8)), (fc:(freq:194);dl:(len: 8)), (fc:(freq: 34);dl:(len: 8)),
(fc:(freq:162);dl:(len: 8)), (fc:(freq: 98);dl:(len: 8)), (fc:(freq:226);dl:(len: 8)),
(fc:(freq: 18);dl:(len: 8)), (fc:(freq:146);dl:(len: 8)), (fc:(freq: 82);dl:(len: 8)),
(fc:(freq:210);dl:(len: 8)), (fc:(freq: 50);dl:(len: 8)), (fc:(freq:178);dl:(len: 8)),
(fc:(freq:114);dl:(len: 8)), (fc:(freq:242);dl:(len: 8)), (fc:(freq: 10);dl:(len: 8)),
(fc:(freq:138);dl:(len: 8)), (fc:(freq: 74);dl:(len: 8)), (fc:(freq:202);dl:(len: 8)),
(fc:(freq: 42);dl:(len: 8)), (fc:(freq:170);dl:(len: 8)), (fc:(freq:106);dl:(len: 8)),
(fc:(freq:234);dl:(len: 8)), (fc:(freq: 26);dl:(len: 8)), (fc:(freq:154);dl:(len: 8)),
(fc:(freq: 90);dl:(len: 8)), (fc:(freq:218);dl:(len: 8)), (fc:(freq: 58);dl:(len: 8)),
(fc:(freq:186);dl:(len: 8)), (fc:(freq:122);dl:(len: 8)), (fc:(freq:250);dl:(len: 8)),
(fc:(freq:  6);dl:(len: 8)), (fc:(freq:134);dl:(len: 8)), (fc:(freq: 70);dl:(len: 8)),
(fc:(freq:198);dl:(len: 8)), (fc:(freq: 38);dl:(len: 8)), (fc:(freq:166);dl:(len: 8)),
(fc:(freq:102);dl:(len: 8)), (fc:(freq:230);dl:(len: 8)), (fc:(freq: 22);dl:(len: 8)),
(fc:(freq:150);dl:(len: 8)), (fc:(freq: 86);dl:(len: 8)), (fc:(freq:214);dl:(len: 8)),
(fc:(freq: 54);dl:(len: 8)), (fc:(freq:182);dl:(len: 8)), (fc:(freq:118);dl:(len: 8)),
(fc:(freq:246);dl:(len: 8)), (fc:(freq: 14);dl:(len: 8)), (fc:(freq:142);dl:(len: 8)),
(fc:(freq: 78);dl:(len: 8)), (fc:(freq:206);dl:(len: 8)), (fc:(freq: 46);dl:(len: 8)),
(fc:(freq:174);dl:(len: 8)), (fc:(freq:110);dl:(len: 8)), (fc:(freq:238);dl:(len: 8)),
(fc:(freq: 30);dl:(len: 8)), (fc:(freq:158);dl:(len: 8)), (fc:(freq: 94);dl:(len: 8)),
(fc:(freq:222);dl:(len: 8)), (fc:(freq: 62);dl:(len: 8)), (fc:(freq:190);dl:(len: 8)),
(fc:(freq:126);dl:(len: 8)), (fc:(freq:254);dl:(len: 8)), (fc:(freq:  1);dl:(len: 8)),
(fc:(freq:129);dl:(len: 8)), (fc:(freq: 65);dl:(len: 8)), (fc:(freq:193);dl:(len: 8)),
(fc:(freq: 33);dl:(len: 8)), (fc:(freq:161);dl:(len: 8)), (fc:(freq: 97);dl:(len: 8)),
(fc:(freq:225);dl:(len: 8)), (fc:(freq: 17);dl:(len: 8)), (fc:(freq:145);dl:(len: 8)),
(fc:(freq: 81);dl:(len: 8)), (fc:(freq:209);dl:(len: 8)), (fc:(freq: 49);dl:(len: 8)),
(fc:(freq:177);dl:(len: 8)), (fc:(freq:113);dl:(len: 8)), (fc:(freq:241);dl:(len: 8)),
(fc:(freq:  9);dl:(len: 8)), (fc:(freq:137);dl:(len: 8)), (fc:(freq: 73);dl:(len: 8)),
(fc:(freq:201);dl:(len: 8)), (fc:(freq: 41);dl:(len: 8)), (fc:(freq:169);dl:(len: 8)),
(fc:(freq:105);dl:(len: 8)), (fc:(freq:233);dl:(len: 8)), (fc:(freq: 25);dl:(len: 8)),
(fc:(freq:153);dl:(len: 8)), (fc:(freq: 89);dl:(len: 8)), (fc:(freq:217);dl:(len: 8)),
(fc:(freq: 57);dl:(len: 8)), (fc:(freq:185);dl:(len: 8)), (fc:(freq:121);dl:(len: 8)),
(fc:(freq:249);dl:(len: 8)), (fc:(freq:  5);dl:(len: 8)), (fc:(freq:133);dl:(len: 8)),
(fc:(freq: 69);dl:(len: 8)), (fc:(freq:197);dl:(len: 8)), (fc:(freq: 37);dl:(len: 8)),
(fc:(freq:165);dl:(len: 8)), (fc:(freq:101);dl:(len: 8)), (fc:(freq:229);dl:(len: 8)),
(fc:(freq: 21);dl:(len: 8)), (fc:(freq:149);dl:(len: 8)), (fc:(freq: 85);dl:(len: 8)),
(fc:(freq:213);dl:(len: 8)), (fc:(freq: 53);dl:(len: 8)), (fc:(freq:181);dl:(len: 8)),
(fc:(freq:117);dl:(len: 8)), (fc:(freq:245);dl:(len: 8)), (fc:(freq: 13);dl:(len: 8)),
(fc:(freq:141);dl:(len: 8)), (fc:(freq: 77);dl:(len: 8)), (fc:(freq:205);dl:(len: 8)),
(fc:(freq: 45);dl:(len: 8)), (fc:(freq:173);dl:(len: 8)), (fc:(freq:109);dl:(len: 8)),
(fc:(freq:237);dl:(len: 8)), (fc:(freq: 29);dl:(len: 8)), (fc:(freq:157);dl:(len: 8)),
(fc:(freq: 93);dl:(len: 8)), (fc:(freq:221);dl:(len: 8)), (fc:(freq: 61);dl:(len: 8)),
(fc:(freq:189);dl:(len: 8)), (fc:(freq:125);dl:(len: 8)), (fc:(freq:253);dl:(len: 8)),
(fc:(freq: 19);dl:(len: 9)), (fc:(freq:275);dl:(len: 9)), (fc:(freq:147);dl:(len: 9)),
(fc:(freq:403);dl:(len: 9)), (fc:(freq: 83);dl:(len: 9)), (fc:(freq:339);dl:(len: 9)),
(fc:(freq:211);dl:(len: 9)), (fc:(freq:467);dl:(len: 9)), (fc:(freq: 51);dl:(len: 9)),
(fc:(freq:307);dl:(len: 9)), (fc:(freq:179);dl:(len: 9)), (fc:(freq:435);dl:(len: 9)),
(fc:(freq:115);dl:(len: 9)), (fc:(freq:371);dl:(len: 9)), (fc:(freq:243);dl:(len: 9)),
(fc:(freq:499);dl:(len: 9)), (fc:(freq: 11);dl:(len: 9)), (fc:(freq:267);dl:(len: 9)),
(fc:(freq:139);dl:(len: 9)), (fc:(freq:395);dl:(len: 9)), (fc:(freq: 75);dl:(len: 9)),
(fc:(freq:331);dl:(len: 9)), (fc:(freq:203);dl:(len: 9)), (fc:(freq:459);dl:(len: 9)),
(fc:(freq: 43);dl:(len: 9)), (fc:(freq:299);dl:(len: 9)), (fc:(freq:171);dl:(len: 9)),
(fc:(freq:427);dl:(len: 9)), (fc:(freq:107);dl:(len: 9)), (fc:(freq:363);dl:(len: 9)),
(fc:(freq:235);dl:(len: 9)), (fc:(freq:491);dl:(len: 9)), (fc:(freq: 27);dl:(len: 9)),
(fc:(freq:283);dl:(len: 9)), (fc:(freq:155);dl:(len: 9)), (fc:(freq:411);dl:(len: 9)),
(fc:(freq: 91);dl:(len: 9)), (fc:(freq:347);dl:(len: 9)), (fc:(freq:219);dl:(len: 9)),
(fc:(freq:475);dl:(len: 9)), (fc:(freq: 59);dl:(len: 9)), (fc:(freq:315);dl:(len: 9)),
(fc:(freq:187);dl:(len: 9)), (fc:(freq:443);dl:(len: 9)), (fc:(freq:123);dl:(len: 9)),
(fc:(freq:379);dl:(len: 9)), (fc:(freq:251);dl:(len: 9)), (fc:(freq:507);dl:(len: 9)),
(fc:(freq:  7);dl:(len: 9)), (fc:(freq:263);dl:(len: 9)), (fc:(freq:135);dl:(len: 9)),
(fc:(freq:391);dl:(len: 9)), (fc:(freq: 71);dl:(len: 9)), (fc:(freq:327);dl:(len: 9)),
(fc:(freq:199);dl:(len: 9)), (fc:(freq:455);dl:(len: 9)), (fc:(freq: 39);dl:(len: 9)),
(fc:(freq:295);dl:(len: 9)), (fc:(freq:167);dl:(len: 9)), (fc:(freq:423);dl:(len: 9)),
(fc:(freq:103);dl:(len: 9)), (fc:(freq:359);dl:(len: 9)), (fc:(freq:231);dl:(len: 9)),
(fc:(freq:487);dl:(len: 9)), (fc:(freq: 23);dl:(len: 9)), (fc:(freq:279);dl:(len: 9)),
(fc:(freq:151);dl:(len: 9)), (fc:(freq:407);dl:(len: 9)), (fc:(freq: 87);dl:(len: 9)),
(fc:(freq:343);dl:(len: 9)), (fc:(freq:215);dl:(len: 9)), (fc:(freq:471);dl:(len: 9)),
(fc:(freq: 55);dl:(len: 9)), (fc:(freq:311);dl:(len: 9)), (fc:(freq:183);dl:(len: 9)),
(fc:(freq:439);dl:(len: 9)), (fc:(freq:119);dl:(len: 9)), (fc:(freq:375);dl:(len: 9)),
(fc:(freq:247);dl:(len: 9)), (fc:(freq:503);dl:(len: 9)), (fc:(freq: 15);dl:(len: 9)),
(fc:(freq:271);dl:(len: 9)), (fc:(freq:143);dl:(len: 9)), (fc:(freq:399);dl:(len: 9)),
(fc:(freq: 79);dl:(len: 9)), (fc:(freq:335);dl:(len: 9)), (fc:(freq:207);dl:(len: 9)),
(fc:(freq:463);dl:(len: 9)), (fc:(freq: 47);dl:(len: 9)), (fc:(freq:303);dl:(len: 9)),
(fc:(freq:175);dl:(len: 9)), (fc:(freq:431);dl:(len: 9)), (fc:(freq:111);dl:(len: 9)),
(fc:(freq:367);dl:(len: 9)), (fc:(freq:239);dl:(len: 9)), (fc:(freq:495);dl:(len: 9)),
(fc:(freq: 31);dl:(len: 9)), (fc:(freq:287);dl:(len: 9)), (fc:(freq:159);dl:(len: 9)),
(fc:(freq:415);dl:(len: 9)), (fc:(freq: 95);dl:(len: 9)), (fc:(freq:351);dl:(len: 9)),
(fc:(freq:223);dl:(len: 9)), (fc:(freq:479);dl:(len: 9)), (fc:(freq: 63);dl:(len: 9)),
(fc:(freq:319);dl:(len: 9)), (fc:(freq:191);dl:(len: 9)), (fc:(freq:447);dl:(len: 9)),
(fc:(freq:127);dl:(len: 9)), (fc:(freq:383);dl:(len: 9)), (fc:(freq:255);dl:(len: 9)),
(fc:(freq:511);dl:(len: 9)), (fc:(freq:  0);dl:(len: 7)), (fc:(freq: 64);dl:(len: 7)),
(fc:(freq: 32);dl:(len: 7)), (fc:(freq: 96);dl:(len: 7)), (fc:(freq: 16);dl:(len: 7)),
(fc:(freq: 80);dl:(len: 7)), (fc:(freq: 48);dl:(len: 7)), (fc:(freq:112);dl:(len: 7)),
(fc:(freq:  8);dl:(len: 7)), (fc:(freq: 72);dl:(len: 7)), (fc:(freq: 40);dl:(len: 7)),
(fc:(freq:104);dl:(len: 7)), (fc:(freq: 24);dl:(len: 7)), (fc:(freq: 88);dl:(len: 7)),
(fc:(freq: 56);dl:(len: 7)), (fc:(freq:120);dl:(len: 7)), (fc:(freq:  4);dl:(len: 7)),
(fc:(freq: 68);dl:(len: 7)), (fc:(freq: 36);dl:(len: 7)), (fc:(freq:100);dl:(len: 7)),
(fc:(freq: 20);dl:(len: 7)), (fc:(freq: 84);dl:(len: 7)), (fc:(freq: 52);dl:(len: 7)),
(fc:(freq:116);dl:(len: 7)), (fc:(freq:  3);dl:(len: 8)), (fc:(freq:131);dl:(len: 8)),
(fc:(freq: 67);dl:(len: 8)), (fc:(freq:195);dl:(len: 8)), (fc:(freq: 35);dl:(len: 8)),
(fc:(freq:163);dl:(len: 8)), (fc:(freq: 99);dl:(len: 8)), (fc:(freq:227);dl:(len: 8))
);


{ The static distance tree. (Actually a trivial tree since all lens use
  5 bits.) }
  static_dtree : array[0..D_CODES-1] of ct_data = (
(fc:(freq: 0); dl:(len:5)), (fc:(freq:16); dl:(len:5)), (fc:(freq: 8); dl:(len:5)),
(fc:(freq:24); dl:(len:5)), (fc:(freq: 4); dl:(len:5)), (fc:(freq:20); dl:(len:5)),
(fc:(freq:12); dl:(len:5)), (fc:(freq:28); dl:(len:5)), (fc:(freq: 2); dl:(len:5)),
(fc:(freq:18); dl:(len:5)), (fc:(freq:10); dl:(len:5)), (fc:(freq:26); dl:(len:5)),
(fc:(freq: 6); dl:(len:5)), (fc:(freq:22); dl:(len:5)), (fc:(freq:14); dl:(len:5)),
(fc:(freq:30); dl:(len:5)), (fc:(freq: 1); dl:(len:5)), (fc:(freq:17); dl:(len:5)),
(fc:(freq: 9); dl:(len:5)), (fc:(freq:25); dl:(len:5)), (fc:(freq: 5); dl:(len:5)),
(fc:(freq:21); dl:(len:5)), (fc:(freq:13); dl:(len:5)), (fc:(freq:29); dl:(len:5)),
(fc:(freq: 3); dl:(len:5)), (fc:(freq:19); dl:(len:5)), (fc:(freq:11); dl:(len:5)),
(fc:(freq:27); dl:(len:5)), (fc:(freq: 7); dl:(len:5)), (fc:(freq:23); dl:(len:5))
);

{ Distance codes. The first 256 values correspond to the distances
  3 .. 258, the last 256 values correspond to the top 8 bits of
  the 15 bit distances. }
  _dist_code : array[0..DIST_CODE_LEN-1] of uch = (
 0,  1,  2,  3,  4,  4,  5,  5,  6,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  8,
 8,  8,  8,  8,  9,  9,  9,  9,  9,  9,  9,  9, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,  0,  0, 16, 17,
18, 18, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29
);

{ length code for each normalized match length (0 == MIN_MATCH) }
  _length_code : array[0..MAX_MATCH-MIN_MATCH+1-1] of uch = (
 0,  1,  2,  3,  4,  5,  6,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 12, 12,
13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 28
);


{ First normalized length for each code (0 = MIN_MATCH) }
  base_length : array[0..LENGTH_CODES-1] of TsgInteger = (
0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
64, 80, 96, 112, 128, 160, 192, 224, 0
);


{ First normalized distance for each code (0 = distance of 1) }
  base_dist : array[0..D_CODES-1] of TsgInteger = (
    0,     1,     2,     3,     4,     6,     8,    12,    16,    24,
   32,    48,    64,    96,   128,   192,   256,   384,   512,   768,
 1024,  1536,  2048,  3072,  4096,  6144,  8192, 12288, 16384, 24576
);
{$endif}

{ Output a byte on the stream.
  IN assertion: there is enough room in pending_buf.
macro put_byte(s, c)
begin
  s^.pending_buf^[s^.pending] := (c);
  Inc(s^.pending);
end
}

