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PasZip.pas
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PasZip.pas
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/// ZIP/LZ77 Deflate/Inflate Compression in pure pascal
// - this unit is a part of the freeware Synopse framework,
// licensed in the LGPL v3; version 1.18
unit PasZip;
{
This file is part of Synopse framework.
Synopse framework. Copyright (C) 2019 Arnaud Bouchez
Synopse Informatique - https://synopse.info
This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at
your option) any later version.
This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this library. If not, see <http://www.gnu.org/licenses/>.
PasZip.pas from madZip.pas - original version: 0.1b, date: 2003-06-09
clearly inspired from fpc's RTL paszlib
------------------------------------------------------------------------
compression stuff compatible with LZ77 Deflate/Inflate
Improvements by A.Bouchez on 2006-2010 - http://bouchez.info
- CRC32 table can be generated by code (save 1KB in executable)
- Inflate made 50% faster than MadLib's original by tuned Move() usage
and some critical part rewrite
- .zip reading from file, resource or direct memory - Windows only
- .zip write into a file (new .zip creation, not update) - Windows only
Version 1.18
- enhanced compatibility with new targets and compilers (Win32, Win64,
Delphi 2009+, FPC)
- even more refactoring, and fixes
- .zip supported for Windows only
}
{$WARNINGS OFF}
{$Q-,R-} // Turn range checking and overflow checking off
{ $D-,L-}
{$I Synopse.inc}
interface
uses
{$ifdef MSWINDOWS}
Windows,
{$else}
Types,
{$endif}
SysUtils;
type
{$ifdef HASCODEPAGE}
RawByteZip = RawByteString;
TZipName = type AnsiString(437);
{$else}
RawByteZip = AnsiString;
TZipName = AnsiString;
{$endif}
{$ifdef DELPHI5OROLDER}
PCardinal = ^cardinal;
{$endif}
/// compress memory using the ZLib DEFLATE algorithm
function CompressMem(src, dst: pointer; srcLen, dstLen: integer): integer;
/// uncompress memory using the ZLib INFLATE algorithm
function UnCompressMem(src, dst: pointer; srcLen, dstLen: integer): integer;
/// compress memory using the ZLib DEFLATE algorithm with a crc32 checksum
function CompressString(const data: RawByteZip; failIfGrow: boolean = false): RawByteZip;
/// uncompress memory using the ZLib INFLATE algorithm, checking crc32 checksum
function UncompressString(const data: RawByteZip): RawByteZip;
{$ifdef MSWINDOWS} { use Windows MapFile }
function CompressFile(const srcFile, dstFile: TFileName; failIfGrow: boolean = false): boolean;
function UncompressFile(const srcFile, dstFile: TFileName;
lastWriteTime: int64 = 0; attr: dword = 0): boolean;
function GetCompressedFileInfo(const comprFile: TFileName; var size: int64;
var crc32: dword): boolean;
function GetUncompressedFileInfo(const uncomprFile: TFileName; var size: int64;
var crc32: dword): boolean;
function IsCompressedFileEqual(const uncomprFile, comprFile: TFileName): boolean;
/// You can create a "zip" compatible archive by calling the "Zip" function.
// - The first parameter is the full file path of the new zip archive.
// - The second parameter must be an array of the files you want to have zipped
// into the archive (full file path again, please).
// - The third array (only file names, please) allows you to store the files into
// the zip under a different name.
// - Generally the resulting zip archive should not contain any directory structure:
// all zipped files are directly stored in the archive's root, if NoSubDirectories
// is set to TRUE.
function Zip(const zip: TFileName; const files, zipAs: array of TFileName;
NoSubDirectories: boolean = false): boolean;
/// create a void .zip file
procedure CreateVoidZip(const aFileName: TFileName);
{$endif MSWINDOWS}
/// create a compatible .gz file (returns file size)
function GzCompress(src: pointer; srcLen: integer; const fName: TFileName): cardinal;
/// calculate the CRC32 hash of a specified memory buffer
function UpdateCrc32(aCRC32: cardinal; inBuf: pointer; inLen: integer): cardinal;
{$DEFINE DYNAMIC_CRC_TABLE}
{ if defined, the crc32Tab[] is created on staturp: save 1KB of code size }
type
TCRC32Tab = array[0..255] of cardinal;
/// the static buffer used for fast CRC32 hashing
{$ifdef DYNAMIC_CRC_TABLE}
var
crc32Tab: TCRC32Tab;
{$else}
const
crc32Tab: TCRC32Tab = ($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}
{$ifdef MSWINDOWS}
type
/// generic file information structure, as used in .zip file format
// - used in any header, contains info about following block
TFileInfo = packed record
neededVersion: word; // $14
flags: word; // 0
zzipMethod: word; // 8 (deflate)
zlastModTime: word; // dos format
zlastModDate: word; // dos format
zcrc32: dword;
zzipSize: dword;
zfullSize: dword;
nameLen: word; // length(name)
extraLen: word; // 0
end;
PFileInfo = ^TFileInfo;
/// internal file information structure, as used in .zip file format
// - used locally inside the file stream, followed by the name and then the data