{ Minimum amount of lookahead, except at the end of the input file.
  See deflate.c for comments about the MIN_MATCH+1. }

{macro d_code(dist)
   if (dist) < 256 then
     := _dist_code[dist]
   else
     := _dist_code[256+((dist) shr 7)]);
  Mapping from a distance to a distance code. dist is the distance - 1 and
  must not have side effects. _dist_code[256] and _dist_code[257] are never
  used. }

{$ifndef ORG_DEBUG}
{ Inline versions of _tr_tally for speed: }

#if defined(GEN_TREES_H) || !defined(STDC)
  extern uch _length_code[];
  extern uch _dist_code[];
#else
  extern const uch _length_code[];
  extern const uch _dist_code[];
#endif

macro _tr_tally_lit(s, c, flush)
var
  cc : uch;
begin
    cc := (c);
    s^.d_buf[s^.last_lit] := 0;
    s^.l_buf[s^.last_lit] := cc;
    Inc(s^.last_lit);
    Inc(s^.dyn_ltree[cc].fc.Freq);
    flush := (s^.last_lit = s^.lit_bufsize-1);
end;

macro _tr_tally_dist(s, distance, length, flush) \
var
  len : uch;
  dist : ush;
begin
    len := (length);
    dist := (distance);
    s^.d_buf[s^.last_lit] := dist;
    s^.l_buf[s^.last_lit] = len;
    Inc(s^.last_lit);
    Dec(dist);
    Inc(s^.dyn_ltree[_length_code[len]+LITERALS+1].fc.Freq);
    Inc(s^.dyn_dtree[d_code(dist)].Freq);
    flush := (s^.last_lit = s^.lit_bufsize-1);
end;

{$endif}

{ ===========================================================================
  Constants }

const
  MAX_BL_BITS = 7;
{ Bit length codes must not exceed MAX_BL_BITS bits }

const
  END_BLOCK = 256;
{ end of block literal code }

const
  REP_3_6 = 16;
{ repeat previous bit length 3-6 times (2 bits of repeat count) }

const
  REPZ_3_10 = 17;
{ repeat a zero length 3-10 times  (3 bits of repeat count) }

const
  REPZ_11_138 = 18;
{ repeat a zero length 11-138 times  (7 bits of repeat count) }

{local}
const
  extra_lbits : array[0..LENGTH_CODES-1] of TsgInteger
    { extra bits for each length code }
   = (0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0);

{local}
const
  extra_dbits : array[0..D_CODES-1] of TsgInteger
    { extra bits for each distance code }
   = (0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13);

{local}
const
  extra_blbits : array[0..BL_CODES-1] of TsgInteger { extra bits for each bit length code }
   = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7);

{local}
const
  bl_order : array[0..BL_CODES-1] of uch
   = (16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15);
{ The lengths of the bit length codes are sent in order of decreasing
  probability, to avoid transmitting the lengths for unused bit length codes.
 }

const
  Buf_size = (8 * 2*sizeof(AnsiChar));
{ Number of bits used within bi_buf. (bi_buf might be implemented on
  more than 16 bits on some systems.) }

{ ===========================================================================
  Local data. These are initialized only once. }


{$ifdef GEN_TREES_H)}
{ non ANSI compilers may not accept trees.h }

const
  DIST_CODE_LEN = 512; { see definition of array dist_code below }

{local}
var
  static_ltree : array[0..L_CODES+2-1] of ct_data;
{ The static literal tree. Since the bit lengths are imposed, there is no
  need for the L_CODES extra codes used during heap construction. However
  The codes 286 and 287 are needed to build a canonical tree (see _tr_init
  below). }

{local}
  static_dtree : array[0..D_CODES-1] of ct_data;
{ The static distance tree. (Actually a trivial tree since all codes use
  5 bits.) }

  _dist_code : array[0..DIST_CODE_LEN-1] of uch;
{ Distance codes. The first 256 values correspond to the distances
  3 .. 258, the last 256 values correspond to the top 8 bits of
  the 15 bit distances. }

  _length_code : array[0..MAX_MATCH-MIN_MATCH+1-1] of uch;
{ length code for each normalized match length (0 == MIN_MATCH) }

{local}
  base_length : array[0..LENGTH_CODES-1] of TsgInteger;
{ First normalized length for each code (0 = MIN_MATCH) }

{local}
  base_dist : array[0..D_CODES-1] of TsgInteger;
{ First normalized distance for each code (0 = distance of 1) }

{$endif} { GEN_TREES_H }

{local}
const
  static_l_desc :  static_tree_desc  =
      (static_tree: {tree_ptr}(@(static_ltree));  { pointer to array of ct_data }
       extra_bits: {pzIntfArray}(@(extra_lbits)); { pointer to array of TsgInteger }
       extra_base: LITERALS+1;
       elems: L_CODES;
       max_length: MAX_BITS);

{local}
const
  static_d_desc : static_tree_desc  =
      (static_tree: {tree_ptr}(@(static_dtree));
       extra_bits: {pzIntfArray}(@(extra_dbits));
       extra_base : 0;
       elems: D_CODES;
       max_length: MAX_BITS);

{local}
const
  static_bl_desc : static_tree_desc =
      (static_tree: {tree_ptr}(NIL);
       extra_bits: {pzIntfArray}@(extra_blbits);
       extra_base : 0;
       elems: BL_CODES;
       max_length: MAX_BL_BITS);

(* ===========================================================================
  Local (static) routines in this file. }

procedure tr_static_init;
procedure init_block(var deflate_state);
procedure pqdownheap(var s : deflate_state;
                     var tree : ct_data;
                     k : TsgInteger);
procedure gen_bitlen(var s : deflate_state;
                     var desc : tree_desc);
procedure gen_codes(var tree : ct_data;
                    max_code : TsgInteger;
                    bl_count : pushf);
procedure build_tree(var s : deflate_state;
                     var desc : tree_desc);
procedure scan_tree(var s : deflate_state;
                    var tree : ct_data;
                    max_code : TsgInteger);
procedure send_tree(var s : deflate_state;
                    var tree : ct_data;
                    max_code : TsgInteger);
function build_bl_tree(var deflate_state) : TsgInteger;
procedure send_all_trees(var deflate_state;
                         lcodes : TsgInteger;
                         dcodes : TsgInteger;
                         blcodes : TsgInteger);
procedure compress_block(var s : deflate_state;
                         var ltree : ct_data;
                         var dtree : ct_data);
procedure set_data_type(var s : deflate_state);
function bi_reverse(value : TsgUnsignedInt;
                    length : TsgInteger) : TsgUnsignedInt;
procedure bi_windup(var deflate_state);
procedure bi_flush(var deflate_state);
procedure copy_block(var deflate_state;
                     buf : pcharf;
                     len : TsgUnsignedInt;
                     header : TsgInteger);
*)

{$ifdef GEN_TREES_H}
{local}
procedure gen_trees_header;
{$endif}

(*
{ ===========================================================================
  Output a short LSB first on the stream.
  IN assertion: there is enough room in pendingBuf. }

macro put_short(s, w)
begin
    {put_byte(s, (uch)((w) & 0xff));}
    s.pending_buf^[s.pending] := uch((w) and $ff);
    Inc(s.pending);

    {put_byte(s, (uch)((ush)(w) >> 8));}
    s.pending_buf^[s.pending] := uch(ush(w) shr 8);;
    Inc(s.pending);
end
*)

{ ===========================================================================
  Send a value on a given number of bits.
  IN assertion: length <= 16 and value fits in length bits. }

{$ifdef ORG_DEBUG}

{local}
procedure send_bits(var s : deflate_state;
                    value : TsgInteger;   { value to send }
                    length : TsgInteger); { number of bits }
begin
  {$ifdef DEBUG}
  Tracevv(' l '+IntToStr(length)+ ' v '+IntToStr(value));
  Assert((length > 0) and (length <= 15), 'invalid length');
  Inc(s.bits_sent, ulg(length));
  {$ENDIF}

  { If not enough room in bi_buf, use (valid) bits from bi_buf and
    (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
    unused bits in value. }
  {$IFOPT Q+} {$Q-} {$DEFINE NoOverflowCheck} {$ENDIF}
  {$IFOPT R+} {$R-} {$DEFINE NoRangeCheck} {$ENDIF}
  if (s.bi_valid > TsgInteger(Buf_size) - length) then
  begin
    s.bi_buf := s.bi_buf or TsgInteger(value shl s.bi_valid);
    {put_short(s, s.bi_buf);}
    s.pending_buf^[s.pending] := uch(s.bi_buf and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(s.bi_buf) shr 8);;
    Inc(s.pending);

    s.bi_buf := ush(value) shr (Buf_size - s.bi_valid);
    Inc(s.bi_valid, length - Buf_size);
  end
  else
  begin
    s.bi_buf := s.bi_buf or TsgInteger(value shl s.bi_valid);
    Inc(s.bi_valid, length);
  end;
  {$IFDEF NoOverflowCheck} {$Q+} {$UNDEF NoOverflowCheck} {$ENDIF}
  {$IFDEF NoRangeCheck} {$Q+} {$UNDEF NoRangeCheck} {$ENDIF}
end;

{$else} { !DEBUG }


macro send_code(s, c, tree)
begin
  send_bits(s, tree[c].Code, tree[c].Len);
  { Send a code of the given tree. c and tree must not have side effects }
end

macro send_bits(s, value, length) \
begin TsgInteger len := length;\
  if (s^.bi_valid > (TsgInteger)Buf_size - len) begin\
    TsgInteger val := value;\
    s^.bi_buf |= (val << s^.bi_valid);\
    {put_short(s, s.bi_buf);}
    s.pending_buf^[s.pending] := uch(s.bi_buf and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(s.bi_buf) shr 8);;
    Inc(s.pending);

    s^.bi_buf := (ush)val >> (Buf_size - s^.bi_valid);\
    s^.bi_valid += len - Buf_size;\
  end else begin\
    s^.bi_buf |= (value) << s^.bi_valid;\
    s^.bi_valid += len;\
  end\
end;
{$endif} { DEBUG }

{ ===========================================================================
  Reverse the first len bits of a code, using straightforward code (a faster
  method would use a table)
  IN assertion: 1 <= len <= 15 }

{local}
function bi_reverse(code : TsgUnsignedInt;         { the value to invert }
                    len : TsgInteger) : TsgUnsignedInt;   { its bit length }

var
  res : TsgUnsignedInt; {register}
begin
  res := 0;
  repeat
    res := res or (code and 1);
    code := code shr 1;
    res := res shl 1;
    Dec(len);
  until (len <= 0);
  bi_reverse := res shr 1;
end;

{ ===========================================================================
  Generate the codes for a given tree and bit counts (which need not be
  optimal).
  IN assertion: the array bl_count contains the bit length statistics for
  the given tree and the field len is set for all tree elements.
  OUT assertion: the field code is set for all tree elements of non
      zero code length. }

{local}
procedure gen_codes(tree : tree_ptr;  { the tree to decorate }
                    max_code : TsgInteger;   { largest code with non zero frequency }
                    var bl_count : array of ushf);  { number of codes at each bit length }

var
  next_code : array[0..MAX_BITS+1-1] of ush; { next code value for each bit length }
  code : ush;              { running code value }
  bits : TsgInteger;                  { bit index }
  n : TsgInteger;                     { code index }
var
  len : TsgInteger;
begin
  code := 0;

  { The distribution counts are first used to generate the code values
    without bit reversal. }

  for bits := 1 to MAX_BITS do
  begin
    code := ((code + bl_count[bits-1]) shl 1);
    next_code[bits] := code;
  end;
  { Check that the bit counts in bl_count are consistent. The last code
    must be all ones. }

  {$IFDEF DEBUG}
  Assert (code + bl_count[MAX_BITS]-1 = (1 shl MAX_BITS)-1,
          'inconsistent bit counts');
  Tracev(#13'gen_codes: max_code '+IntToStr(max_code));
  {$ENDIF}

  for n := 0 to max_code do
  begin
    len := tree^[n].dl.Len;
    if (len = 0) then
      continue;
    { Now reverse the bits }
    tree^[n].fc.Code := bi_reverse(next_code[len], len);
    Inc(next_code[len]);
    {$ifdef DEBUG}
    if (n>31) and (n<128) then
      Tracecv(tree <> tree_ptr(@static_ltree),
       (^M'n #'+IntToStr(n)+' '+AnsiChar(n)+' l '+IntToStr(len)+' c '+
         IntToStr(tree^[n].fc.Code)+' ('+IntToStr(next_code[len]-1)+')'))
    else
      Tracecv(tree <> tree_ptr(@static_ltree),
      (^M'n #'+IntToStr(n)+'   l '+IntToStr(len)+' c '+
         IntToStr(tree^[n].fc.Code)+' ('+IntToStr(next_code[len]-1)+')'));
    {$ENDIF}
  end;
end;

{ ===========================================================================
  Genererate the file trees.h describing the static trees. }
{$ifdef GEN_TREES_H}

macro SEPARATOR(i, last, width)
  if (i) = (last) then
    ( ^M');'^M^M
  else    \
    if (i) mod (width) = (width)-1 then
       ','^M
     else
       ', '

procedure gen_trees_header;
var
  header : system.text;
  i : TsgInteger;
begin
  system.assign(header, 'trees.inc');
  {$I-}
  ReWrite(header);
  {$I+}
  Assert (IOresult <> 0, 'Can''t open trees.h');
  WriteLn(header,
    '{ header created automatically with -DGEN_TREES_H }'^M);

  WriteLn(header, 'local const ct_data static_ltree[L_CODES+2] := (');
  for i := 0 to L_CODES+2-1 do
  begin
    WriteLn(header, '((%3u),(%3u))%s', static_ltree[i].Code,
		static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
  end;

  WriteLn(header, 'local const ct_data static_dtree[D_CODES] := (');
  for i := 0 to D_CODES-1 do
  begin
    WriteLn(header, '((%2u),(%2u))%s', static_dtree[i].Code,
		static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
  end;

  WriteLn(header, 'const uch _dist_code[DIST_CODE_LEN] := (');
  for i := 0 to DIST_CODE_LEN-1 do
  begin
    WriteLn(header, '%2u%s', _dist_code[i],
		SEPARATOR(i, DIST_CODE_LEN-1, 20));
  end;

  WriteLn(header, 'const uch _length_code[MAX_MATCH-MIN_MATCH+1]= (');
  for i := 0 to MAX_MATCH-MIN_MATCH+1-1 do
  begin
    WriteLn(header, '%2u%s', _length_code[i],
		SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
  end;

  WriteLn(header, 'local const int base_length[LENGTH_CODES] := (');
  for i := 0 to LENGTH_CODES-1 do
  begin
    WriteLn(header, '%1u%s', base_length[i],
		SEPARATOR(i, LENGTH_CODES-1, 20));
  end;

  WriteLn(header, 'local const int base_dist[D_CODES] := (');
  for i := 0 to D_CODES-1 do
  begin
    WriteLn(header, '%5u%s', base_dist[i],
		SEPARATOR(i, D_CODES-1, 10));
  end;

  close(header);
end;
{$endif} { GEN_TREES_H }


{ ===========================================================================
  Initialize the various 'constant' tables. }

{local}
procedure tr_static_init;

{$ifdef GEN_TREES_H}
const
  static_init_done : boolean = FALSE;
var
  n : TsgInteger;        { iterates over tree elements }
  bits : TsgInteger;     { bit counter }
  length : TsgInteger;   { length value }
  code : TsgInteger;     { code value }
  dist : TsgInteger;     { distance index }
  bl_count : array[0..MAX_BITS+1-1] of ush;
    { number of codes at each bit length for an optimal tree }
begin
    if (static_init_done) then
      exit;

    { Initialize the mapping length (0..255) -> length code (0..28) }
    length := 0;
    for code := 0 to LENGTH_CODES-1-1 do
    begin
      base_length[code] := length;
      for n := 0 to (1 shl extra_lbits[code])-1 do
      begin
        _length_code[length] := uch(code);
        Inc(length);
      end;
    end;
    Assert (length = 256, 'tr_static_init: length <> 256');
    { Note that the length 255 (match length 258) can be represented
      in two different ways: code 284 + 5 bits or code 285, so we
      overwrite length_code[255] to use the best encoding: }

    _length_code[length-1] := uch(code);

    { Initialize the mapping dist (0..32K) -> dist code (0..29) }
    dist := 0;
    for code := 0 to 16-1 do
    begin
      base_dist[code] := dist;
      for n := 0 to (1 shl extra_dbits[code])-1 do
      begin
        _dist_code[dist] := uch(code);
        Inc(dist);
      end;
    end;
    Assert (dist = 256, 'tr_static_init: dist <> 256');
    dist := dist shr 7; { from now on, all distances are divided by 128 }
    for code := 16 to D_CODES-1 do
    begin
      base_dist[code] := dist shl 7;
      for n := 0 to (1 shl (extra_dbits[code]-7))-1 do
      begin
        _dist_code[256 + dist] := uch(code);
        Inc(dist);
      end;
    end;
    Assert (dist = 256, 'tr_static_init: 256+dist <> 512');

    { Construct the codes of the static literal tree }
    for bits := 0 to MAX_BITS do
      bl_count[bits] := 0;
    n := 0;
    while (n <= 143) do
    begin
      static_ltree[n].dl.Len := 8;
      Inc(n);
      Inc(bl_count[8]);
    end;
    while (n <= 255) do
    begin
      static_ltree[n].dl.Len := 9;
      Inc(n);
      Inc(bl_count[9]);
    end;
    while (n <= 279) do
    begin
      static_ltree[n].dl.Len := 7;
      Inc(n);
      Inc(bl_count[7]);
    end;
    while (n <= 287) do
    begin
      static_ltree[n].dl.Len := 8;
      Inc(n);
      Inc(bl_count[8]);
    end;

    { Codes 286 and 287 do not exist, but we must include them in the
      tree construction to get a canonical Huffman tree (longest code
      all ones)  }

    gen_codes(tree_ptr(@static_ltree), L_CODES+1, bl_count);

    { The static distance tree is trivial: }
    for n := 0 to D_CODES-1 do
    begin
      static_dtree[n].dl.Len := 5;
      static_dtree[n].fc.Code := bi_reverse(TsgUnsignedInt(n), 5);
    end;
    static_init_done := TRUE;

    gen_trees_header;  { save to include file }
{$else}
begin
{$endif} { GEN_TREES_H) }
end;

{ ===========================================================================
  Initialize a new block. }
{local}

procedure init_block(var s : deflate_state);
var
  n : TsgInteger; { iterates over tree elements }
begin
  { Initialize the trees. }
  for n := 0 to L_CODES-1 do
    s.dyn_ltree[n].fc.Freq := 0;
  for n := 0 to D_CODES-1 do
    s.dyn_dtree[n].fc.Freq := 0;
  for n := 0 to BL_CODES-1 do
    s.bl_tree[n].fc.Freq := 0;

  s.dyn_ltree[END_BLOCK].fc.Freq := 1;
  s.static_len := Long(0);
  s.opt_len := Long(0);
  s.matches := 0;
  s.last_lit := 0;
end;

const
  SMALLEST = 1;
{ Index within the heap array of least frequent node in the Huffman tree }

{ ===========================================================================
  Initialize the tree data structures for a new zlib stream. }
procedure _tr_init(var s : deflate_state);
begin
  tr_static_init;

  s.compressed_len := Long(0);

  s.l_desc.dyn_tree := tree_ptr(@s.dyn_ltree);
  s.l_desc.stat_desc := @static_l_desc;

  s.d_desc.dyn_tree := tree_ptr(@s.dyn_dtree);
  s.d_desc.stat_desc := @static_d_desc;

  s.bl_desc.dyn_tree := tree_ptr(@s.bl_tree);
  s.bl_desc.stat_desc := @static_bl_desc;

  s.bi_buf := 0;
  s.bi_valid := 0;
  s.last_eob_len := 8; { enough lookahead for inflate }
{$ifdef DEBUG}
  s.bits_sent := Long(0);
{$endif}

  { Initialize the first block of the first file: }
  init_block(s);
end;

{ ===========================================================================
  Remove the smallest element from the heap and recreate the heap with
  one less element. Updates heap and heap_len.

macro pqremove(s, tree, top)
begin
    top := s.heap[SMALLEST];
    s.heap[SMALLEST] := s.heap[s.heap_len];
    Dec(s.heap_len);
    pqdownheap(s, tree, SMALLEST);
end
}

{ ===========================================================================
  Compares to subtrees, using the tree depth as tie breaker when
  the subtrees have equal frequency. This minimizes the worst case length.

macro smaller(tree, n, m, depth)
   ( (tree[n].Freq < tree[m].Freq) or
     ((tree[n].Freq = tree[m].Freq) and (depth[n] <= depth[m])) )
}

{ ===========================================================================
  Restore the heap property by moving down the tree starting at node k,
  exchanging a node with the smallest of its two sons if necessary, stopping
  when the heap property is re-established (each father smaller than its
  two sons). }
{local}

procedure pqdownheap(var s : deflate_state;
                     var tree : tree_type;   { the tree to restore }
                     k : TsgInteger);          { node to move down }
var
  v : TsgInteger;
  j : TsgInteger;
begin
  v := s.heap[k];
  j := k shl 1;  { left son of k }
  while (j <= s.heap_len) do
  begin
    { Set j to the smallest of the two sons: }
    if (j < s.heap_len) and
       {smaller(tree, s.heap[j+1], s.heap[j], s.depth)}
      ( (tree[s.heap[j+1]].fc.Freq < tree[s.heap[j]].fc.Freq) or
        ((tree[s.heap[j+1]].fc.Freq = tree[s.heap[j]].fc.Freq) and
         (s.depth[s.heap[j+1]] <= s.depth[s.heap[j]])) ) then
    begin
      Inc(j);
    end;
    { Exit if v is smaller than both sons }
    if {(smaller(tree, v, s.heap[j], s.depth))}
     ( (tree[v].fc.Freq < tree[s.heap[j]].fc.Freq) or
       ((tree[v].fc.Freq = tree[s.heap[j]].fc.Freq) and
        (s.depth[v] <= s.depth[s.heap[j]])) ) then
      break;
    { Exchange v with the smallest son }
    s.heap[k] := s.heap[j];
    k := j;

    { And continue down the tree, setting j to the left son of k }
    j := j shl 1;
  end;
  s.heap[k] := v;
end;

{ ===========================================================================
  Compute the optimal bit lengths for a tree and update the total bit length
  for the current block.
  IN assertion: the fields freq and dad are set, heap[heap_max] and
     above are the tree nodes sorted by increasing frequency.
  OUT assertions: the field len is set to the optimal bit length, the
      array bl_count contains the frequencies for each bit length.
      The length opt_len is updated; static_len is also updated if stree is
      not null. }

{local}
procedure gen_bitlen(var s : deflate_state;
                     var desc : tree_desc);   { the tree descriptor }
var
  tree : tree_ptr;
  max_code : TsgInteger;
  stree : tree_ptr; {const}
  extra : pzIntfArray; {const}
  base : TsgInteger;
  max_length : TsgInteger;
  h : TsgInteger;              { heap index }
  n, m : TsgInteger;           { iterate over the tree elements }
  bits : TsgInteger;           { bit length }
  xbits : TsgInteger;          { extra bits }
  f : ush;              { frequency }
  overflow : TsgInteger;   { number of elements with bit length too large }
begin
  tree := desc.dyn_tree;
  max_code := desc.max_code;
  stree := desc.stat_desc^.static_tree;
  extra := desc.stat_desc^.extra_bits;
  base := desc.stat_desc^.extra_base;
  max_length := desc.stat_desc^.max_length;
  overflow := 0;

  for bits := 0 to MAX_BITS do
    s.bl_count[bits] := 0;

  { In a first pass, compute the optimal bit lengths (which may
    overflow in the case of the bit length tree). }

  tree^[s.heap[s.heap_max]].dl.Len := 0; { root of the heap }

  for h := s.heap_max+1 to HEAP_SIZE-1 do
  begin
    n := s.heap[h];
    bits := tree^[tree^[n].dl.Dad].dl.Len + 1;
    if (bits > max_length) then
    begin
      bits := max_length;
      Inc(overflow);
    end;
    tree^[n].dl.Len := ush(bits);
    { We overwrite tree[n].dl.Dad which is no longer needed }

    if (n > max_code) then
      continue; { not a leaf node }

    Inc(s.bl_count[bits]);
    xbits := 0;
    if (n >= base) then
      xbits := extra^[n-base];
    f := tree^[n].fc.Freq;
    Inc(s.opt_len, ulg(f) * (bits + xbits));
    if (stree <> NIL) then
      Inc(s.static_len, ulg(f) * (stree^[n].dl.Len + xbits));
  end;
  if (overflow = 0) then
    exit;
  {$ifdef DEBUG}
  Tracev(^M'bit length overflow');
  {$endif}
  { This happens for example on obj2 and pic of the Calgary corpus }

  { Find the first bit length which could increase: }
  repeat
    bits := max_length-1;
    while (s.bl_count[bits] = 0) do
      Dec(bits);
    Dec(s.bl_count[bits]);      { move one leaf down the tree }
    Inc(s.bl_count[bits+1], 2); { move one overflow item as its brother }
    Dec(s.bl_count[max_length]);
    { The brother of the overflow item also moves one step up,
      but this does not affect bl_count[max_length] }

    Dec(overflow, 2);
  until (overflow <= 0);

  { Now recompute all bit lengths, scanning in increasing frequency.
    h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
    lengths instead of fixing only the wrong ones. This idea is taken
    from 'ar' written by Haruhiko Okumura.) }
  h := HEAP_SIZE;  { Delphi3: compiler warning w/o this }
  for bits := max_length downto 1 do
  begin
    n := s.bl_count[bits];
    while (n <> 0) do
    begin
      Dec(h);
      m := s.heap[h];
      if (m > max_code) then
        continue;
      if (tree^[m].dl.Len <> TsgUnsignedInt(bits)) then
      begin
        {$ifdef DEBUG}
        Trace('code '+IntToStr(m)+' bits '+IntToStr(tree^[m].dl.Len)
              +'.'+IntToStr(bits));
        {$ENDIF}
        Inc(s.opt_len, (long(bits) - long(tree^[m].dl.Len))
                        * long(tree^[m].fc.Freq) );
        tree^[m].dl.Len := ush(bits);
      end;
      Dec(n);
    end;
  end;
end;

{ ===========================================================================
  Construct one Huffman tree and assigns the code bit strings and lengths.
  Update the total bit length for the current block.
  IN assertion: the field freq is set for all tree elements.
  OUT assertions: the fields len and code are set to the optimal bit length
      and corresponding code. The length opt_len is updated; static_len is
      also updated if stree is not null. The field max_code is set. }

{local}
procedure build_tree(var s : deflate_state;
                     var desc : tree_desc); { the tree descriptor }

var
  tree : tree_ptr;
  stree : tree_ptr; {const}
  elems : TsgInteger;
  n, m : TsgInteger;          { iterate over heap elements }
  max_code : TsgInteger;      { largest code with non zero frequency }
  node : TsgInteger;          { new node being created }
begin
  tree := desc.dyn_tree;
  stree := desc.stat_desc^.static_tree;
  elems := desc.stat_desc^.elems;
  max_code := -1;

  { Construct the initial heap, with least frequent element in
    heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
    heap[0] is not used. }
  s.heap_len := 0;
  s.heap_max := HEAP_SIZE;

  for n := 0 to elems-1 do
  begin
    if (tree^[n].fc.Freq <> 0) then
    begin
      max_code := n;
      Inc(s.heap_len);
      s.heap[s.heap_len] := n;
      s.depth[n] := 0;
    end
    else
    begin
      tree^[n].dl.Len := 0;
    end;
  end;

  { The pkzip format requires that at least one distance code exists,
    and that at least one bit should be sent even if there is only one
    possible code. So to avoid special checks later on we force at least
    two codes of non zero frequency. }

  while (s.heap_len < 2) do
  begin
    Inc(s.heap_len);
    if (max_code < 2) then
    begin
      Inc(max_code);
      s.heap[s.heap_len] := max_code;
      node := max_code;
    end
    else
    begin
      s.heap[s.heap_len] := 0;
      node := 0;
    end;
    tree^[node].fc.Freq := 1;
    s.depth[node] := 0;
    Dec(s.opt_len);
    if (stree <> NIL) then
      Dec(s.static_len, stree^[node].dl.Len);
    { node is 0 or 1 so it does not have extra bits }
  end;
  desc.max_code := max_code;

  { The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
    establish sub-heaps of increasing lengths: }

  for n := s.heap_len div 2 downto 1 do
    pqdownheap(s, tree^, n);

  { Construct the Huffman tree by repeatedly combining the least two
    frequent nodes. }

  node := elems;              { next internal node of the tree }
  repeat
    {pqremove(s, tree, n);}  { n := node of least frequency }
    n := s.heap[SMALLEST];
    s.heap[SMALLEST] := s.heap[s.heap_len];
    Dec(s.heap_len);
    pqdownheap(s, tree^, SMALLEST);

    m := s.heap[SMALLEST]; { m := node of next least frequency }

    Dec(s.heap_max);
    s.heap[s.heap_max] := n; { keep the nodes sorted by frequency }
    Dec(s.heap_max);
    s.heap[s.heap_max] := m;

    { Create a new node father of n and m }
    tree^[node].fc.Freq := tree^[n].fc.Freq + tree^[m].fc.Freq;
    { maximum }
    if (s.depth[n] >= s.depth[m]) then
      s.depth[node] := uch (s.depth[n] + 1)
    else
      s.depth[node] := uch (s.depth[m] + 1);

    tree^[m].dl.Dad := ush(node);
    tree^[n].dl.Dad := ush(node);
{$ifdef DUMP_BL_TREE}
    if (tree = tree_ptr(@s.bl_tree)) then
    begin
      WriteLn(#13'node ',node,'(',tree^[node].fc.Freq,') sons ',n,
              '(',tree^[n].fc.Freq,') ', m, '(',tree^[m].fc.Freq,')');
    end;
{$endif}
    { and insert the new node in the heap }
    s.heap[SMALLEST] := node;
    Inc(node);
    pqdownheap(s, tree^, SMALLEST);

  until (s.heap_len < 2);

  Dec(s.heap_max);
  s.heap[s.heap_max] := s.heap[SMALLEST];

  { At this point, the fields freq and dad are set. We can now
    generate the bit lengths. }

  gen_bitlen(s, desc);

  { The field len is now set, we can generate the bit codes }
  gen_codes (tree, max_code, s.bl_count);
end;

{ ===========================================================================
  Scan a literal or distance tree to determine the frequencies of the codes
  in the bit length tree. }

{local}
procedure scan_tree(var s : deflate_state;
                    var tree : array of ct_data;    { the tree to be scanned }
                    max_code : TsgInteger);    { and its largest code of non zero frequency }
var
  n : TsgInteger;                 { iterates over all tree elements }
  prevlen : TsgInteger;           { last emitted length }
  curlen : TsgInteger;            { length of current code }
  nextlen : TsgInteger;           { length of next code }
  count : TsgInteger;             { repeat count of the current code }
  max_count : TsgInteger;         { max repeat count }
  min_count : TsgInteger;         { min repeat count }
begin
  prevlen := -1;
  nextlen := tree[0].dl.Len;
  count := 0;
  max_count := 7;
  min_count := 4;

  if (nextlen = 0) then
  begin
    max_count := 138;
    min_count := 3;
  end;
  tree[max_code+1].dl.Len := ush($ffff); { guard }

  for n := 0 to max_code do
  begin
    curlen := nextlen;
    nextlen := tree[n+1].dl.Len;
    Inc(count);
    if (count < max_count) and (curlen = nextlen) then
      continue
    else
      if (count < min_count) then
        Inc(s.bl_tree[curlen].fc.Freq, count)
      else
        if (curlen <> 0) then
        begin
          if (curlen <> prevlen) then
            Inc(s.bl_tree[curlen].fc.Freq);
          Inc(s.bl_tree[REP_3_6].fc.Freq);
        end
        else
          if (count <= 10) then
            Inc(s.bl_tree[REPZ_3_10].fc.Freq)
          else
            Inc(s.bl_tree[REPZ_11_138].fc.Freq);

    count := 0;
    prevlen := curlen;
    if (nextlen = 0) then
    begin
      max_count := 138;
      min_count := 3;
    end
    else
      if (curlen = nextlen) then
      begin
        max_count := 6;
        min_count := 3;
      end
      else
      begin
        max_count := 7;
        min_count := 4;
      end;
  end;
end;

{ ===========================================================================
  Send a literal or distance tree in compressed form, using the codes in
  bl_tree. }

{local}
procedure send_tree(var s : deflate_state;
                    var tree : array of ct_data;    { the tree to be scanned }
                    max_code : TsgInteger);    { and its largest code of non zero frequency }

var
  n : TsgInteger;                { iterates over all tree elements }
  prevlen : TsgInteger;          { last emitted length }
  curlen : TsgInteger;           { length of current code }
  nextlen : TsgInteger;          { length of next code }
  count : TsgInteger;            { repeat count of the current code }
  max_count : TsgInteger;        { max repeat count }
  min_count : TsgInteger;        { min repeat count }
begin
  prevlen := -1;
  nextlen := tree[0].dl.Len;
  count := 0;
  max_count := 7;
  min_count := 4;