TLocalFileHeader = packed record
signature: dword; // $04034b50
fileInfo: TFileInfo;
end;
/// directory file information structure, as used in .zip file format
// - used at the end of the zip file to recap all entries
TFileHeader = packed record
signature: dword; // $02014b50
madeBy: word; // $14
fileInfo: TFileInfo;
commentLen: word; // 0
firstDiskNo: word; // 0
intFileAttr: word; // 0 = binary; 1 = text
extFileAttr: dword; // dos file attributes
localHeadOff: dword; // @TLocalFileHeader
end;
/// last header structure, as used in .zip file format
// - this header ends the file and is used to find the TFileHeader entries
TLastHeader = packed record
signature: dword; // $06054b50
thisDisk: word; // 0
headerDisk: word; // 0
thisFiles: word; // 1
totalFiles: word; // 1
headerSize: dword; // sizeOf(TFileHeaders + names)
headerOffset: dword; // @TFileHeader
commentLen: word; // 0
end;
type
/// stores an entry of a file inside a .zip archive
TZipEntry = packed record
/// the information of this file, as stored in the .zip archive
info: PFileInfo;
/// points to the compressed data in the .zip archive, mapped in memory
data: PAnsiChar;
/// ASCIIZ name of the file inside the .zip archive
// - not a string, but a fixed-length array of char
Name: array[0..127 - SizeOf(pointer)*2] of AnsiChar;
end;
/// read-only access to a .zip archive file
// - can open directly a specified .zip file (will be memory mapped for fast access)
// - can open a .zip archive file content from a resource (embedded in the executable)
// - can open a .zip archive file content from memory
TZipRead = class
private
file_, map: dword; // we use a memory mapped file to access the zip content
buf: PByteArray;
fZipStartOffset: cardinal;
fShowMessageBoxOnError: boolean;
procedure UnMap;
public
/// the number of files inside a .zip archive
Count: integer;
/// the files inside the .zip archive
Entry: array of TZipEntry;
/// open a .zip archive file as Read Only
constructor Create(const aFileName: TFileName; ZipStartOffset: cardinal = 0;
Size: cardinal = 0; ShowMessageBoxOnError: boolean = true); overload;
/// open a .zip archive file directly from a resource
constructor Create(Instance: THandle; const ResName: string; ResType: PChar); overload;
/// open a .zip archive file directly from memory
constructor Create(BufZip: pByteArray; Size: cardinal); overload;
/// release associated memory
destructor Destroy; override;
/// get the index of a file inside the .zip archive
function NameToIndex(const aZipName: TZipName): integer;
/// uncompress a file stored inside the .zip archive into a destination folder
function UnZipFile(aIndex: integer; DestPath: TFileName; ForceWriteFlush:
boolean): boolean;
/// uncompress a file stored inside the .zip archive into memory
function UnZip(aIndex: integer): RawByteZip; overload;
/// read the file from the supplied folder, and check its content according
// to the crc32 stored inside the .zip archive header (no decompression is made)
function CheckFile(aIndex: integer; DestPath: TFileName): boolean;
/// get any initial .exe file
function GetInitialExeContent: RawByteZip;
/// the starting offset of the .zip content, after the initial .exe, if any
// - can be used to copy the initial .exe file
property ZipStartOffset: cardinal read fZipStartOffset;
end;
/// write-only access for creating a .zip archive file
// - not to be used to update a .zip file, but to create a new one
// - update can be done manualy by using a TZipRead instance and the
// AddFromZip() method
TZipWrite = class
protected
fAppendOffset: cardinal;
fFileName: TFileName;
fMagic: cardinal;
public
/// the associated file handle
Handle: integer;
/// the total number of entries
Count: integer;
/// the resulting file entries
Entry: array of record
/// the file name
name: TZipName;
/// the corresponding file header
fhr: TFileHeader;
end;
/// initialize the .zip file
constructor Create(const aFileName: TFileName); overload;
/// compress (using the deflate method) a memory buffer, and add it to the zip file
// - by default, the 1st of January, 2010 is used if not date is supplied
procedure AddDeflated(const aZipName: TZipName; Buf: pointer; Size:
integer; CompressLevel: integer = 6; FileAge: integer = 1 + 1 shl 5 + 30
shl 9); overload;
/// compress (using the deflate method) a file, and add it to the zip file
procedure AddDeflated(const aFileName: TFileName; RemovePath: boolean = true;
CompressLevel: integer = 6); overload;
/// add a memory buffer to the zip file, without compression
// - content is stored, not deflated
// (in that case, no deflate code is added to the executable)
// - by default, the 1st of January, 2010 is used if not date is supplied
procedure AddStored(const aZipName: TZipName; Buf: pointer; Size: integer;
FileAge: integer = 1 + 1 shl 5 + 30 shl 9);
/// add a file from an already compressed zip entry
procedure AddFromZip(const ZipEntry: TZipEntry);
/// append a file content into the destination file
// - useful to add the initial Setup.exe file, e.g.