  { tree[max_code+1].dl.Len := -1; }  { guard already set }
  if (nextlen = 0) then
  begin
    max_count := 138;
    min_count := 3;
  end;

  for n := 0 to max_code do
  begin
    curlen := nextlen;
    nextlen := tree[n+1].dl.Len;
    Inc(count);
    if (count < max_count) and (curlen = nextlen) then
      continue
    else
      if (count < min_count) then
      begin
        repeat
          {$ifdef DEBUG}
          Tracevvv(#13'cd '+IntToStr(curlen));
          {$ENDIF}
          send_bits(s, s.bl_tree[curlen].fc.Code, s.bl_tree[curlen].dl.Len);
          Dec(count);
        until (count = 0);
      end
      else
        if (curlen <> 0) then
        begin
          if (curlen <> prevlen) then
          begin
            {$ifdef DEBUG}
            Tracevvv(#13'cd '+IntToStr(curlen));
            {$ENDIF}
            send_bits(s, s.bl_tree[curlen].fc.Code, s.bl_tree[curlen].dl.Len);
            Dec(count);
          end;
          {$IFDEF DEBUG}
          Assert((count >= 3) and (count <= 6), ' 3_6?');
          {$ENDIF}
          {$ifdef DEBUG}
          Tracevvv(#13'cd '+IntToStr(REP_3_6));
          {$ENDIF}
          send_bits(s, s.bl_tree[REP_3_6].fc.Code, s.bl_tree[REP_3_6].dl.Len);
          send_bits(s, count-3, 2);
        end
        else
          if (count <= 10) then
          begin
            {$ifdef DEBUG}
            Tracevvv(#13'cd '+IntToStr(REPZ_3_10));
            {$ENDIF}
            send_bits(s, s.bl_tree[REPZ_3_10].fc.Code, s.bl_tree[REPZ_3_10].dl.Len);
            send_bits(s, count-3, 3);
          end
          else
          begin
            {$ifdef DEBUG}
            Tracevvv(#13'cd '+IntToStr(REPZ_11_138));
            {$ENDIF}
            send_bits(s, s.bl_tree[REPZ_11_138].fc.Code, s.bl_tree[REPZ_11_138].dl.Len);
            send_bits(s, count-11, 7);
          end;
    count := 0;
    prevlen := curlen;
    if (nextlen = 0) then
    begin
      max_count := 138;
      min_count := 3;
    end
    else
      if (curlen = nextlen) then
      begin
        max_count := 6;
        min_count := 3;
      end
      else
      begin
        max_count := 7;
        min_count := 4;
      end;
  end;
end;

{ ===========================================================================
  Construct the Huffman tree for the bit lengths and return the index in
  bl_order of the last bit length code to send. }

{local}
function build_bl_tree(var s : deflate_state) : TsgInteger;
var
  max_blindex : TsgInteger;  { index of last bit length code of non zero freq }
begin
  { Determine the bit length frequencies for literal and distance trees }
  scan_tree(s, s.dyn_ltree, s.l_desc.max_code);
  scan_tree(s, s.dyn_dtree, s.d_desc.max_code);

  { Build the bit length tree: }
  build_tree(s, s.bl_desc);
  { opt_len now includes the length of the tree representations, except
    the lengths of the bit lengths codes and the 5+5+4 bits for the counts. }

  { Determine the number of bit length codes to send. The pkzip format
    requires that at least 4 bit length codes be sent. (appnote.txt says
    3 but the actual value used is 4.) }

  for max_blindex := BL_CODES-1 downto 3 do
  begin
    if (s.bl_tree[bl_order[max_blindex]].dl.Len <> 0) then
      break;
  end;
  { Update opt_len to include the bit length tree and counts }
  Inc(s.opt_len, 3*(max_blindex+1) + 5+5+4);
  {$ifdef DEBUG}
  Tracev(^M'dyn trees: dyn %ld, stat %ld {s.opt_len, s.static_len}');
  {$ENDIF}

  build_bl_tree := max_blindex;
end;

{ ===========================================================================
  Send the header for a block using dynamic Huffman trees: the counts, the
  lengths of the bit length codes, the literal tree and the distance tree.
  IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. }

{local}
procedure send_all_trees(var s : deflate_state;
                         lcodes : TsgInteger;
                         dcodes : TsgInteger;
                         blcodes : TsgInteger); { number of codes for each tree }
var
  rank : TsgInteger;                    { index in bl_order }
begin
  {$IFDEF DEBUG}
  Assert ((lcodes >= 257) and (dcodes >= 1) and (blcodes >= 4),
          'not enough codes');
  Assert ((lcodes <= L_CODES) and (dcodes <= D_CODES)
          and (blcodes <= BL_CODES), 'too many codes');
  Tracev(^M'bl counts: ');
  {$ENDIF}
  send_bits(s, lcodes-257, 5); { not +255 as stated in appnote.txt }
  send_bits(s, dcodes-1,   5);
  send_bits(s, blcodes-4,  4); { not -3 as stated in appnote.txt }
  for rank := 0 to blcodes-1 do
  begin
    {$ifdef DEBUG}
    Tracev(^M'bl code '+IntToStr(bl_order[rank]));
    {$ENDIF}
    send_bits(s, s.bl_tree[bl_order[rank]].dl.Len, 3);
  end;
  {$ifdef DEBUG}
  Tracev(^M'bl tree: sent '+IntToStr(s.bits_sent));
  {$ENDIF}

  send_tree(s, s.dyn_ltree, lcodes-1); { literal tree }
  {$ifdef DEBUG}
  Tracev(^M'lit tree: sent '+IntToStr(s.bits_sent));
  {$ENDIF}

  send_tree(s, s.dyn_dtree, dcodes-1); { distance tree }
  {$ifdef DEBUG}
  Tracev(^M'dist tree: sent '+IntToStr(s.bits_sent));
  {$ENDIF}
end;

{ ===========================================================================
  Flush the bit buffer and align the output on a byte boundary }

{local}
procedure bi_windup(var s : deflate_state);
begin
  if (s.bi_valid > 8) then
  begin
    {put_short(s, s.bi_buf);}
    s.pending_buf^[s.pending] := uch(s.bi_buf and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(s.bi_buf) shr 8);;
    Inc(s.pending);
  end
  else
    if (s.bi_valid > 0) then
    begin
      {put_byte(s, (Byte)s^.bi_buf);}
      s.pending_buf^[s.pending] := Byte(s.bi_buf);
      Inc(s.pending);
    end;
  s.bi_buf := 0;
  s.bi_valid := 0;
{$ifdef DEBUG}
  s.bits_sent := (s.bits_sent+7) and (not 7);
{$endif}
end;

{ ===========================================================================
  Copy a stored block, storing first the length and its
  one's complement if requested. }

{local}
procedure copy_block(var s : deflate_state;
                     buf : pcharf;      { the input data }
                     len : TsgUnsignedInt;    { its length }
                     header : boolean); { true if block header must be written }
begin
  bi_windup(s);        { align on byte boundary }
  s.last_eob_len := 8; { enough lookahead for inflate }

  if (header) then
  begin
    {put_short(s, (ush)len);}
    s.pending_buf^[s.pending] := uch(ush(len) and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(len) shr 8);;
    Inc(s.pending);
    {put_short(s, (ush)~len);}
    s.pending_buf^[s.pending] := uch(ush(not len) and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(not len) shr 8);;
    Inc(s.pending);

{$ifdef DEBUG}
    Inc(s.bits_sent, 2*16);
{$endif}
  end;
{$ifdef DEBUG}
  Inc(s.bits_sent, ulg(len shl 3));
{$endif}
  while (len <> 0) do
  begin
    Dec(len);
    {put_byte(s, *buf++);}
    s.pending_buf^[s.pending] := buf^;
    Inc(buf);
    Inc(s.pending);
  end;
end;


{ ===========================================================================
  Send a stored block }

procedure _tr_stored_block(var s : deflate_state;
                           buf : pcharf;     { input block }
                           stored_len : ulg; { length of input block }
                           eof : boolean);   { true if this is the last block for a file }

begin
  send_bits(s, (STORED_BLOCK shl 1)+ord(eof), 3);  { send block type }
  s.compressed_len := (s.compressed_len + 3 + 7) and ulg(not Long(7));
  Inc(s.compressed_len, (stored_len + 4) shl 3);

  copy_block(s, buf, TsgUnsignedInt(stored_len), TRUE); { with header }
end;

{ ===========================================================================
  Flush the bit buffer, keeping at most 7 bits in it. }

{local}
procedure bi_flush(var s : deflate_state);
begin
  if (s.bi_valid = 16) then
  begin
    {put_short(s, s.bi_buf);}
    s.pending_buf^[s.pending] := uch(s.bi_buf and $ff);
    Inc(s.pending);
    s.pending_buf^[s.pending] := uch(ush(s.bi_buf) shr 8);;
    Inc(s.pending);

    s.bi_buf := 0;
    s.bi_valid := 0;
  end
  else
   if (s.bi_valid >= 8) then
   begin
     {put_byte(s, (Byte)s^.bi_buf);}
     s.pending_buf^[s.pending] := Byte(s.bi_buf);
     Inc(s.pending);

     s.bi_buf := s.bi_buf shr 8;
     Dec(s.bi_valid, 8);
   end;
end;


{ ===========================================================================
  Send one empty static block to give enough lookahead for inflate.
  This takes 10 bits, of which 7 may remain in the bit buffer.
  The current inflate code requires 9 bits of lookahead. If the
  last two codes for the previous block (real code plus EOB) were coded
  on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
  the last real code. In this case we send two empty static blocks instead
  of one. (There are no problems if the previous block is stored or fixed.)
  To simplify the code, we assume the worst case of last real code encoded
  on one bit only. }

procedure _tr_align(var s : deflate_state);
begin
  send_bits(s, STATIC_TREES shl 1, 3);
  {$ifdef DEBUG}
  Tracevvv(#13'cd '+IntToStr(END_BLOCK));
  {$ENDIF}
  send_bits(s, static_ltree[END_BLOCK].fc.Code, static_ltree[END_BLOCK].dl.Len);
  Inc(s.compressed_len, Long(10)); { 3 for block type, 7 for EOB }
  bi_flush(s);
  { Of the 10 bits for the empty block, we have already sent
    (10 - bi_valid) bits. The lookahead for the last real code (before
    the EOB of the previous block) was thus at least one plus the length
    of the EOB plus what we have just sent of the empty static block. }
  if (1 + s.last_eob_len + 10 - s.bi_valid < 9) then
  begin
    send_bits(s, STATIC_TREES shl 1, 3);
    {$ifdef DEBUG}
    Tracevvv(#13'cd '+IntToStr(END_BLOCK));
    {$ENDIF}
    send_bits(s, static_ltree[END_BLOCK].fc.Code, static_ltree[END_BLOCK].dl.Len);
    Inc(s.compressed_len, Long(10));
    bi_flush(s);
  end;
  s.last_eob_len := 7;
end;

{ ===========================================================================
  Set the data type to ASCII or BINARY, using a crude approximation:
  binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
  IN assertion: the fields freq of dyn_ltree are set and the total of all
  frequencies does not exceed 64K (to fit in an int on 16 bit machines). }

{local}
procedure set_data_type(var s : deflate_state);
var
  n : TsgInteger;
  ascii_freq : TsgUnsignedInt;
  bin_freq : TsgUnsignedInt;
begin
  n := 0;
  ascii_freq := 0;
  bin_freq := 0;

  while (n < 7) do
  begin
    Inc(bin_freq, s.dyn_ltree[n].fc.Freq);
    Inc(n);
  end;
  while (n < 128) do
  begin
    Inc(ascii_freq, s.dyn_ltree[n].fc.Freq);
    Inc(n);
  end;
  while (n < LITERALS) do
  begin
    Inc(bin_freq, s.dyn_ltree[n].fc.Freq);
    Inc(n);
  end;
  if (bin_freq > (ascii_freq shr 2)) then
    s.data_type := Byte(Z_BINARY)
  else
    s.data_type := Byte(Z_ASCII);
end;

{ ===========================================================================
  Send the block data compressed using the given Huffman trees }

{local}
procedure compress_block(var s : deflate_state;
                         var ltree : array of ct_data;   { literal tree }
                         var dtree : array of ct_data);  { distance tree }
var
  dist : TsgUnsignedInt;      { distance of matched AnsiString }
  lc : TsgInteger;             { match length or unmatched AnsiChar (if dist == 0) }
  lx : TsgUnsignedInt;        { running index in l_buf }
  code : TsgUnsignedInt;      { the code to send }
  extra : TsgInteger;          { number of extra bits to send }
begin
  lx := 0;
  if (s.last_lit <> 0) then
  repeat
    dist := s.d_buf^[lx];
    lc := s.l_buf^[lx];
    Inc(lx);
    if (dist = 0) then
    begin
      { send a literal byte }
      {$ifdef DEBUG}
      Tracevvv(#13'cd '+IntToStr(lc));
      Tracecv((lc > 31) and (lc < 128), ' '+AnsiChar(lc)+' ');
      {$ENDIF}
      send_bits(s, ltree[lc].fc.Code, ltree[lc].dl.Len);
    end
    else
    begin
      { Here, lc is the match length - MIN_MATCH }
      code := _length_code[lc];
      { send the length code }
      {$ifdef DEBUG}
      Tracevvv(#13'cd '+IntToStr(code+LITERALS+1));
      {$ENDIF}
      send_bits(s, ltree[code+LITERALS+1].fc.Code, ltree[code+LITERALS+1].dl.Len);
      extra := extra_lbits[code];
      if (extra <> 0) then
      begin
        Dec(lc, base_length[code]);
        send_bits(s, lc, extra);       { send the extra length bits }
      end;
      Dec(dist); { dist is now the match distance - 1 }
      {code := d_code(dist);}
      if (dist < 256) then
        code := _dist_code[dist]
      else
        code := _dist_code[256+(dist shr 7)];

      {$IFDEF DEBUG}
      Assert (code < D_CODES, 'bad d_code');
      {$ENDIF}

      { send the distance code }
      {$ifdef DEBUG}
      Tracevvv(#13'cd '+IntToStr(code));
      {$ENDIF}
      send_bits(s, dtree[code].fc.Code, dtree[code].dl.Len);
      extra := extra_dbits[code];
      if (extra <> 0) then
      begin
        Dec(dist, base_dist[code]);
        send_bits(s, dist, extra);   { send the extra distance bits }
      end;
    end; { literal or match pair ? }

    { Check that the overlay between pending_buf and d_buf+l_buf is ok: }
    {$IFDEF DEBUG}
    Assert(s.pending < s.lit_bufsize + 2*lx, 'pendingBuf overflow');
    {$ENDIF}
  until (lx >= s.last_lit);

  {$ifdef DEBUG}
  Tracevvv(#13'cd '+IntToStr(END_BLOCK));
  {$ENDIF}
  send_bits(s, ltree[END_BLOCK].fc.Code, ltree[END_BLOCK].dl.Len);
  s.last_eob_len := ltree[END_BLOCK].dl.Len;
end;


{ ===========================================================================
  Determine the best encoding for the current block: dynamic trees, static
  trees or store, and output the encoded block to the zip file. This function
  returns the total compressed length for the file so far. }

function _tr_flush_block (var s : deflate_state;
         buf : pcharf;         { input block, or NULL if too old }
         stored_len : ulg;     { length of input block }
         eof : boolean) : ulg; { true if this is the last block for a file }
var
  opt_lenb, static_lenb : ulg; { opt_len and static_len in bytes }
  max_blindex : TsgInteger;  { index of last bit length code of non zero freq }
begin
  max_blindex := 0;

  { Build the Huffman trees unless a stored block is forced }
  if (s.level > 0) then
  begin
    { Check if the file is ascii or binary }
    if (s.data_type = Z_UNKNOWN) then
      set_data_type(s);

    { Construct the literal and distance trees }
    build_tree(s, s.l_desc);
    {$ifdef DEBUG}
    Tracev(^M'lit data: dyn %ld, stat %ld {s.opt_len, s.static_len}');
    {$ENDIF}

    build_tree(s, s.d_desc);
    {$ifdef DEBUG}
    Tracev(^M'dist data: dyn %ld, stat %ld {s.opt_len, s.static_len}');
    {$ENDIF}
    { At this point, opt_len and static_len are the total bit lengths of
      the compressed block data, excluding the tree representations. }

    { Build the bit length tree for the above two trees, and get the index
      in bl_order of the last bit length code to send. }
    max_blindex := build_bl_tree(s);

    { Determine the best encoding. Compute first the block length in bytes}
    opt_lenb := (s.opt_len+3+7) shr 3;
    static_lenb := (s.static_len+3+7) shr 3;

    {$ifdef DEBUG}
    Tracev(^M'opt %lu(%lu) stat %lu(%lu) stored %lu lit %u '+
	    '{opt_lenb, s.opt_len, static_lenb, s.static_len, stored_len,'+
	    's.last_lit}');
    {$ENDIF}

    if (static_lenb <= opt_lenb) then
      opt_lenb := static_lenb;

  end
  else
  begin
    {$IFDEF DEBUG}
    Assert(buf <> pcharf(NIL), 'lost buf');
    {$ENDIF}
    static_lenb := stored_len + 5;
    opt_lenb := static_lenb;        { force a stored block }
  end;

  { If compression failed and this is the first and last block,
    and if the .zip file can be seeked (to rewrite the local header),
    the whole file is transformed into a stored file:  }

{$ifdef STORED_FILE_OK}
{$ifdef FORCE_STORED_FILE}
  if eof and (s.compressed_len = Long(0)) then
  begin { force stored file }
{$else}
  if (stored_len <= opt_lenb) and eof and (s.compressed_len=Long(0))
     and seekable()) do
  begin
{$endif}
    { Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: }
    if (buf = pcharf(0)) then
      error ('block vanished');

    copy_block(buf, TsgUnsignedInt(stored_len), 0); { without header }
    s.compressed_len := stored_len shl 3;
    s.method := STORED;
  end
  else
{$endif} { STORED_FILE_OK }

{$ifdef FORCE_STORED}
  if (buf <> PAnsiChar(0)) then
  begin { force stored block }
{$else}
  if (stored_len+4 <= opt_lenb) and (buf <> pcharf(0)) then
  begin
                     { 4: two words for the lengths }
{$endif}
    { The test buf <> NULL is only necessary if LIT_BUFSIZE > WSIZE.
      Otherwise we can't have processed more than WSIZE input bytes since
      the last block flush, because compression would have been
      successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
      transform a block into a stored block. }

    _tr_stored_block(s, buf, stored_len, eof);

{$ifdef FORCE_STATIC}
  end
  else
    if (static_lenb >= 0) then
    begin { force static trees }
{$else}
  end
  else
    if (static_lenb = opt_lenb) then
    begin
{$endif}
      send_bits(s, (STATIC_TREES shl 1)+ord(eof), 3);
      compress_block(s, static_ltree, static_dtree);
      Inc(s.compressed_len, 3 + s.static_len);
    end
    else
    begin
      send_bits(s, (DYN_TREES shl 1)+ord(eof), 3);
      send_all_trees(s, s.l_desc.max_code+1, s.d_desc.max_code+1,
                     max_blindex+1);
      compress_block(s, s.dyn_ltree, s.dyn_dtree);
      Inc(s.compressed_len, 3 + s.opt_len);
    end;
  {$ifdef DEBUG}
  Assert (s.compressed_len = s.bits_sent, 'bad compressed size');
  {$ENDIF}
  init_block(s);

  if (eof) then
  begin
    bi_windup(s);
    Inc(s.compressed_len, 7);  { align on byte boundary }
  end;
  {$ifdef DEBUG}
  Tracev(#13'comprlen %lu(%lu) {s.compressed_len shr 3,'+
         's.compressed_len-7*ord(eof)}');
  {$ENDIF}

  _tr_flush_block := s.compressed_len shr 3;
end;


{ ===========================================================================
  Save the match info and tally the frequency counts. Return true if
  the current block must be flushed. }

function _tr_tally (var s : deflate_state;
   dist : TsgUnsignedInt;          { distance of matched AnsiString }
   lc : TsgUnsignedInt) : boolean; { match length-MIN_MATCH or unmatched AnsiChar (if dist=0) }
var
  {$IFDEF DEBUG}
  MAX_DIST : ush;
  {$ENDIF}
  code : ush;
{$ifdef TRUNCATE_BLOCK}
var
  out_length : ulg;
  in_length : ulg;
  dcode : TsgInteger;
{$endif}
begin
  s.d_buf^[s.last_lit] := ush(dist);
  s.l_buf^[s.last_lit] := uch(lc);
  Inc(s.last_lit);
  if (dist = 0) then
  begin
    { lc is the unmatched AnsiChar }
    Inc(s.dyn_ltree[lc].fc.Freq);
  end
  else
  begin
    Inc(s.matches);
    { Here, lc is the match length - MIN_MATCH }
    Dec(dist);             { dist := match distance - 1 }

    {macro d_code(dist)}
    if (dist) < 256 then
      code := _dist_code[dist]
    else
      code := _dist_code[256+(dist shr 7)];
    {$IFDEF DEBUG}
{macro  MAX_DIST(s) <=> ((s)^.w_size-MIN_LOOKAHEAD)
   In order to simplify the code, particularly on 16 bit machines, match
   distances are limited to MAX_DIST instead of WSIZE. }
    MAX_DIST := ush(s.w_size-MIN_LOOKAHEAD);
    Assert((dist < ush(MAX_DIST)) and
           (ush(lc) <= ush(MAX_MATCH-MIN_MATCH)) and
           (ush(code) < ush(D_CODES)),  '_tr_tally: bad match');
    {$ENDIF}
    Inc(s.dyn_ltree[_length_code[lc]+LITERALS+1].fc.Freq);
    {s.dyn_dtree[d_code(dist)].Freq++;}
    Inc(s.dyn_dtree[code].fc.Freq);
  end;

{$ifdef TRUNCATE_BLOCK}
  { Try to guess if it is profitable to stop the current block here }
  if (s.last_lit and $1fff = 0) and (s.level > 2) then
  begin
    { Compute an upper bound for the compressed length }
    out_length := ulg(s.last_lit)*Long(8);
    in_length := ulg(long(s.strstart) - s.block_start);
    for dcode := 0 to D_CODES-1 do
    begin
      Inc(out_length, ulg(s.dyn_dtree[dcode].fc.Freq *
            (Long(5)+extra_dbits[dcode])) );
    end;
    out_length := out_length shr 3;
    {$ifdef DEBUG}
    Tracev(^M'last_lit %u, in %ld, out ~%ld(%ld%%) ');
          { s.last_lit, in_length, out_length,
           Long(100) - out_length*Long(100) div in_length)); }
    {$ENDIF}
    if (s.matches < s.last_lit div 2) and (out_length < in_length div 2) then
    begin
      _tr_tally := TRUE;
      exit;
    end;
  end;
{$endif}
  _tr_tally := (s.last_lit = s.lit_bufsize-1);
  { We avoid equality with lit_bufsize because of wraparound at 64K
    on 16 bit machines and because stored blocks are restricted to
    64K-1 bytes. }
end;

{ Orginal: deflate.h -- internal compression state
           deflate.c -- compress data using the deflation algorithm
  Copyright (C) 1995-1996 Jean-loup Gailly.

  zDeflate.pas Pascal tranlastion
  Copyright (C) 1998 by Jacques Nomssi Nzali
}

const
   deflate_copyright : AnsiString = ' deflate 1.1.2 Copyright 1995-1998 Jean-loup Gailly ';

{  ===========================================================================
   Function prototypes. }

type
   block_state = (
    need_more,      { block not completed, need more input or more output }
    block_done,     { block flush performed }
    finish_started, { finish started, need only more output at next deflate }
    finish_done);   { finish done, accept no more input or output }

{ Compression function. Returns the block state after the call. }
type
  compress_func = function(var s : deflate_state; flush : TsgInteger) : block_state;

{local}
procedure fill_window(var s : deflate_state); forward;
{local}
function deflate_stored(var s : deflate_state; flush : TsgInteger) : block_state; far; forward;
{local}
function deflate_fast(var s : deflate_state; flush : TsgInteger) : block_state; far; forward;
{local}
function deflate_slow(var s : deflate_state; flush : TsgInteger) : block_state; far; forward;
{local}
procedure lm_init(var s : deflate_state); forward;

{local}
procedure putShortMSB(var s : deflate_state; b : uInt); forward;
{local}
procedure  flush_pending (var strm : z_stream); forward;
{local}
function read_buf(strm : z_streamp;
                  buf : pBytef;
                  size : TsgUnsignedInt) : TsgInteger; forward;
{$ifdef ASMV}
procedure match_init; { asm code initialization }
function longest_match(var deflate_state; cur_match : IPos) : uInt; forward;
{$else}
{local}
function longest_match(var s : deflate_state; cur_match : IPos) : uInt;
  forward;
{$endif}

{$ifdef DEBUG}
{local}
procedure check_match(var s : deflate_state;
                      start, match : IPos;
                      length : TsgInteger); forward;
{$endif}

{  ==========================================================================
  local data }

const
  ZNIL = 0;
{ Tail of hash chains }

const
  TOO_FAR = 4096;
{ Matches of length 3 are discarded if their distance exceeds TOO_FAR }

const
  MIN_LOOKAHEAD = (MAX_MATCH+MIN_MATCH+1);
{ Minimum amount of lookahead, except at the end of the input file.
  See deflate.c for comments about the MIN_MATCH+1. }

{macro MAX_DIST(var s : deflate_state) : uInt;
begin
  MAX_DIST := (s.w_size - MIN_LOOKAHEAD);
end;
  In order to simplify the code, particularly on 16 bit machines, match
  distances are limited to MAX_DIST instead of WSIZE. }


{ Values for max_lazy_match, good_match and max_chain_length, depending on
  the desired pack level (0..9). The values given below have been tuned to
  exclude worst case performance for pathological files. Better values may be
  found for specific files. }

type
  config = record
   good_length : ush; { reduce lazy search above this match length }
   max_lazy : ush;    { do not perform lazy search above this match length }
   nice_length : ush; { quit search above this match length }
   max_chain : ush;
   func : compress_func;
  end;

{local}
const
  configuration_table : array[0..10-1] of config = (
{      good lazy nice chain }
{0} (good_length:0;  max_lazy:0;   nice_length:0;   max_chain:0;    func:deflate_stored),  { store only }
{1} (good_length:4;  max_lazy:4;   nice_length:8;   max_chain:4;    func:deflate_fast), { maximum speed, no lazy matches }
{2} (good_length:4;  max_lazy:5;   nice_length:16;  max_chain:8;    func:deflate_fast),
{3} (good_length:4;  max_lazy:6;   nice_length:32;  max_chain:32;   func:deflate_fast),

{4} (good_length:4;  max_lazy:4;   nice_length:16;  max_chain:16;   func:deflate_slow),  { lazy matches }
{5} (good_length:8;  max_lazy:16;  nice_length:32;  max_chain:32;   func:deflate_slow),
{6} (good_length:8;  max_lazy:16;  nice_length:128; max_chain:128;  func:deflate_slow),
{7} (good_length:8;  max_lazy:32;  nice_length:128; max_chain:256;  func:deflate_slow),
{8} (good_length:32; max_lazy:128; nice_length:258; max_chain:1024; func:deflate_slow),
{9} (good_length:32; max_lazy:258; nice_length:258; max_chain:4096; func:deflate_slow)); { maximum compression }

{ Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
  For deflate_fast() (levels <= 3) good is ignored and lazy has a different
  meaning. }

const
  EQUAL = 0;
{ result of memcmp for equal strings }

{ ==========================================================================
  Update a hash value with the given input byte
  IN  assertion: all calls to to UPDATE_HASH are made with consecutive
     input characters, so that a running hash key can be computed from the
     previous key instead of complete recalculation each time.

macro UPDATE_HASH(s,h,c)
   h := (( (h) shl s^.hash_shift) xor (c)) and s^.hash_mask;
}

{ ===========================================================================
  Insert AnsiString str in the dictionary and set match_head to the previous head
  of the hash chain (the most recent AnsiString with same hash key). Return
  the previous length of the hash chain.
  If this file is compiled with -DFASTEST, the compression level is forced
  to 1, and no hash chains are maintained.
  IN  assertion: all calls to to INSERT_STRING are made with consecutive
     input characters and the first MIN_MATCH bytes of str are valid
     (except for the last MIN_MATCH-1 bytes of the input file). }

procedure INSERT_STRING(var s : deflate_state;
                        str : uInt;
                        var match_head : IPos);
begin
{$ifdef FASTEST}
   {UPDATE_HASH(s, s.ins_h, s.window[(str) + (MIN_MATCH-1)])}
    s.ins_h := ((s.ins_h shl s.hash_shift) xor
                 (s.window^[(str) + (MIN_MATCH-1)])) and s.hash_mask;
    match_head := s.head[s.ins_h]
    s.head[s.ins_h] := Pos(str);
{$else}
   {UPDATE_HASH(s, s.ins_h, s.window[(str) + (MIN_MATCH-1)])}
    s.ins_h := ((s.ins_h shl s.hash_shift) xor
                 (s.window^[(str) + (MIN_MATCH-1)])) and s.hash_mask;

    match_head := s.head^[s.ins_h];
    s.prev^[(str) and s.w_mask] := match_head;
    s.head^[s.ins_h] := Pos(str);
{$endif}
end;

{  =========================================================================
  Initialize the hash table (avoiding 64K overflow for 16 bit systems).
  prev[] will be initialized on the fly.

macro CLEAR_HASH(s)
    s^.head[s^.hash_size-1] := ZNIL;
    zmemzero(pBytef(s^.head), TsgUnsignedInt(s^.hash_size-1)*sizeof(s^.head^[0]));
}

{  ======================================================================== }

function deflateInit2_(var strm : z_stream;
                       level : TsgInteger;
                       method : TsgInteger;
                       windowBits : TsgInteger;
                       memLevel : TsgInteger;
                       strategy : TsgInteger;
                       const version : AnsiString;
                       stream_size : TsgInteger) : TsgInteger;
var
  s : deflate_state_ptr;
  noheader : TsgInteger;

  overlay : pushfArray;
  { We overlay pending_buf and d_buf+l_buf. This works since the average
    output size for (length,distance) codes is <= 24 bits. }
begin
  noheader := 0;
  if (version  =  '') or (version[1] <> ZLIB_VERSION[1]) or
     (stream_size <> sizeof(z_stream)) then
  begin
    deflateInit2_ := Z_VERSION_ERROR;
    exit;
  end;
  {
  if (strm = Z_NULL) then
  begin
    deflateInit2_ := Z_STREAM_ERROR;
    exit;
  end;
  }
  { SetLength(strm.msg, 255); }
  strm.msg := '';
  if not Assigned(strm.zalloc) then
  begin
    {$IFDEF FPC}  strm.zalloc := @zcalloc;  {$ELSE}
    strm.zalloc := zcalloc;
    {$ENDIF}
    strm.opaque := voidpf(0);
  end;
  if not Assigned(strm.zfree) then
    {$IFDEF FPC}  strm.zfree := @zcfree;  {$ELSE}
    strm.zfree := zcfree;
    {$ENDIF}

  if (level  =  Z_DEFAULT_COMPRESSION) then
    level := 6;
{$ifdef FASTEST}
    level := 1;
{$endif}

  if (windowBits < 0) then { undocumented feature: suppress zlib header }
  begin
    noheader := 1;
    windowBits := -windowBits;
  end;
  if (memLevel < 1) or (memLevel > MAX_MEM_LEVEL) or (method <> Z_DEFLATED)
    or (windowBits < 8) or (windowBits > 15) or (level < 0)
    or (level > 9) or (strategy < 0) or (strategy > Z_HUFFMAN_ONLY) then
  begin
    deflateInit2_ := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr (ZALLOC(strm, 1, sizeof(deflate_state)));
  if (s = Z_NULL) then
  begin
    deflateInit2_ := Z_MEM_ERROR;
    exit;
  end;
  strm.state := pInternal_state(s);
  s^.strm := @strm;

  s^.noheader := noheader;
  s^.w_bits := windowBits;
  s^.w_size := 1 shl s^.w_bits;
  s^.w_mask := s^.w_size - 1;

  s^.hash_bits := memLevel + 7;
  s^.hash_size := 1 shl s^.hash_bits;
  s^.hash_mask := s^.hash_size - 1;
  s^.hash_shift :=  ((s^.hash_bits+MIN_MATCH-1) div MIN_MATCH);

  s^.window := pzByteArray (ZALLOC(strm, s^.w_size, 2*sizeof(Byte)));
  s^.prev   := pzPosfArray (ZALLOC(strm, s^.w_size, sizeof(Pos)));
  s^.head   := pzPosfArray (ZALLOC(strm, s^.hash_size, sizeof(Pos)));

  s^.lit_bufsize := 1 shl (memLevel + 6); { 16K elements by default }

  overlay := pushfArray (ZALLOC(strm, s^.lit_bufsize, sizeof(ush)+2));
  s^.pending_buf := pzByteArray (overlay);
  s^.pending_buf_size := ulg(s^.lit_bufsize) * (sizeof(ush)+Long(2));

  if (s^.window = Z_NULL) or (s^.prev = Z_NULL) or (s^.head = Z_NULL)
   or (s^.pending_buf = Z_NULL) then
  begin
    {ERR_MSG(Z_MEM_ERROR);}
    strm.msg := z_errmsg[z_errbase-Z_MEM_ERROR];
    deflateEnd (strm);
    deflateInit2_ := Z_MEM_ERROR;
    exit;
  end;
  s^.d_buf := pushfArray( @overlay^[s^.lit_bufsize div sizeof(ush)] );
  s^.l_buf := puchfArray( @s^.pending_buf^[(1+sizeof(ush))*s^.lit_bufsize] );

  s^.level := level;
  s^.strategy := strategy;
  s^.method := Byte(method);

  deflateInit2_ := deflateReset(strm);
end;