procedure Append(const Content: RawByteZip);
/// release associated memory, and close destination file
destructor Destroy; override;
end;
{$endif MSWINDOWS}
implementation
{$ifndef FPC}
type
PtrUInt = {$ifdef CPU64}NativeUInt{$else}cardinal{$endif};
{$endif FPC}
// special tuned Move() routine, including data overlap bug correction
{$ifdef PUREPASCAL}
procedure MoveWithOverlap(Src: PByte; Dst: PByte; Count: PtrUInt);
{$ifdef HASINLINE}inline;{$endif}
begin // should be fast enough in practice, especially inlined
dec(PtrUInt(Src), PtrUInt(Dst));
inc(Count, PtrUInt(Dst));
repeat
Dst^ := PByteArray(Src)[PtrUInt(Dst)];
inc(Dst);
until PtrUInt(Dst)=Count;
end;
{$else}
procedure MoveWithOverlap(Src: PByte; Dst: PByte; Count: Integer);
asm // eax=source edx=dest ecx=count
push edx
sub edx, eax
cmp edx, ecx // avoid move error if dest and source overlaps
pop edx // restore original edx=dest
ja System.Move // call FastMove() routine for normal code
or ecx, ecx
jz @@Exit
push edi
mov edi, edx // restore original edi=dest
@@overlap: // byte by byte slower but accurate move routine
mov dl, [eax]
inc eax
mov [edi], dl
inc edi
dec ecx
jnz @@overlap
pop edi
@@Exit:
end;
{$endif}
//----------------- general library stuff
const
CMemLevel = 8;
CWindowBits = 15;
type
TPInt64 = ^int64;
TPCardinal = ^cardinal;
TPWord = ^word;
TAByte = array[0..maxInt - 1] of byte;
TPAByte = ^TAByte;
TAWord = array[0..maxInt shr 1 - 1] of word;
TPAWord = ^TAWord;
TAInteger = array[0..maxInt shr 2 - 1] of integer;
TPAInteger = ^TAInteger;
TACardinal = array[0..maxInt shr 2 - 1] of cardinal;
TPACardinal = ^TACardinal;
TAInt64 = array[0..maxInt shr 3 - 1] of int64;
TPAInt64 = ^TAInt64;
PInflateHuft = ^TInflateHuft;
TInflateHuft = packed record
Exop, // number of extra bits or operation
Bits: Byte; // number of bits in this code or subcode
Base: Cardinal; // literal, Length base, or distance base or table offset
end;
THuftFields = array[0..(MaxInt div SizeOf(TInflateHuft)) - 1] of TInflateHuft;
PHuftField = ^THuftFields;
PPInflateHuft = ^PInflateHuft;
TInflateCodesMode = ( // waiting for "I:"=input, "O:"=output, "X:"=nothing
icmStart, // X: set up for Len
icmLen, // I: get length/literal/eob next
icmLenNext, // I: getting length extra (have base)
icmDistance, // I: get distance next
icmDistExt, // I: getting distance extra
icmCopy, // O: copying bytes in window, waiting for space
icmLit, // O: got literal, waiting for output space
icmWash, // O: got eob, possibly still output waiting
icmZEnd, // X: got eob and all data flushed
icmBadCode // X: got error
);
// inflate codes private state
PInflateCodesState = ^TInflateCodesState;
TInflateCodesState = record
Mode: TInflateCodesMode; // current inflate codes mode
// mode dependent information
Len: Cardinal;
Sub: record // submode
case Byte of
0:(Code: record // if Len or Distance, where in tree
Tree: PInflateHuft; // pointer into tree
need: Cardinal; // bits needed
end);
1:(lit: Cardinal); // if icmLit, literal
2:(copy: record // if EXT or icmCopy, where and how much
get: Cardinal; // bits to get for extra
Distance: Cardinal; // distance back to copy from
end);
end;
// mode independent information
LiteralTreeBits: Byte; // LiteralTree bits decoded per branch
DistanceTreeBits: Byte; // DistanceTree bits decoder per branch
LiteralTree: PInflateHuft; // literal/length/eob tree
DistanceTree: PInflateHuft; // distance tree
end;
TInflateBlockMode = (ibmZType, // get type bits (3, including end bit)
ibmLens, // get lengths for stored
ibmStored, // processing stored block
ibmTable, // get table lengths
ibmBitTree, // get bit lengths tree for a dynamic block
ibmDistTree, // get length, distance trees for a dynamic block
ibmCodes, // processing fixed or dynamic block
ibmDry, // output remaining window bytes
ibmBlockDone, // finished last block, done
ibmBlockBad // got a data error -> stuck here
);
// inflate blocks semi-private state
PInflateBlocksState = ^TInflateBlocksState;
TInflateBlocksState = record
Mode: TInflateBlockMode; // current inflate block mode
// mode dependent information
Sub: record // submode
case Byte of
0: (left: Cardinal); // if ibmStored, bytes left to copy
1: (Trees: record // if DistanceTree, decoding info for trees
Table: Cardinal; // table lengths (14 Bits)
Index: Cardinal; // index into blens (or BitOrder)
blens: TPACardinal; // bit lengths of codes
BB: Cardinal; // bit length tree depth
TB: PInflateHuft; // bit length decoding tree
end);
2: (decode: record // if ibmCodes, current state
TL: PInflateHuft;
TD: PInflateHuft; // trees to free
codes: PInflateCodesState;
end);
end;
Last: Boolean; // True if this block is the last block
// mode independent information
bitk: Cardinal; // bits in bit buffer
bitb: Cardinal; // bit buffer
hufts: PHuftField; // single allocation for tree space
window: PByte; // sliding window
zend: PByte; // one byte after sliding window
read: PByte; // window read pointer
write: PByte; // window write pointer
end;
// The application must update NextInput and AvailableInput when AvailableInput has dropped to zero. It must update
// NextOutput and AvailableOutput when AvailableOutput has dropped to zero. All other fields are set by the
// compression library and must not be updated by the application.
//
// The fields TotalInput and TotalOutput can be used for statistics or progress reports. After compression, TotalInput
// 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).
PZState = ^TZState;
TZState = record
NextInput: PByte; // next input byte
AvailableInput: Cardinal; // number of bytes available at NextInput
TotalInput: Cardinal; // total number of input bytes read so far
NextOutput: PByte; // next output byte should be put there
AvailableOutput: Cardinal; // remaining free space at NextOutput
TotalOutput: Cardinal; // total number of bytes output so far
State: PInflateBlocksState; // not visible by applications
end;
const
// Return codes for the compression/decompression functions. Negative
// values are errors, positive values are used for special but normal events.