{  ========================================================================= }

function deflateInit2(var strm : z_stream;
                      level : TsgInteger;
                      method : TsgInteger;
                      windowBits : TsgInteger;
                      memLevel : TsgInteger;
                      strategy : TsgInteger) : TsgInteger;
{ a macro }
begin
  deflateInit2 := deflateInit2_(strm, level, method, windowBits,
                   memLevel, strategy, ZLIB_VERSION, sizeof(z_stream));
end;

{  ========================================================================= }

function deflateInit_(strm : z_streamp;
                      level : TsgInteger;
                      const version : AnsiString;
                      stream_size : TsgInteger) : TsgInteger;
begin
  if (strm = Z_NULL) then
    deflateInit_ := Z_STREAM_ERROR
  else
    deflateInit_ := deflateInit2_(strm^, level, Z_DEFLATED, MAX_WBITS,
                   DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY, version, stream_size);
  { To do: ignore strm^.next_in if we use it as window }
end;

{  ========================================================================= }

function deflateInit(var strm : z_stream; level : TsgInteger) : TsgInteger;
{ deflateInit is a macro to allow checking the zlib version
  and the compiler's view of z_stream: }
begin
  deflateInit := deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS,
         DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY, ZLIB_VERSION, sizeof(z_stream));
end;

{  ======================================================================== }
function deflateSetDictionary (var strm : z_stream;
                               dictionary : pBytef;
                               dictLength : uInt) : TsgInteger;
var
  s : deflate_state_ptr;
  length : uInt;
  n : uInt;
  hash_head : IPos;
var
  MAX_DIST : uInt;  {macro}
begin
  length := dictLength;
  hash_head := 0;

  if {(@strm  =  Z_NULL) or}
     (strm.state  =  Z_NULL) or (dictionary  =  Z_NULL)
    or (deflate_state_ptr(strm.state)^.status <> INIT_STATE) then
  begin
    deflateSetDictionary := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr(strm.state);
  strm.adler := adler32(strm.adler, dictionary, dictLength);

  if (length < MIN_MATCH) then
  begin
    deflateSetDictionary := Z_OK;
    exit;
  end;
  MAX_DIST := (s^.w_size - MIN_LOOKAHEAD);
  if (length > MAX_DIST) then
  begin
    length := MAX_DIST;
{$ifndef USE_DICT_HEAD}
    Inc(dictionary, dictLength - length);  { use the tail of the dictionary }
{$endif}
  end;

  zmemcpy( pBytef(s^.window), dictionary, length);
  s^.strstart := length;
  s^.block_start := long(length);

  { Insert all strings in the hash table (except for the last two bytes).
    s^.lookahead stays null, so s^.ins_h will be recomputed at the next
    call of fill_window. }

  s^.ins_h := s^.window^[0];
  {UPDATE_HASH(s, s^.ins_h, s^.window[1]);}
  s^.ins_h := ((s^.ins_h shl s^.hash_shift) xor (s^.window^[1]))
              and s^.hash_mask;

  for n := 0 to length - MIN_MATCH do
  begin
    INSERT_STRING(s^, n, hash_head);
  end;
  {if (hash_head <> 0) then
    hash_head := 0;  - to make compiler happy }
  deflateSetDictionary := Z_OK;
end;

{  ======================================================================== }
function deflateReset (var strm : z_stream) : TsgInteger;
var
  s : deflate_state_ptr;
begin
  if {(@strm = Z_NULL) or}
   (strm.state = Z_NULL)
   or (not Assigned(strm.zalloc)) or (not Assigned(strm.zfree)) then
  begin
    deflateReset := Z_STREAM_ERROR;
    exit;
  end;

  strm.total_out := 0;
  strm.total_in := 0;
  strm.msg := '';      { use zfree if we ever allocate msg dynamically }
  strm.data_type := Z_UNKNOWN;

  s := deflate_state_ptr(strm.state);
  s^.pending := 0;
  s^.pending_out := pBytef(s^.pending_buf);

  if (s^.noheader < 0) then
  begin
    s^.noheader := 0; { was set to -1 by deflate(..., Z_FINISH); }
  end;
  if s^.noheader <> 0 then
    s^.status := BUSY_STATE
  else
    s^.status := INIT_STATE;
  strm.adler := 1;
  s^.last_flush := Z_NO_FLUSH;

  _tr_init(s^);
  lm_init(s^);

  deflateReset := Z_OK;
end;

{  ======================================================================== }
function deflateParams(var strm : z_stream;
                       level : TsgInteger;
                       strategy : TsgInteger) : TsgInteger;
var
  s : deflate_state_ptr;
  func : compress_func;
  err : TsgInteger;
begin
  err := Z_OK;
  if {(@strm  =  Z_NULL) or} (strm.state  =  Z_NULL) then
  begin
    deflateParams := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr(strm.state);

  if (level = Z_DEFAULT_COMPRESSION) then
  begin
    level := 6;
  end;
  if (level < 0) or (level > 9) or (strategy < 0)
  or (strategy > Z_HUFFMAN_ONLY) then
  begin
    deflateParams := Z_STREAM_ERROR;
    exit;
  end;
  func := configuration_table[s^.level].func;

  if (@func <> @configuration_table[level].func)
    and (strm.total_in <> 0) then
  begin
      { Flush the last buffer: }
      err := deflate(strm, Z_PARTIAL_FLUSH);
  end;
  if (s^.level <> level) then
  begin
    s^.level := level;
    s^.max_lazy_match   := configuration_table[level].max_lazy;
    s^.good_match       := configuration_table[level].good_length;
    s^.nice_match       := configuration_table[level].nice_length;
    s^.max_chain_length := configuration_table[level].max_chain;
  end;
  s^.strategy := strategy;
  deflateParams := err;
end;

{ =========================================================================
  Put a short in the pending buffer. The 16-bit value is put in MSB order.
  IN assertion: the stream state is correct and there is enough room in
  pending_buf. }

{local}
procedure putShortMSB (var s : deflate_state; b : uInt);
begin
  s.pending_buf^[s.pending] := Byte(b shr 8);
  Inc(s.pending);
  s.pending_buf^[s.pending] := Byte(b and $ff);
  Inc(s.pending);
end;

{ =========================================================================
  Flush as much pending output as possible. All deflate() output goes
  through this function so some applications may wish to modify it
  to avoid allocating a large strm^.next_out buffer and copying into it.
  (See also read_buf()). }

{local}
procedure flush_pending(var strm : z_stream);
var
  len : TsgUnsignedInt;
  s : deflate_state_ptr;
begin
  s := deflate_state_ptr(strm.state);
  len := s^.pending;

  if (len > strm.avail_out) then
    len := strm.avail_out;
  if (len = 0) then
    exit;

  zmemcpy(strm.next_out, s^.pending_out, len);
  Inc(strm.next_out, len);
  Inc(s^.pending_out, len);
  Inc(strm.total_out, len);
  Dec(strm.avail_out, len);
  Dec(s^.pending, len);
  if (s^.pending = 0) then
  begin
    s^.pending_out := pBytef(s^.pending_buf);
  end;
end;

{ ========================================================================= }
function deflate (var strm : z_stream; flush : TsgInteger) : TsgInteger;
var
  old_flush : TsgInteger; { value of flush param for previous deflate call }
  s : deflate_state_ptr;
var
  header : uInt;
  level_flags : uInt;
var
  bstate : block_state;
begin
  if {(@strm = Z_NULL) or} (strm.state = Z_NULL)
    or (flush > Z_FINISH) or (flush < 0) then
  begin
    deflate := Z_STREAM_ERROR;
    exit;
  end;
  s := deflate_state_ptr(strm.state);

  if (strm.next_out = Z_NULL) or
     ((strm.next_in = Z_NULL) and (strm.avail_in <> 0)) or
     ((s^.status = FINISH_STATE) and (flush <> Z_FINISH)) then
  begin
    {ERR_RETURN(strm^, Z_STREAM_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_STREAM_ERROR];
    deflate := Z_STREAM_ERROR;
    exit;
  end;
  if (strm.avail_out = 0) then
  begin
    {ERR_RETURN(strm^, Z_BUF_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
    deflate := Z_BUF_ERROR;
    exit;
  end;

  s^.strm := @strm; { just in case }
  old_flush := s^.last_flush;
  s^.last_flush := flush;

  { Write the zlib header }
  if (s^.status = INIT_STATE) then
  begin

    header := (Z_DEFLATED + ((s^.w_bits-8) shl 4)) shl 8;
    level_flags := (s^.level-1) shr 1;

    if (level_flags > 3) then
      level_flags := 3;
    header := header or (level_flags shl 6);
    if (s^.strstart <> 0) then
      header := header or PRESET_DICT;
    Inc(header, 31 - (header mod 31));

    s^.status := BUSY_STATE;
    putShortMSB(s^, header);

    { Save the adler32 of the preset dictionary: }
    if (s^.strstart <> 0) then
    begin
      putShortMSB(s^, uInt(strm.adler shr 16));
      putShortMSB(s^, uInt(strm.adler and $ffff));
    end;
    strm.adler := long(1);
  end;

  { Flush as much pending output as possible }
  if (s^.pending <> 0) then
  begin
    flush_pending(strm);
    if (strm.avail_out = 0) then
    begin
      { Since avail_out is 0, deflate will be called again with
	more output space, but possibly with both pending and
	avail_in equal to zero. There won't be anything to do,
	but this is not an error situation so make sure we
	return OK instead of BUF_ERROR at next call of deflate: }

      s^.last_flush := -1;
      deflate := Z_OK;
      exit;
    end;

  { Make sure there is something to do and avoid duplicate consecutive
    flushes. For repeated and useless calls with Z_FINISH, we keep
    returning Z_STREAM_END instead of Z_BUFF_ERROR. }

  end
  else
    if (strm.avail_in = 0) and (flush <= old_flush)
      and (flush <> Z_FINISH) then
    begin
      {ERR_RETURN(strm^, Z_BUF_ERROR);}
      strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
      deflate := Z_BUF_ERROR;
      exit;
    end;

  { User must not provide more input after the first FINISH: }
  if (s^.status = FINISH_STATE) and (strm.avail_in <> 0) then
  begin
    {ERR_RETURN(strm^, Z_BUF_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
    deflate := Z_BUF_ERROR;
    exit;
  end;

  { Start a new block or continue the current one. }
  if (strm.avail_in <> 0) or (s^.lookahead <> 0)
    or ((flush <> Z_NO_FLUSH) and (s^.status <> FINISH_STATE)) then
  begin
    bstate := configuration_table[s^.level].func(s^, flush);

    if (bstate = finish_started) or (bstate = finish_done) then
      s^.status := FINISH_STATE;

    if (bstate = need_more) or (bstate = finish_started) then
    begin
      if (strm.avail_out = 0) then
        s^.last_flush := -1; { avoid BUF_ERROR next call, see above }

      deflate := Z_OK;
      exit;
      { If flush != Z_NO_FLUSH && avail_out == 0, the next call
	of deflate should use the same flush parameter to make sure
	that the flush is complete. So we don't have to output an
	empty block here, this will be done at next call. This also
	ensures that for a very small output buffer, we emit at most
	 one empty block. }
    end;
    if (bstate = block_done) then
    begin
      if (flush = Z_PARTIAL_FLUSH) then
        _tr_align(s^)
      else
      begin  { FULL_FLUSH or SYNC_FLUSH }
        _tr_stored_block(s^, pcharf(NIL), Long(0), FALSE);
        { For a full flush, this empty block will be recognized
          as a special marker by inflate_sync(). }

        if (flush = Z_FULL_FLUSH) then
        begin
          {macro CLEAR_HASH(s);}             { forget history }
          s^.head^[s^.hash_size-1] := ZNIL;
          zmemzero(pBytef(s^.head), TsgUnsignedInt(s^.hash_size-1)*sizeof(s^.head^[0]));
        end;
      end;

      flush_pending(strm);
      if (strm.avail_out = 0) then
      begin
        s^.last_flush := -1; { avoid BUF_ERROR at next call, see above }
	deflate := Z_OK;
        exit;
      end;

    end;
  end;
  {$IFDEF DEBUG}
  Assert(strm.avail_out > 0, 'bug2');
  {$ENDIF}
  if (flush <> Z_FINISH) then
  begin
    deflate := Z_OK;
    exit;
  end;

  if (s^.noheader <> 0) then
  begin
    deflate := Z_STREAM_END;
    exit;
  end;

  { Write the zlib trailer (adler32) }
  putShortMSB(s^, uInt(strm.adler shr 16));
  putShortMSB(s^, uInt(strm.adler and $ffff));
  flush_pending(strm);
  { If avail_out is zero, the application will call deflate again
    to flush the rest. }

  s^.noheader := -1; { write the trailer only once! }
  if s^.pending <> 0 then
    deflate := Z_OK
  else
    deflate := Z_STREAM_END;
end;

{ ========================================================================= }
function deflateEnd (var strm : z_stream) : TsgInteger;
var
  status : TsgInteger;
  s : deflate_state_ptr;
begin
  if {(@strm = Z_NULL) or} (strm.state = Z_NULL) then
  begin
    deflateEnd := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr(strm.state);
  status := s^.status;
  if (status <> INIT_STATE) and (status <> BUSY_STATE) and
     (status <> FINISH_STATE) then
  begin
    deflateEnd := Z_STREAM_ERROR;
    exit;
  end;

  { Deallocate in reverse order of allocations: }
  TRY_FREE(strm, s^.pending_buf);
  TRY_FREE(strm, s^.head);
  TRY_FREE(strm, s^.prev);
  TRY_FREE(strm, s^.window);

  ZFREE(strm, s);
  strm.state := Z_NULL;

  if status = BUSY_STATE then
    deflateEnd := Z_DATA_ERROR
  else
    deflateEnd := Z_OK;
end;

{ =========================================================================
  Copy the source state to the destination state.
  To simplify the source, this is not supported for 16-bit MSDOS (which
  doesn't have enough memory anyway to duplicate compression states). }


{ ========================================================================= }
function deflateCopy (dest, source : z_streamp) : TsgInteger;
{$ifndef MAXSEG_64K}
var
  ds : deflate_state_ptr;
  ss : deflate_state_ptr;
  overlay : pushfArray;
{$endif}
begin
{$ifdef MAXSEG_64K}
  deflateCopy := Z_STREAM_ERROR;
  exit;
{$else}

  if (source = Z_NULL) or (dest = Z_NULL) or (source^.state = Z_NULL) then
  begin
    deflateCopy := Z_STREAM_ERROR;
    exit;
  end;
  ss := deflate_state_ptr(source^.state);
  dest^ := source^;

  ds := deflate_state_ptr( ZALLOC(dest^, 1, sizeof(deflate_state)) );
  if (ds = Z_NULL) then
  begin
    deflateCopy := Z_MEM_ERROR;
    exit;
  end;
  dest^.state := pInternal_state(ds);
  ds^ := ss^;
  ds^.strm := dest;

  ds^.window := pzByteArray ( ZALLOC(dest^, ds^.w_size, 2*sizeof(Byte)) );
  ds^.prev   := pzPosfArray ( ZALLOC(dest^, ds^.w_size, sizeof(Pos)) );
  ds^.head   := pzPosfArray ( ZALLOC(dest^, ds^.hash_size, sizeof(Pos)) );
  overlay := pushfArray ( ZALLOC(dest^, ds^.lit_bufsize, sizeof(ush)+2) );
  ds^.pending_buf := pzByteArray ( overlay );

  if (ds^.window = Z_NULL) or (ds^.prev = Z_NULL) or (ds^.head = Z_NULL)
     or (ds^.pending_buf = Z_NULL) then
  begin
    deflateEnd (dest^);
    deflateCopy := Z_MEM_ERROR;
    exit;
  end;
  { following zmemcpy do not work for 16-bit MSDOS }
  zmemcpy(pBytef(ds^.window), pBytef(ss^.window), ds^.w_size * 2 * sizeof(Byte));
  zmemcpy(pBytef(ds^.prev), pBytef(ss^.prev), ds^.w_size * sizeof(Pos));
  zmemcpy(pBytef(ds^.head), pBytef(ss^.head), ds^.hash_size * sizeof(Pos));
  zmemcpy(pBytef(ds^.pending_buf), pBytef(ss^.pending_buf), uInt(ds^.pending_buf_size));

  ds^.pending_out := @ds^.pending_buf^[ptr2int(ss^.pending_out) - ptr2int(ss^.pending_buf)];
  ds^.d_buf := pushfArray (@overlay^[ds^.lit_bufsize div sizeof(ush)] );
  ds^.l_buf := puchfArray (@ds^.pending_buf^[(1+sizeof(ush))*ds^.lit_bufsize]);

  ds^.l_desc.dyn_tree := tree_ptr(@ds^.dyn_ltree);
  ds^.d_desc.dyn_tree := tree_ptr(@ds^.dyn_dtree);
  ds^.bl_desc.dyn_tree := tree_ptr(@ds^.bl_tree);

  deflateCopy := Z_OK;
{$endif}
end;


{ ===========================================================================
  Read a new buffer from the current input stream, update the adler32
  and total number of bytes read.  All deflate() input goes through
  this function so some applications may wish to modify it to avoid
  allocating a large strm^.next_in buffer and copying from it.
  (See also flush_pending()). }

{local}
function read_buf(strm : z_streamp; buf : pBytef; size : TsgUnsignedInt) : TsgInteger;
var
  len : TsgUnsignedInt;
begin
  len := strm^.avail_in;

  if (len > size) then
    len := size;
  if (len = 0) then
  begin
    read_buf := 0;
    exit;
  end;

  Dec(strm^.avail_in, len);

  if deflate_state_ptr(strm^.state)^.noheader = 0 then
  begin
    strm^.adler := adler32(strm^.adler, strm^.next_in, len);
  end;
  zmemcpy(buf, strm^.next_in, len);
  Inc(strm^.next_in, len);
  Inc(strm^.total_in, len);

  read_buf := TsgInteger(len);
end;

{ ===========================================================================
  Initialize the "longest match" routines for a new zlib stream }

{local}
procedure lm_init (var s : deflate_state);
begin
  s.window_size := ulg( uLong(2)*s.w_size);

  {macro CLEAR_HASH(s);}
  s.head^[s.hash_size-1] := ZNIL;
  zmemzero(pBytef(s.head), TsgUnsignedInt(s.hash_size-1)*sizeof(s.head^[0]));

  { Set the default configuration parameters: }

  s.max_lazy_match   := configuration_table[s.level].max_lazy;
  s.good_match       := configuration_table[s.level].good_length;
  s.nice_match       := configuration_table[s.level].nice_length;
  s.max_chain_length := configuration_table[s.level].max_chain;

  s.strstart := 0;
  s.block_start := long(0);
  s.lookahead := 0;
  s.prev_length := MIN_MATCH-1;
  s.match_length := MIN_MATCH-1;
  s.match_available := FALSE;
  s.ins_h := 0;
{$ifdef ASMV}
  match_init; { initialize the asm code }
{$endif}
end;

{ ===========================================================================
  Set match_start to the longest match starting at the given AnsiString and
  return its length. Matches shorter or equal to prev_length are discarded,
  in which case the result is equal to prev_length and match_start is
  garbage.
  IN assertions: cur_match is the head of the hash chain for the current
    AnsiString (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
  OUT assertion: the match length is not greater than s^.lookahead. }


{$ifndef ASMV}
{ For 80x86 and 680x0, an optimized version will be provided in match.asm or
  match.S. The code will be functionally equivalent. }

{$ifndef FASTEST}

{local}
function longest_match(var s : deflate_state;
                       cur_match : IPos  { current match }
                       ) : uInt;
label
  nextstep;
var
  chain_length : TsgUnsignedInt;    { max hash chain length }
  {register} scan : pBytef;   { current AnsiString }
  {register} match : pBytef;  { matched AnsiString }
  {register} len : TsgInteger;       { length of current match }
  best_len : TsgInteger;             { best match length so far }
  nice_match : TsgInteger;           { stop if match long enough }
  limit : IPos;

  prev : pzPosfArray;
  wmask : uInt;
{$ifdef UNALIGNED_OK}
  {register} strend : pBytef;
  {register} scan_start : ush;
  {register} scan_end : ush;
{$else}
  {register} strend : pBytef;
  {register} scan_end1 : Byte;
  {register} scan_end : Byte;
{$endif}
var
  MAX_DIST : uInt;
begin
  chain_length := s.max_chain_length; { max hash chain length }
  scan := @(s.window^[s.strstart]);
  best_len := s.prev_length;              { best match length so far }
  nice_match := s.nice_match;             { stop if match long enough }


  MAX_DIST := s.w_size - MIN_LOOKAHEAD;
{In order to simplify the code, particularly on 16 bit machines, match
distances are limited to MAX_DIST instead of WSIZE. }

  if s.strstart > IPos(MAX_DIST) then
    limit := s.strstart - IPos(MAX_DIST)
  else
    limit := ZNIL;
  { Stop when cur_match becomes <= limit. To simplify the code,
    we prevent matches with the AnsiString of window index 0. }

  prev := s.prev;
  wmask := s.w_mask;

{$ifdef UNALIGNED_OK}
  { Compare two bytes at a time. Note: this is not always beneficial.
    Try with and without -DUNALIGNED_OK to check. }

  strend := pBytef(@(s.window^[s.strstart + MAX_MATCH - 1]));
  scan_start := pushf(scan)^;
  scan_end   := pushfArray(scan)^[best_len-1];   { fix }
{$else}
  strend := pBytef(@(s.window^[s.strstart + MAX_MATCH]));
  {$IFOPT R+} {$R-} {$DEFINE NoRangeCheck} {$ENDIF}
  scan_end1  := pzByteArray(scan)^[best_len-1];
  {$IFDEF NoRangeCheck} {$R+} {$UNDEF NoRangeCheck} {$ENDIF}
  scan_end   := pzByteArray(scan)^[best_len];
{$endif}

    { The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
      It is easy to get rid of this optimization if necessary. }
    {$IFDEF DEBUG}
    Assert((s.hash_bits >= 8) and (MAX_MATCH = 258), 'Code too clever');
    {$ENDIF}
    { Do not waste too much time if we already have a good match: }
    if (s.prev_length >= s.good_match) then
    begin
      chain_length := chain_length shr 2;
    end;

    { Do not look for matches beyond the end of the input. This is necessary
      to make deflate deterministic. }

    if (uInt(nice_match) > s.lookahead) then
      nice_match := s.lookahead;
    {$IFDEF DEBUG}
    Assert(ulg(s.strstart) <= s.window_size-MIN_LOOKAHEAD, 'need lookahead');
    {$ENDIF}
    repeat
        {$IFDEF DEBUG}
        Assert(cur_match < s.strstart, 'no future');
        {$ENDIF}
        match := @(s.window^[cur_match]);

        { Skip to next match if the match length cannot increase
          or if the match length is less than 2: }

{$undef DO_UNALIGNED_OK}
{$ifdef UNALIGNED_OK}
  {$ifdef MAX_MATCH_IS_258}
    {$define DO_UNALIGNED_OK}
  {$endif}
{$endif}

{$ifdef DO_UNALIGNED_OK}
        { This code assumes sizeof(unsigned short) = 2. Do not use
          UNALIGNED_OK if your compiler uses a different size. }
  {$IFOPT R+} {$R-} {$DEFINE NoRangeCheck} {$ENDIF}
        if (pushfArray(match)^[best_len-1] <> scan_end) or
           (pushf(match)^ <> scan_start) then
          goto nextstep; {continue;}
  {$IFDEF NoRangeCheck} {$R+} {$UNDEF NoRangeCheck} {$ENDIF}

        { It is not necessary to compare scan[2] and match[2] since they are
          always equal when the other bytes match, given that the hash keys
          are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
          strstart+3, +5, ... up to strstart+257. We check for insufficient
          lookahead only every 4th comparison; the 128th check will be made
          at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
          necessary to put more guard bytes at the end of the window, or
          to check more often for insufficient lookahead. }
        {$IFDEF DEBUG}
        Assert(pzByteArray(scan)^[2] = pzByteArray(match)^[2], 'scan[2]?');
        {$ENDIF}
        Inc(scan);
        Inc(match);

        repeat
          Inc(scan,2); Inc(match,2); if (pushf(scan)^<>pushf(match)^) then break;
          Inc(scan,2); Inc(match,2); if (pushf(scan)^<>pushf(match)^) then break;
          Inc(scan,2); Inc(match,2); if (pushf(scan)^<>pushf(match)^) then break;
          Inc(scan,2); Inc(match,2); if (pushf(scan)^<>pushf(match)^) then break;
        until (ptr2int(scan) >= ptr2int(strend));
        { The funny "do while" generates better code on most compilers }

        { Here, scan <= window+strstart+257 }
        {$IFDEF DEBUG}
        {$ifopt R+} {$define RangeCheck} {$endif} {$R-}
        Assert(ptr2int(scan) <=
               ptr2int(@(s.window^[TsgUnsignedInt(s.window_size-1)])),
               'wild scan');
        {$ifdef RangeCheck} {$R+} {$undef RangeCheck} {$endif}
        {$ENDIF}
        if (scan^ = match^) then
          Inc(scan);

        len := (MAX_MATCH - 1) - TsgInteger(ptr2int(strend)) + TsgInteger(ptr2int(scan));
        scan := strend;
        Dec(scan, (MAX_MATCH-1));

{$else} { UNALIGNED_OK }

  {$IFOPT R+} {$R-} {$DEFINE NoRangeCheck} {$ENDIF}
        if (pzByteArray(match)^[best_len]   <> scan_end) or
           (pzByteArray(match)^[best_len-1] <> scan_end1) or
           (match^ <> scan^) then
          goto nextstep; {continue;}
  {$IFDEF NoRangeCheck} {$R+} {$UNDEF NoRangeCheck} {$ENDIF}
        Inc(match);
        if (match^ <> pzByteArray(scan)^[1]) then
          goto nextstep; {continue;}

        { The check at best_len-1 can be removed because it will be made
          again later. (This heuristic is not always a win.)
          It is not necessary to compare scan[2] and match[2] since they
          are always equal when the other bytes match, given that
          the hash keys are equal and that HASH_BITS >= 8. }

        Inc(scan, 2);
        Inc(match);
        {$IFDEF DEBUG}
        Assert( scan^ = match^, 'match[2]?');
        {$ENDIF}
        { We check for insufficient lookahead only every 8th comparison;
          the 256th check will be made at strstart+258. }

        repeat
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
          Inc(scan); Inc(match); if (scan^ <> match^) then break;
        until (ptr2int(scan) >= ptr2int(strend));

        {$IFDEF DEBUG}
        Assert(ptr2int(scan) <=
               ptr2int(@(s.window^[TsgUnsignedInt(s.window_size-1)])),
               'wild scan');
        {$ENDIF}

        len := MAX_MATCH - TsgInteger(ptr2int(strend) - ptr2int(scan));
        scan := strend;
        Dec(scan, MAX_MATCH);

{$endif} { UNALIGNED_OK }

        if (len > best_len) then
        begin
            s.match_start := cur_match;
            best_len := len;
            if (len >= nice_match) then
              break;
  {$IFOPT R+} {$R-} {$DEFINE NoRangeCheck} {$ENDIF}
{$ifdef UNALIGNED_OK}
            scan_end   := pzByteArray(scan)^[best_len-1];
{$else}
            scan_end1  := pzByteArray(scan)^[best_len-1];
            scan_end   := pzByteArray(scan)^[best_len];
{$endif}
  {$IFDEF NoRangeCheck} {$R+} {$UNDEF NoRangeCheck} {$ENDIF}
        end;
    nextstep:
      cur_match := prev^[cur_match and wmask];
      Dec(chain_length);
    until (cur_match <= limit) or (chain_length = 0);

    if (uInt(best_len) <= s.lookahead) then
      longest_match := uInt(best_len)
    else
      longest_match := s.lookahead;
end;
{$endif} { ASMV }

{$else} { FASTEST }
{ ---------------------------------------------------------------------------
  Optimized version for level = 1 only }

{local}
function longest_match(var s : deflate_state;
                       cur_match : IPos  { current match }
                       ) : uInt;
var
  {register} scan : pBytef;   { current AnsiString }
  {register} match : pBytef;  { matched AnsiString }
  {register} len : TsgInteger;       { length of current match }
  {register} strend : pBytef;
begin
  scan := @s.window^[s.strstart];
  strend := @s.window^[s.strstart + MAX_MATCH];


    { The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
      It is easy to get rid of this optimization if necessary. }
    {$IFDEF DEBUG}
    Assert((s.hash_bits >= 8) and (MAX_MATCH = 258), 'Code too clever');

    Assert(ulg(s.strstart) <= s.window_size-MIN_LOOKAHEAD, 'need lookahead');

    Assert(cur_match < s.strstart, 'no future');
    {$ENDIF}
    match := s.window + cur_match;

    { Return failure if the match length is less than 2: }

    if (match[0] <> scan[0]) or (match[1] <> scan[1]) then
    begin
      longest_match := MIN_MATCH-1;
      exit;
    end;

    { The check at best_len-1 can be removed because it will be made
      again later. (This heuristic is not always a win.)
      It is not necessary to compare scan[2] and match[2] since they
      are always equal when the other bytes match, given that
      the hash keys are equal and that HASH_BITS >= 8. }

    scan += 2, match += 2;
    Assert(scan^ = match^, 'match[2]?');

    { We check for insufficient lookahead only every 8th comparison;
      the 256th check will be made at strstart+258. }

    repeat
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
      Inc(scan); Inc(match); if scan^<>match^ then break;
    until (ptr2int(scan) >= ptr2int(strend));

    Assert(scan <= s.window+TsgUnsignedInt(s.window_size-1), 'wild scan');

    len := MAX_MATCH - TsgInteger(strend - scan);

    if (len < MIN_MATCH) then
    begin
      return := MIN_MATCH - 1;
      exit;
    end;

    s.match_start := cur_match;
    if len <= s.lookahead then
      longest_match := len
    else
      longest_match := s.lookahead;
end;
{$endif} { FASTEST }

{$ifdef DEBUG}
{ ===========================================================================
  Check that the match at match_start is indeed a match. }

{local}
procedure check_match(var s : deflate_state;
                      start, match : IPos;
                      length : TsgInteger);
begin
  exit;
  { check that the match is indeed a match }
  if (zmemcmp(pBytef(@s.window^[match]),
              pBytef(@s.window^[start]), length) <> EQUAL) then
  begin
    WriteLn(' start ',start,', match ',match ,' length ', length);
    repeat
      Write(AnsiChar(s.window^[match]), AnsiChar(s.window^[start]));
      Inc(match);
      Inc(start);
      Dec(length);
    Until (length = 0);
    z_error('invalid match');
  end;
  if (z_verbose > 1) then
  begin
    Write('\\[',start-match,',',length,']');
    repeat
       Write(AnsiChar(s.window^[start]));
       Inc(start);
       Dec(length);
    Until (length = 0);
  end;
end;
{$endif}

{ ===========================================================================
  Fill the window when the lookahead becomes insufficient.
  Updates strstart and lookahead.