Z_OK = 0;
Z_STREAM_END = 1;
Z_STREAM_ERROR = -2;
Z_DATA_ERROR = -3;
Z_MEM_ERROR = -4;
Z_BUF_ERROR = -5;
// three kinds of block type
STORED_BLOCK = 0;
STATIC_TREES = 1;
DYN_TREES = 2;
// minimum and maximum match lengths
MIN_MATCH = 3;
MAX_MATCH = 258;
//----------------- deflation support
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
type
// data structure describing a single value and its code string
PTreeEntry = ^TTreeEntry;
TTreeEntry = record
fc: record
case Byte of
0:
(Frequency: Word); // frequency count
1:
(Code: Word); // bit string
end;
dl: record
case Byte of
0:
(dad: Word); // father node in Huffman tree
1:
(Len: Word); // length of bit string
end;
end;
TLiteralTree = array[0..HEAP_SIZE - 1] of TTreeEntry; // literal and length tree
TDistanceTree = array[0..2 * D_CODES] of TTreeEntry; // distance tree
THuffmanTree = array[0..2 * BL_CODES] of TTreeEntry; // Huffman tree for bit lengths
PTree = ^TTree;
TTree = array[0..(MaxInt div SizeOf(TTreeEntry)) - 1] of TTreeEntry; // generic tree type
PStaticTreeDescriptor = ^TStaticTreeDescriptor;
TStaticTreeDescriptor = record
StaticTree: PTree; // static tree or nil
ExtraBits: TPAInteger; // extra bits for each code or nil
ExtraBase: Integer; // base index for ExtraBits
Elements: Integer; // max number of elements in the tree
MaxLength: Integer; // max bit length for the codes
end;
PTreeDescriptor = ^TTreeDescriptor;
TTreeDescriptor = record
DynamicTree: PTree;
MaxCode: Integer; // largest code with non zero frequency
StaticDescriptor: PStaticTreeDescriptor; // the corresponding static tree
end;
PDeflateState = ^TDeflateState;
TDeflateState = record
ZState: PZState; // pointer back to this zlib stream
PendingBuffer: TPAByte; // output still pending
PendingBufferSize: Integer;
PendingOutput: PByte; // next pending byte to output to the stream
Pending: Integer; // nb of bytes in the pending buffer
WindowSize: Cardinal; // LZ77 window size (32K by default)
WindowBits: Cardinal; // log2(WindowSize) (8..16)
WindowMask: Cardinal; // WindowSize - 1
// 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: TPAByte;
// Actual size of Window: 2 * WSize, except when the user input buffer
// is directly used as sliding window.
CurrentWindowSize: Integer;
// Link to older string 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.
Previous: TPAWord;
Head: TPAWord; // heads of the hash chains or nil
InsertHash: Cardinal; // hash index of string to be inserted
HashSize: Cardinal; // number of elements in hash table
HashBits: Cardinal; // log2(HashSize)
HashMask: Cardinal; // HashSize - 1
// Number of bits by which InsertHash 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:
// HashShift * MIN_MATCH >= HashBits
HashShift: Cardinal;
// Window position at the beginning of the current output block. Gets
// negative when the window is moved backwards.
BlockStart: Integer;
MatchLength: Cardinal; // length of best match
PreviousMatch: Cardinal; // previous match
MatchAvailable: Boolean; // set if previous match exists
StringStart: Cardinal; // start of string to insert
MatchStart: Cardinal; // start of matching string
Lookahead: Cardinal; // number of valid bytes ahead in window
// Length of the best match at previous step. Matches not greater than this
// are discarded. This is used in the lazy match evaluation.
PreviousLength: Cardinal;
LiteralTree: TLiteralTree; // literal and length tree
DistanceTree: TDistanceTree; // distance tree
BitLengthTree: THuffmanTree; // Huffman tree for bit lengths
LiteralDescriptor: TTreeDescriptor; // Descriptor for literal tree
DistanceDescriptor: TTreeDescriptor; // Descriptor for distance tree
BitLengthDescriptor: TTreeDescriptor; // Descriptor for bit length tree
BitLengthCounts: array[0..MAX_BITS] of Word; // number of codes at each bit length for an optimal tree
Heap: array[0..2 * L_CODES] of Integer; // heap used to build the Huffman trees
HeapLength: Integer; // number of elements in the heap
HeapMaximum: Integer; // 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] of Byte; // depth of each subtree used as tie breaker for trees of equal frequency
LiteralBuffer: TPAByte; // buffer for literals or lengths
// Size of match buffer for literals/lengths. There are 4 reasons for limiting LiteralBufferSize 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 LiteralBufferSize 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 string table.) Smaller buffer sizes give
// fast adaptation but have of course the overhead of transmitting
// trees more frequently.
// - I can't count above 4
LiteralBufferSize: Cardinal;
LastLiteral: Cardinal; // running index in LiteralBuffer
// Buffer for distances. To simplify the code, DistanceBuffer and LiteralBuffer have
// the same number of elements. To use different lengths, an extra flag array would be necessary.
DistanceBuffer: TPAWord;
OptimalLength: Integer; // bit length of current block with optimal trees
StaticLength: Integer; // bit length of current block with static trees
CompressedLength: Integer; // total bit length of compressed file
Matches: Cardinal; // number of string matches in current block
LastEOBLength: Integer; // bit length of EOB code for last block
BitsBuffer: Word; // Output buffer. Bits are inserted starting at the bottom (least significant bits).
ValidBits: Integer; // Number of valid bits in BitsBuffer. All Bits above the last valid bit are always zero.
end;
//----------------- Huffmann trees
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 TreeInit below).
StaticLiteralTree: array[0..L_CODES + 1] of TTreeEntry = (
(fc: (Frequency: 12); dl: (Len: 8)), (fc: (Frequency: 140); dl: (Len: 8)), (fc: (Frequency: 76); dl: (Len: 8)),
(fc: (Frequency: 204); dl: (Len: 8)), (fc: (Frequency: 44); dl: (Len: 8)), (fc: (Frequency: 172); dl: (Len: 8)),
(fc: (Frequency: 108); dl: (Len: 8)), (fc: (Frequency: 236); dl: (Len: 8)), (fc: (Frequency: 28); dl: (Len: 8)),
(fc: (Frequency: 156); dl: (Len: 8)), (fc: (Frequency: 92); dl: (Len: 8)), (fc: (Frequency: 220); dl: (Len: 8)),
(fc: (Frequency: 60); dl: (Len: 8)), (fc: (Frequency: 188); dl: (Len: 8)), (fc: (Frequency: 124); dl: (Len: 8)),
(fc: (Frequency: 252); dl: (Len: 8)), (fc: (Frequency: 2); dl: (Len: 8)), (fc: (Frequency: 130); dl: (Len: 8)),
(fc: (Frequency: 66); dl: (Len: 8)), (fc: (Frequency: 194); dl: (Len: 8)), (fc: (Frequency: 34); dl: (Len: 8)),
(fc: (Frequency: 162); dl: (Len: 8)), (fc: (Frequency: 98); dl: (Len: 8)), (fc: (Frequency: 226); dl: (Len: 8)),
(fc: (Frequency: 18); dl: (Len: 8)), (fc: (Frequency: 146); dl: (Len: 8)), (fc: (Frequency: 82); dl: (Len: 8)),
(fc: (Frequency: 210); dl: (Len: 8)), (fc: (Frequency: 50); dl: (Len: 8)), (fc: (Frequency: 178); dl: (Len: 8)),
(fc: (Frequency: 114); dl: (Len: 8)), (fc: (Frequency: 242); dl: (Len: 8)), (fc: (Frequency: 10); dl: (Len: 8)),
(fc: (Frequency: 138); dl: (Len: 8)), (fc: (Frequency: 74); dl: (Len: 8)), (fc: (Frequency: 202); dl: (Len: 8)),
(fc: (Frequency: 42); dl: (Len: 8)), (fc: (Frequency: 170); dl: (Len: 8)), (fc: (Frequency: 106); dl: (Len: 8)),
(fc: (Frequency: 234); dl: (Len: 8)), (fc: (Frequency: 26); dl: (Len: 8)), (fc: (Frequency: 154); dl: (Len: 8)),
(fc: (Frequency: 90); dl: (Len: 8)), (fc: (Frequency: 218); dl: (Len: 8)), (fc: (Frequency: 58); dl: (Len: 8)),
(fc: (Frequency: 186); dl: (Len: 8)), (fc: (Frequency: 122); dl: (Len: 8)), (fc: (Frequency: 250); dl: (Len: 8)),
(fc: (Frequency: 6); dl: (Len: 8)), (fc: (Frequency: 134); dl: (Len: 8)), (fc: (Frequency: 70); dl: (Len: 8)),
(fc: (Frequency: 198); dl: (Len: 8)), (fc: (Frequency: 38); dl: (Len: 8)), (fc: (Frequency: 166); dl: (Len: 8)),
(fc: (Frequency: 102); dl: (Len: 8)), (fc: (Frequency: 230); dl: (Len: 8)), (fc: (Frequency: 22); dl: (Len: 8)),
(fc: (Frequency: 150); dl: (Len: 8)), (fc: (Frequency: 86); dl: (Len: 8)), (fc: (Frequency: 214); dl: (Len: 8)),
(fc: (Frequency: 54); dl: (Len: 8)), (fc: (Frequency: 182); dl: (Len: 8)), (fc: (Frequency: 118); dl: (Len: 8)),
(fc: (Frequency: 246); dl: (Len: 8)), (fc: (Frequency: 14); dl: (Len: 8)), (fc: (Frequency: 142); dl: (Len: 8)),
(fc: (Frequency: 78); dl: (Len: 8)), (fc: (Frequency: 206); dl: (Len: 8)), (fc: (Frequency: 46); dl: (Len: 8)),
(fc: (Frequency: 174); dl: (Len: 8)), (fc: (Frequency: 110); dl: (Len: 8)), (fc: (Frequency: 238); dl: (Len: 8)),
(fc: (Frequency: 30); dl: (Len: 8)), (fc: (Frequency: 158); dl: (Len: 8)), (fc: (Frequency: 94); dl: (Len: 8)),
(fc: (Frequency: 222); dl: (Len: 8)), (fc: (Frequency: 62); dl: (Len: 8)), (fc: (Frequency: 190); dl: (Len: 8)),
(fc: (Frequency: 126); dl: (Len: 8)), (fc: (Frequency: 254); dl: (Len: 8)), (fc: (Frequency: 1); dl: (Len: 8)),
(fc: (Frequency: 129); dl: (Len: 8)), (fc: (Frequency: 65); dl: (Len: 8)), (fc: (Frequency: 193); dl: (Len: 8)),
(fc: (Frequency: 33); dl: (Len: 8)), (fc: (Frequency: 161); dl: (Len: 8)), (fc: (Frequency: 97); dl: (Len: 8)),
(fc: (Frequency: 225); dl: (Len: 8)), (fc: (Frequency: 17); dl: (Len: 8)), (fc: (Frequency: 145); dl: (Len: 8)),
(fc: (Frequency: 81); dl: (Len: 8)), (fc: (Frequency: 209); dl: (Len: 8)), (fc: (Frequency: 49); dl: (Len: 8)),
(fc: (Frequency: 177); dl: (Len: 8)), (fc: (Frequency: 113); dl: (Len: 8)), (fc: (Frequency: 241); dl: (Len: 8)),