  IN assertion: lookahead < MIN_LOOKAHEAD
  OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
     At least one byte has been read, or avail_in = 0; reads are
     performed for at least two bytes (required for the zip translate_eol
     option -- not supported here). }

{local}
procedure fill_window(var s : deflate_state);
var
  {register} n, m : TsgUnsignedInt;
  {register} p : pPosf;
  more : TsgUnsignedInt;    { Amount of free space at the end of the window. }
  wsize : uInt;
begin
   wsize := s.w_size;
   repeat
     more := TsgUnsignedInt(s.window_size -ulg(s.lookahead) -ulg(s.strstart));

     { Deal with !@#$% 64K limit: }
     if (more = 0) and (s.strstart = 0) and (s.lookahead = 0) then
       more := wsize
     else
     if (more = TsgUnsignedInt(-1)) then
     begin
       { Very unlikely, but possible on 16 bit machine if strstart = 0
         and lookahead = 1 (input done one byte at time) }
       Dec(more);

       { If the window is almost full and there is insufficient lookahead,
         move the upper half to the lower one to make room in the upper half.}
     end
     else
       if (s.strstart >= wsize+ {MAX_DIST}(wsize-MIN_LOOKAHEAD)) then
       begin
         zmemcpy( pBytef(s.window), pBytef(@(s.window^[wsize])),
                 TsgUnsignedInt(wsize));
         Dec(s.match_start, wsize);
         Dec(s.strstart, wsize); { we now have strstart >= MAX_DIST }
         Dec(s.block_start, long(wsize));

         { Slide the hash table (could be avoided with 32 bit values
           at the expense of memory usage). We slide even when level = 0
           to keep the hash table consistent if we switch back to level > 0
           later. (Using level 0 permanently is not an optimal usage of
           zlib, so we don't care about this pathological case.) }

         n := s.hash_size;
         p := @s.head^[n];
         repeat
           Dec(p);
           m := p^;
           if (m >= wsize) then
             p^ := Pos(m-wsize)
           else
             p^ := Pos(ZNIL);
           Dec(n);
         Until (n=0);

         n := wsize;
{$ifndef FASTEST}
         p := @s.prev^[n];
         repeat
           Dec(p);
           m := p^;
           if (m >= wsize) then
             p^ := Pos(m-wsize)
           else
             p^:= Pos(ZNIL);
             { If n is not on any hash chain, prev^[n] is garbage but
               its value will never be used. }
           Dec(n);
         Until (n=0);
{$endif}
         Inc(more, wsize);
     end;
     if (s.strm^.avail_in = 0) then
       exit;

     {* If there was no sliding:
      *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
      *    more == window_size - lookahead - strstart
      * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
      * => more >= window_size - 2*WSIZE + 2
      * In the BIG_MEM or MMAP case (not yet supported),
      *   window_size == input_size + MIN_LOOKAHEAD  &&
      *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
      * Otherwise, window_size == 2*WSIZE so more >= 2.
      * If there was sliding, more >= WSIZE. So in all cases, more >= 2. }

     {$IFDEF DEBUG}
     Assert(more >= 2, 'more < 2');
     {$ENDIF}

     n := read_buf(s.strm, pBytef(@(s.window^[s.strstart + s.lookahead])),
                  more);
     Inc(s.lookahead, n);

     { Initialize the hash value now that we have some input: }
     if (s.lookahead >= MIN_MATCH) then
     begin
       s.ins_h := s.window^[s.strstart];
       {UPDATE_HASH(s, s.ins_h, s.window[s.strstart+1]);}
       s.ins_h := ((s.ins_h shl s.hash_shift) xor s.window^[s.strstart+1])
                     and s.hash_mask;
{$ifdef MIN_MATCH <> 3}
       Call UPDATE_HASH() MIN_MATCH-3 more times
{$endif}
     end;
     { If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
       but this is not important since only literal bytes will be emitted. }

   until (s.lookahead >= MIN_LOOKAHEAD) or (s.strm^.avail_in = 0);
end;

{ ===========================================================================
  Flush the current block, with given end-of-file flag.
  IN assertion: strstart is set to the end of the current match. }

procedure FLUSH_BLOCK_ONLY(var s : deflate_state; eof : boolean); {macro}
begin
  if (s.block_start >= Long(0)) then
    _tr_flush_block(s, pcharf(@s.window^[TsgUnsignedInt(s.block_start)]),
                    ulg(long(s.strstart) - s.block_start), eof)
  else
    _tr_flush_block(s, pcharf(Z_NULL),
                    ulg(long(s.strstart) - s.block_start), eof);

  s.block_start := s.strstart;
  flush_pending(s.strm^);
  {$IFDEF DEBUG}
  Tracev('[FLUSH]');
  {$ENDIF}
end;

{ Same but force premature exit if necessary.
macro FLUSH_BLOCK(var s : deflate_state; eof : boolean) : boolean;
var
  result : block_state;
begin
 FLUSH_BLOCK_ONLY(s, eof);
 if (s.strm^.avail_out = 0) then
 begin
   if eof then
     result := finish_started
   else
     result := need_more;
   exit;
 end;
end;
}

{ ===========================================================================
  Copy without compression as much as possible from the input stream, return
  the current block state.
  This function does not insert new strings in the dictionary since
  uncompressible data is probably not useful. This function is used
  only for the level=0 compression option.
  NOTE: this function should be optimized to avoid extra copying from
  window to pending_buf. }


{local}
function deflate_stored(var s : deflate_state; flush : TsgInteger) : block_state;
{ Stored blocks are limited to 0xffff bytes, pending_buf is limited
  to pending_buf_size, and each stored block has a 5 byte header: }
var
  max_block_size : ulg;
  max_start : ulg;
begin
  max_block_size := $ffff;
  if (max_block_size > s.pending_buf_size - 5) then
    max_block_size := s.pending_buf_size - 5;

  { Copy as much as possible from input to output: }
  while TRUE do
  begin
    { Fill the window as much as possible: }
    if (s.lookahead <= 1) then
    begin
      {$IFDEF DEBUG}
      Assert( (s.strstart < s.w_size + {MAX_DIST}s.w_size-MIN_LOOKAHEAD) or
              (s.block_start >= long(s.w_size)), 'slide too late');
      {$ENDIF}
      fill_window(s);
      if (s.lookahead = 0) and (flush = Z_NO_FLUSH) then
      begin
        deflate_stored := need_more;
        exit;
      end;

      if (s.lookahead = 0) then
        break; { flush the current block }
    end;
    {$IFDEF DEBUG}
    Assert(s.block_start >= long(0), 'block gone');
    {$ENDIF}
    Inc(s.strstart, s.lookahead);
    s.lookahead := 0;

    { Emit a stored block if pending_buf will be full: }
    max_start := s.block_start + max_block_size;
    if (s.strstart = 0) or (ulg(s.strstart) >= max_start) then
    begin
      { strstart = 0 is possible when wraparound on 16-bit machine }
      s.lookahead := uInt(s.strstart - max_start);
      s.strstart := uInt(max_start);
      {FLUSH_BLOCK(s, FALSE);}
      FLUSH_BLOCK_ONLY(s, FALSE);
      if (s.strm^.avail_out = 0) then
      begin
        deflate_stored := need_more;
        exit;
      end;
    end;

    { Flush if we may have to slide, otherwise block_start may become
      negative and the data will be gone: }

    if (s.strstart - uInt(s.block_start) >= {MAX_DIST}
        s.w_size-MIN_LOOKAHEAD) then
    begin
      {FLUSH_BLOCK(s, FALSE);}
      FLUSH_BLOCK_ONLY(s, FALSE);
      if (s.strm^.avail_out = 0) then
      begin
        deflate_stored := need_more;
        exit;
      end;
    end;
  end;

  {FLUSH_BLOCK(s, flush = Z_FINISH);}
  FLUSH_BLOCK_ONLY(s, flush = Z_FINISH);
  if (s.strm^.avail_out = 0) then
  begin
    if flush = Z_FINISH then
      deflate_stored := finish_started
    else
      deflate_stored := need_more;
    exit;
  end;

  if flush = Z_FINISH then
    deflate_stored := finish_done
  else
    deflate_stored := block_done;
end;

{ ===========================================================================
  Compress as much as possible from the input stream, return the current
  block state.
  This function does not perform lazy evaluation of matches and inserts
  new strings in the dictionary only for unmatched strings or for short
  matches. It is used only for the fast compression options. }

{local}
function deflate_fast(var s : deflate_state; flush : TsgInteger) : block_state;
var
  hash_head : IPos;     { head of the hash chain }
  bflush : boolean;     { set if current block must be flushed }
begin
  hash_head := ZNIL;
  while TRUE do
  begin
  { Make sure that we always have enough lookahead, except
    at the end of the input file. We need MAX_MATCH bytes
    for the next match, plus MIN_MATCH bytes to insert the
    AnsiString following the next match. }

    if (s.lookahead < MIN_LOOKAHEAD) then
    begin
      fill_window(s);
      if (s.lookahead < MIN_LOOKAHEAD) and (flush = Z_NO_FLUSH) then
      begin
        deflate_fast := need_more;
        exit;
      end;

      if (s.lookahead = 0) then
        break; { flush the current block }
    end;


    { Insert the AnsiString window[strstart .. strstart+2] in the
      dictionary, and set hash_head to the head of the hash chain: }

    if (s.lookahead >= MIN_MATCH) then
    begin
      INSERT_STRING(s, s.strstart, hash_head);
    end;

    { Find the longest match, discarding those <= prev_length.
      At this point we have always match_length < MIN_MATCH }
    if (hash_head <> ZNIL) and
       (s.strstart - hash_head <= (s.w_size-MIN_LOOKAHEAD){MAX_DIST}) then
    begin
      { To simplify the code, we prevent matches with the AnsiString
        of window index 0 (in particular we have to avoid a match
        of the AnsiString with itself at the start of the input file). }
      if (s.strategy <> Z_HUFFMAN_ONLY) then
      begin
        s.match_length := longest_match (s, hash_head);
      end;
      { longest_match() sets match_start }
    end;
    if (s.match_length >= MIN_MATCH) then
    begin
      {$IFDEF DEBUG}
      check_match(s, s.strstart, s.match_start, s.match_length);
      {$ENDIF}

      {_tr_tally_dist(s, s.strstart - s.match_start,
                        s.match_length - MIN_MATCH, bflush);}
      bflush := _tr_tally(s, s.strstart - s.match_start,
                        s.match_length - MIN_MATCH);

      Dec(s.lookahead, s.match_length);

      { Insert new strings in the hash table only if the match length
        is not too large. This saves time but degrades compression. }

{$ifndef FASTEST}
      if (s.match_length <= s.max_insert_length)
       and (s.lookahead >= MIN_MATCH) then
      begin
        Dec(s.match_length); { AnsiString at strstart already in hash table }
        repeat
          Inc(s.strstart);
          INSERT_STRING(s, s.strstart, hash_head);
          { strstart never exceeds WSIZE-MAX_MATCH, so there are
            always MIN_MATCH bytes ahead. }
          Dec(s.match_length);
        until (s.match_length = 0);
        Inc(s.strstart);
      end
      else
{$endif}

      begin
        Inc(s.strstart, s.match_length);
        s.match_length := 0;
        s.ins_h := s.window^[s.strstart];
        {UPDATE_HASH(s, s.ins_h, s.window[s.strstart+1]);}
        s.ins_h := (( s.ins_h shl s.hash_shift) xor
                     s.window^[s.strstart+1]) and s.hash_mask;
if MIN_MATCH <> 3 then   { the linker removes this }
begin
          {Call UPDATE_HASH() MIN_MATCH-3 more times}
end;

        { If lookahead < MIN_MATCH, ins_h is garbage, but it does not
          matter since it will be recomputed at next deflate call. }

      end;
    end
    else
    begin
      { No match, output a literal byte }
      {$IFDEF DEBUG}
      Tracevv(AnsiChar(s.window^[s.strstart]));
      {$ENDIF}
      {_tr_tally_lit (s, 0, s.window^[s.strstart], bflush);}
      bflush := _tr_tally (s, 0, s.window^[s.strstart]);

      Dec(s.lookahead);
      Inc(s.strstart);
    end;
    if bflush then
    begin  {FLUSH_BLOCK(s, FALSE);}
      FLUSH_BLOCK_ONLY(s, FALSE);
      if (s.strm^.avail_out = 0) then
      begin
        deflate_fast := need_more;
        exit;
      end;
    end;
  end;
  {FLUSH_BLOCK(s, flush = Z_FINISH);}
  FLUSH_BLOCK_ONLY(s, flush = Z_FINISH);
  if (s.strm^.avail_out = 0) then
  begin
    if flush = Z_FINISH then
      deflate_fast := finish_started
    else
      deflate_fast := need_more;
    exit;
  end;

  if flush = Z_FINISH then
    deflate_fast := finish_done
  else
    deflate_fast := block_done;
end;

{ ===========================================================================
  Same as above, but achieves better compression. We use a lazy
  evaluation for matches: a match is finally adopted only if there is
  no better match at the next window position. }

{local}
function deflate_slow(var s : deflate_state; flush : TsgInteger) : block_state;
var
  hash_head : IPos;       { head of hash chain }
  bflush : boolean;       { set if current block must be flushed }
var
  max_insert : uInt;
begin
  hash_head := ZNIL;

  { Process the input block. }
  while TRUE do
  begin
    { Make sure that we always have enough lookahead, except
      at the end of the input file. We need MAX_MATCH bytes
      for the next match, plus MIN_MATCH bytes to insert the
      AnsiString following the next match. }

    if (s.lookahead < MIN_LOOKAHEAD) then
    begin
      fill_window(s);
      if (s.lookahead < MIN_LOOKAHEAD) and (flush = Z_NO_FLUSH) then
      begin
        deflate_slow := need_more;
        exit;
      end;

      if (s.lookahead = 0) then
        break; { flush the current block }
    end;

    { Insert the AnsiString window[strstart .. strstart+2] in the
      dictionary, and set hash_head to the head of the hash chain: }

    if (s.lookahead >= MIN_MATCH) then
    begin
      INSERT_STRING(s, s.strstart, hash_head);
    end;

    { Find the longest match, discarding those <= prev_length. }

    s.prev_length := s.match_length;
    s.prev_match := s.match_start;
    s.match_length := MIN_MATCH-1;

    if (hash_head <> ZNIL) and (s.prev_length < s.max_lazy_match) and
       (s.strstart - hash_head <= {MAX_DIST}(s.w_size-MIN_LOOKAHEAD)) then
    begin
        { To simplify the code, we prevent matches with the AnsiString
          of window index 0 (in particular we have to avoid a match
          of the AnsiString with itself at the start of the input file). }

        if (s.strategy <> Z_HUFFMAN_ONLY) then
        begin
          s.match_length := longest_match (s, hash_head);
        end;
        { longest_match() sets match_start }

        if (s.match_length <= 5) and ((s.strategy = Z_FILTERED) or
             ((s.match_length = MIN_MATCH) and
              (s.strstart - s.match_start > TOO_FAR))) then
        begin
            { If prev_match is also MIN_MATCH, match_start is garbage
              but we will ignore the current match anyway. }

            s.match_length := MIN_MATCH-1;
        end;
    end;
    { If there was a match at the previous step and the current
      match is not better, output the previous match: }

    if (s.prev_length >= MIN_MATCH)
      and (s.match_length <= s.prev_length) then
    begin
      max_insert := s.strstart + s.lookahead - MIN_MATCH;
      { Do not insert strings in hash table beyond this. }
      {$ifdef DEBUG}
      check_match(s, s.strstart-1, s.prev_match, s.prev_length);
      {$endif}

      {_tr_tally_dist(s, s->strstart -1 - s->prev_match,
	                s->prev_length - MIN_MATCH, bflush);}
      bflush := _tr_tally(s, s.strstart -1 - s.prev_match,
                           s.prev_length - MIN_MATCH);

      { Insert in hash table all strings up to the end of the match.
        strstart-1 and strstart are already inserted. If there is not
        enough lookahead, the last two strings are not inserted in
        the hash table. }

      Dec(s.lookahead, s.prev_length-1);
      Dec(s.prev_length, 2);
      repeat
        Inc(s.strstart);
        if (s.strstart <= max_insert) then
        begin
          INSERT_STRING(s, s.strstart, hash_head);
        end;
        Dec(s.prev_length);
      until (s.prev_length = 0);
      s.match_available := FALSE;
      s.match_length := MIN_MATCH-1;
      Inc(s.strstart);

      if (bflush) then  {FLUSH_BLOCK(s, FALSE);}
      begin
        FLUSH_BLOCK_ONLY(s, FALSE);
        if (s.strm^.avail_out = 0) then
        begin
          deflate_slow := need_more;
          exit;
        end;
      end;
    end
    else
      if (s.match_available) then
      begin
        { If there was no match at the previous position, output a
          single literal. If there was a match but the current match
          is longer, truncate the previous match to a single literal. }
        {$IFDEF DEBUG}
        Tracevv(AnsiChar(s.window^[s.strstart-1]));
        {$ENDIF}
        bflush := _tr_tally (s, 0, s.window^[s.strstart-1]);

        if bflush then
        begin
          FLUSH_BLOCK_ONLY(s, FALSE);
        end;
        Inc(s.strstart);
        Dec(s.lookahead);
        if (s.strm^.avail_out = 0) then
        begin
          deflate_slow := need_more;
          exit;
        end;
      end
      else
      begin
        { There is no previous match to compare with, wait for
          the next step to decide. }

        s.match_available := TRUE;
        Inc(s.strstart);
        Dec(s.lookahead);
      end;
  end;

  {$IFDEF DEBUG}
  Assert (flush <> Z_NO_FLUSH, 'no flush?');
  {$ENDIF}
  if (s.match_available) then
  begin
    {$IFDEF DEBUG}
    Tracevv(AnsiChar(s.window^[s.strstart-1]));
    bflush :=
    {$ENDIF}
      _tr_tally (s, 0, s.window^[s.strstart-1]);
    s.match_available := FALSE;
  end;
  {FLUSH_BLOCK(s, flush = Z_FINISH);}
  FLUSH_BLOCK_ONLY(s, flush = Z_FINISH);
  if (s.strm^.avail_out = 0) then
  begin
    if flush = Z_FINISH then
      deflate_slow := finish_started
    else
      deflate_slow := need_more;
    exit;
  end;
  if flush = Z_FINISH then
    deflate_slow := finish_done
  else
    deflate_slow := block_done;
end;



end.