(fc: (Frequency: 9); dl: (Len: 8)), (fc: (Frequency: 137); dl: (Len: 8)), (fc: (Frequency: 73); dl: (Len: 8)),
(fc: (Frequency: 201); dl: (Len: 8)), (fc: (Frequency: 41); dl: (Len: 8)), (fc: (Frequency: 169); dl: (Len: 8)),
(fc: (Frequency: 105); dl: (Len: 8)), (fc: (Frequency: 233); dl: (Len: 8)), (fc: (Frequency: 25); dl: (Len: 8)),
(fc: (Frequency: 153); dl: (Len: 8)), (fc: (Frequency: 89); dl: (Len: 8)), (fc: (Frequency: 217); dl: (Len: 8)),
(fc: (Frequency: 57); dl: (Len: 8)), (fc: (Frequency: 185); dl: (Len: 8)), (fc: (Frequency: 121); dl: (Len: 8)),
(fc: (Frequency: 249); dl: (Len: 8)), (fc: (Frequency: 5); dl: (Len: 8)), (fc: (Frequency: 133); dl: (Len: 8)),
(fc: (Frequency: 69); dl: (Len: 8)), (fc: (Frequency: 197); dl: (Len: 8)), (fc: (Frequency: 37); dl: (Len: 8)),
(fc: (Frequency: 165); dl: (Len: 8)), (fc: (Frequency: 101); dl: (Len: 8)), (fc: (Frequency: 229); dl: (Len: 8)),
(fc: (Frequency: 21); dl: (Len: 8)), (fc: (Frequency: 149); dl: (Len: 8)), (fc: (Frequency: 85); dl: (Len: 8)),
(fc: (Frequency: 213); dl: (Len: 8)), (fc: (Frequency: 53); dl: (Len: 8)), (fc: (Frequency: 181); dl: (Len: 8)),
(fc: (Frequency: 117); dl: (Len: 8)), (fc: (Frequency: 245); dl: (Len: 8)), (fc: (Frequency: 13); dl: (Len: 8)),
(fc: (Frequency: 141); dl: (Len: 8)), (fc: (Frequency: 77); dl: (Len: 8)), (fc: (Frequency: 205); dl: (Len: 8)),
(fc: (Frequency: 45); dl: (Len: 8)), (fc: (Frequency: 173); dl: (Len: 8)), (fc: (Frequency: 109); dl: (Len: 8)),
(fc: (Frequency: 237); dl: (Len: 8)), (fc: (Frequency: 29); dl: (Len: 8)), (fc: (Frequency: 157); dl: (Len: 8)),
(fc: (Frequency: 93); dl: (Len: 8)), (fc: (Frequency: 221); dl: (Len: 8)), (fc: (Frequency: 61); dl: (Len: 8)),
(fc: (Frequency: 189); dl: (Len: 8)), (fc: (Frequency: 125); dl: (Len: 8)), (fc: (Frequency: 253); dl: (Len: 8)),
(fc: (Frequency: 19); dl: (Len: 9)), (fc: (Frequency: 275); dl: (Len: 9)), (fc: (Frequency: 147); dl: (Len: 9)),
(fc: (Frequency: 403); dl: (Len: 9)), (fc: (Frequency: 83); dl: (Len: 9)), (fc: (Frequency: 339); dl: (Len: 9)),
(fc: (Frequency: 211); dl: (Len: 9)), (fc: (Frequency: 467); dl: (Len: 9)), (fc: (Frequency: 51); dl: (Len: 9)),
(fc: (Frequency: 307); dl: (Len: 9)), (fc: (Frequency: 179); dl: (Len: 9)), (fc: (Frequency: 435); dl: (Len: 9)),
(fc: (Frequency: 115); dl: (Len: 9)), (fc: (Frequency: 371); dl: (Len: 9)), (fc: (Frequency: 243); dl: (Len: 9)),
(fc: (Frequency: 499); dl: (Len: 9)), (fc: (Frequency: 11); dl: (Len: 9)), (fc: (Frequency: 267); dl: (Len: 9)),
(fc: (Frequency: 139); dl: (Len: 9)), (fc: (Frequency: 395); dl: (Len: 9)), (fc: (Frequency: 75); dl: (Len: 9)),
(fc: (Frequency: 331); dl: (Len: 9)), (fc: (Frequency: 203); dl: (Len: 9)), (fc: (Frequency: 459); dl: (Len: 9)),
(fc: (Frequency: 43); dl: (Len: 9)), (fc: (Frequency: 299); dl: (Len: 9)), (fc: (Frequency: 171); dl: (Len: 9)),
(fc: (Frequency: 427); dl: (Len: 9)), (fc: (Frequency: 107); dl: (Len: 9)), (fc: (Frequency: 363); dl: (Len: 9)),
(fc: (Frequency: 235); dl: (Len: 9)), (fc: (Frequency: 491); dl: (Len: 9)), (fc: (Frequency: 27); dl: (Len: 9)),
(fc: (Frequency: 283); dl: (Len: 9)), (fc: (Frequency: 155); dl: (Len: 9)), (fc: (Frequency: 411); dl: (Len: 9)),
(fc: (Frequency: 91); dl: (Len: 9)), (fc: (Frequency: 347); dl: (Len: 9)), (fc: (Frequency: 219); dl: (Len: 9)),
(fc: (Frequency: 475); dl: (Len: 9)), (fc: (Frequency: 59); dl: (Len: 9)), (fc: (Frequency: 315); dl: (Len: 9)),
(fc: (Frequency: 187); dl: (Len: 9)), (fc: (Frequency: 443); dl: (Len: 9)), (fc: (Frequency: 123); dl: (Len: 9)),
(fc: (Frequency: 379); dl: (Len: 9)), (fc: (Frequency: 251); dl: (Len: 9)), (fc: (Frequency: 507); dl: (Len: 9)),
(fc: (Frequency: 7); dl: (Len: 9)), (fc: (Frequency: 263); dl: (Len: 9)), (fc: (Frequency: 135); dl: (Len: 9)),
(fc: (Frequency: 391); dl: (Len: 9)), (fc: (Frequency: 71); dl: (Len: 9)), (fc: (Frequency: 327); dl: (Len: 9)),
(fc: (Frequency: 199); dl: (Len: 9)), (fc: (Frequency: 455); dl: (Len: 9)), (fc: (Frequency: 39); dl: (Len: 9)),
(fc: (Frequency: 295); dl: (Len: 9)), (fc: (Frequency: 167); dl: (Len: 9)), (fc: (Frequency: 423); dl: (Len: 9)),
(fc: (Frequency: 103); dl: (Len: 9)), (fc: (Frequency: 359); dl: (Len: 9)), (fc: (Frequency: 231); dl: (Len: 9)),
(fc: (Frequency: 487); dl: (Len: 9)), (fc: (Frequency: 23); dl: (Len: 9)), (fc: (Frequency: 279); dl: (Len: 9)),
(fc: (Frequency: 151); dl: (Len: 9)), (fc: (Frequency: 407); dl: (Len: 9)), (fc: (Frequency: 87); dl: (Len: 9)),
(fc: (Frequency: 343); dl: (Len: 9)), (fc: (Frequency: 215); dl: (Len: 9)), (fc: (Frequency: 471); dl: (Len: 9)),
(fc: (Frequency: 55); dl: (Len: 9)), (fc: (Frequency: 311); dl: (Len: 9)), (fc: (Frequency: 183); dl: (Len: 9)),
(fc: (Frequency: 439); dl: (Len: 9)), (fc: (Frequency: 119); dl: (Len: 9)), (fc: (Frequency: 375); dl: (Len: 9)),
(fc: (Frequency: 247); dl: (Len: 9)), (fc: (Frequency: 503); dl: (Len: 9)), (fc: (Frequency: 15); dl: (Len: 9)),
(fc: (Frequency: 271); dl: (Len: 9)), (fc: (Frequency: 143); dl: (Len: 9)), (fc: (Frequency: 399); dl: (Len: 9)),
(fc: (Frequency: 79); dl: (Len: 9)), (fc: (Frequency: 335); dl: (Len: 9)), (fc: (Frequency: 207); dl: (Len: 9)),
(fc: (Frequency: 463); dl: (Len: 9)), (fc: (Frequency: 47); dl: (Len: 9)), (fc: (Frequency: 303); dl: (Len: 9)),
(fc: (Frequency: 175); dl: (Len: 9)), (fc: (Frequency: 431); dl: (Len: 9)), (fc: (Frequency: 111); dl: (Len: 9)),
(fc: (Frequency: 367); dl: (Len: 9)), (fc: (Frequency: 239); dl: (Len: 9)), (fc: (Frequency: 495); dl: (Len: 9)),
(fc: (Frequency: 31); dl: (Len: 9)), (fc: (Frequency: 287); dl: (Len: 9)), (fc: (Frequency: 159); dl: (Len: 9)),
(fc: (Frequency: 415); dl: (Len: 9)), (fc: (Frequency: 95); dl: (Len: 9)), (fc: (Frequency: 351); dl: (Len: 9)),
(fc: (Frequency: 223); dl: (Len: 9)), (fc: (Frequency: 479); dl: (Len: 9)), (fc: (Frequency: 63); dl: (Len: 9)),
(fc: (Frequency: 319); dl: (Len: 9)), (fc: (Frequency: 191); dl: (Len: 9)), (fc: (Frequency: 447); dl: (Len: 9)),
(fc: (Frequency: 127); dl: (Len: 9)), (fc: (Frequency: 383); dl: (Len: 9)), (fc: (Frequency: 255); dl: (Len: 9)),
(fc: (Frequency: 511); dl: (Len: 9)), (fc: (Frequency: 0); dl: (Len: 7)), (fc: (Frequency: 64); dl: (Len: 7)),
(fc: (Frequency: 32); dl: (Len: 7)), (fc: (Frequency: 96); dl: (Len: 7)), (fc: (Frequency: 16); dl: (Len: 7)),
(fc: (Frequency: 80); dl: (Len: 7)), (fc: (Frequency: 48); dl: (Len: 7)), (fc: (Frequency: 112); dl: (Len: 7)),
(fc: (Frequency: 8); dl: (Len: 7)), (fc: (Frequency: 72); dl: (Len: 7)), (fc: (Frequency: 40); dl: (Len: 7)),
(fc: (Frequency: 104); dl: (Len: 7)), (fc: (Frequency: 24); dl: (Len: 7)), (fc: (Frequency: 88); dl: (Len: 7)),
(fc: (Frequency: 56); dl: (Len: 7)), (fc: (Frequency: 120); dl: (Len: 7)), (fc: (Frequency: 4); dl: (Len: 7)),
(fc: (Frequency: 68); dl: (Len: 7)), (fc: (Frequency: 36); dl: (Len: 7)), (fc: (Frequency: 100); dl: (Len: 7)),
(fc: (Frequency: 20); dl: (Len: 7)), (fc: (Frequency: 84); dl: (Len: 7)), (fc: (Frequency: 52); dl: (Len: 7)),
(fc: (Frequency: 116); dl: (Len: 7)), (fc: (Frequency: 3); dl: (Len: 8)), (fc: (Frequency: 131); dl: (Len: 8)),
(fc: (Frequency: 67); dl: (Len: 8)), (fc: (Frequency: 195); dl: (Len: 8)), (fc: (Frequency: 35); dl: (Len: 8)),
(fc: (Frequency: 163); dl: (Len: 8)), (fc: (Frequency: 99); dl: (Len: 8)), (fc: (Frequency: 227); dl: (Len: 8))
);
// The static distance tree. (Actually a trivial tree since all lens use 5 Bits.)
StaticDescriptorTree: array[0..D_CODES - 1] of TTreeEntry = (
(fc: (Frequency: 0); dl: (Len: 5)), (fc: (Frequency: 16); dl: (Len: 5)), (fc: (Frequency: 8); dl: (Len: 5)),
(fc: (Frequency: 24); dl: (Len: 5)), (fc: (Frequency: 4); dl: (Len: 5)), (fc: (Frequency: 20); dl: (Len: 5)),
(fc: (Frequency: 12); dl: (Len: 5)), (fc: (Frequency: 28); dl: (Len: 5)), (fc: (Frequency: 2); dl: (Len: 5)),
(fc: (Frequency: 18); dl: (Len: 5)), (fc: (Frequency: 10); dl: (Len: 5)), (fc: (Frequency: 26); dl: (Len: 5)),
(fc: (Frequency: 6); dl: (Len: 5)), (fc: (Frequency: 22); dl: (Len: 5)), (fc: (Frequency: 14); dl: (Len: 5)),
(fc: (Frequency: 30); dl: (Len: 5)), (fc: (Frequency: 1); dl: (Len: 5)), (fc: (Frequency: 17); dl: (Len: 5)),
(fc: (Frequency: 9); dl: (Len: 5)), (fc: (Frequency: 25); dl: (Len: 5)), (fc: (Frequency: 5); dl: (Len: 5)),
(fc: (Frequency: 21); dl: (Len: 5)), (fc: (Frequency: 13); dl: (Len: 5)), (fc: (Frequency: 29); dl: (Len: 5)),
(fc: (Frequency: 3); dl: (Len: 5)), (fc: (Frequency: 19); dl: (Len: 5)), (fc: (Frequency: 11); dl: (Len: 5)),
(fc: (Frequency: 27); dl: (Len: 5)), (fc: (Frequency: 7); dl: (Len: 5)), (fc: (Frequency: 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.
DistanceCode: array[0..DIST_CODE_LEN - 1] of Byte = (
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)
LengthCode: array[0..MAX_MATCH - MIN_MATCH] of Byte = (
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)
BaseLength: array[0..LENGTH_CODES - 1] of byte = (
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)
BaseDistance: array[0..D_CODES - 1] of Integer = (
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
);
MIN_LOOKAHEAD = (MAX_MATCH + MIN_MATCH + 1);
MAX_BL_BITS = 7; // bit length codes must not exceed MAX_BL_BITS bits
END_BLOCK = 256; // end of block literal code
REP_3_6 = 16; // repeat previous bit length 3-6 times (2 Bits of repeat count)
REPZ_3_10 = 17; // repeat a zero length 3-10 times (3 Bits of repeat count)
REPZ_11_138 = 18; // repeat a zero length 11-138 times (7 Bits of repeat count)
// extra bits for each length code
ExtraLengthBits: array[0..LENGTH_CODES - 1] of Integer = (
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
);
// extra bits for each distance code
ExtraDistanceBits: array[0..D_CODES - 1] of Integer = (
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
);
// extra bits for each bit length code
ExtraBitLengthBits: array[0..BL_CODES - 1] of Integer = (
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7
);
// The lengths of the bit length codes are sent in order of decreasing probability,
// to avoid transmitting the lengths for unused bit length codes.
BitLengthOrder: array[0..BL_CODES - 1] of Byte = (
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
);
// Number of bits used within BitsBuffer. (BitsBuffer might be implemented on more than 16 bits on some systems.)
BufferSize = 16;
StaticLiteralDescriptor: TStaticTreeDescriptor = (
StaticTree: @StaticLiteralTree; // pointer to array of TTreeEntry
ExtraBits: @ExtraLengthBits; // pointer to array of integer
ExtraBase: LITERALS + 1;
Elements: L_CODES;
MaxLength: MAX_BITS
);
StaticDistanceDescriptor: TStaticTreeDescriptor = (
StaticTree: @StaticDescriptorTree;
ExtraBits: @ExtraDistanceBits;
ExtraBase: 0;
Elements: D_CODES;
MaxLength: MAX_BITS
);
StaticBitLengthDescriptor: TStaticTreeDescriptor = (
StaticTree: nil;
ExtraBits: @ExtraBitLengthBits;
ExtraBase: 0;
Elements: BL_CODES;
MaxLength: MAX_BL_BITS
);
//----------------- Inflate support
const
InflateMask: array[0..16] of Cardinal = ($0000, $0001, $0003, $0007, $000F,
$001F, $003F, $007F, $00FF, $01FF, $03FF, $07FF, $0FFF, $1FFF, $3FFF, $7FFF, $FFFF);
function InflateFlush(var S: TInflateBlocksState; var Z: TZState; R: Integer): Integer;
// copies as much as possible from the sliding window to the output area
var
N: Cardinal;
P: PByte;
Q: PByte;
begin
// local copies of source and destination pointers
P := Z.NextOutput;
Q := S.Read;
// compute number of bytes to copy as far as end of window
if PtrUInt(Q) <= PtrUInt(S.Write) then
N := PtrUInt(S.Write) - PtrUInt(Q)
else
N := PtrUInt(S.zend) - PtrUInt(Q);
if N > Z.AvailableOutput then
N := Z.AvailableOutput;
if (N <> 0) and (R = Z_BUF_ERROR) then
R := Z_OK;
// update counters
Dec(Z.AvailableOutput, N);
Inc(Z.TotalOutput, N);
// copy as far as end of Window
Move(Q^, P^, 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 := PtrUInt(S.write) - PtrUInt(Q);
if N > Z.AvailableOutput then
N := Z.AvailableOutput;
if (N <> 0) and (R = Z_BUF_ERROR) then
R := Z_OK;
// update counters
Dec(Z.AvailableOutput, N);
Inc(Z.TotalOutput, N);
// copy
Move(Q^, P^, N);
Inc(P, N);
Inc(Q, N);
end;
// update pointers
Z.NextOutput := P;
S.Read := Q;
Result := R;
end;
function InflateFast(LiteralBits, DistanceBits: Cardinal; TL, TD: PInflateHuft;
var S: TInflateBlocksState; var Z: TZState): Integer;
// Called with number of bytes left to write in window at least 258 (the maximum string 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.
var
Temp: PInflateHuft;
Extra: Cardinal; // extra bits or operation
BitsBuffer: Cardinal;
K: Cardinal; // bits in bit buffer
P: PByte; // input data pointer
N: Cardinal; // bytes available there