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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) 2015 Arnaud Bouchez
Synopse Informatique - http://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
------------------------------------------------------------------------
compression stuff compatible with LZ77 Deflate/Inflate
Improvements by A.Bouchez on 2006-2010 - http://bouchez.info
- CRC32 table can be generated by code (safe 1KB in executable)
- Inflate made 50% faster than MadLib's original by tuned Move() usage
and some critical part rewrite
- included .zip archive reading from file, resource or direct memory
- included .zip archive write into a file (new .zip creation, not update)
}
{$WARNINGS OFF}
{$Q-,R-} // Turn range checking and overflow checking off
{ $D-,L-}
interface
uses
{$ifdef WIN32}
Windows,
{$else}
LibC, Types,
{$endif}
SysUtils;
/// 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
function CompressString(const data: string; failIfGrow: boolean = false) : string;
/// uncompress memory using the ZLib INFLATE algorithm
function UncompressString(const data: string) : string;
{$ifdef WIN32} { use Windows MapFile }
function CompressFile(const srcFile, dstFile: string; failIfGrow: boolean = false) : boolean;
function UncompressFile(const srcFile, dstFile: string; lastWriteTime: int64 = 0; attr: dword = 0) : boolean;
function GetCompressedFileInfo (const comprFile: string; var size: int64; var crc32: dword) : boolean;
function GetUncompressedFileInfo (const uncomprFile: string; var size: int64; var crc32: dword) : boolean;
function IsCompressedFileEqual (const uncomprFile, comprFile: string) : boolean;
{{ You can create a "zip" compatible archive by calling the "Zip" function.
The first parameter is the full file path of the new zip archive.
The second parameter must be an array of the files you want to have zipped
into the archive (full file path again, please).
The third array (only file names, please) allows you to store the files into
the zip under a different name.
Generally the resulting zip archive should not contain any directory structure:
all zipped files are directly stored in the archive's root, if NoSubDirectories
is set to TRUE. }
function Zip(const zip: string; const files, zipAs: array of string; NoSubDirectories: boolean=false) : boolean;
{$endif}
/// create a void .zip file
procedure CreateVoidZip(const aFileName: string);
/// create a compatible .gz file (returns file size)
function GzCompress(src: pointer; srcLen: integer; const fName: string): cardinal;
/// calculate the CRC32 hash of a specified memory buffer
function UpdateCrc32(acrc32: cardinal; inBuf: pointer; inLen: integer) : cardinal;
{$DEFINE DYNAMIC_CRC_TABLE}
{ if defined, the crc32Tab[] is created on staturp: save 1KB of code size }
/// the static buffer used for fast CRC32 hashing
{$ifdef DYNAMIC_CRC_TABLE}
var
crc32Tab : array [0..255] of cardinal;
{$else}
const
crc32Tab : array [0..255] of cardinal =
($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}
type
PFileInfo = ^TFileInfo;
{{ 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;
{{ 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; // $06054b50
thisDisk : word; // 0
headerDisk : word; // 0
thisFiles : word; // 1
totalFiles : word; // 1
headerSize : dword; // sizeOf(TFileHeaders + names)
headerOffset : dword; // @TFileHeader
commentLen : word; // 0
end;
{$ifdef WIN32}
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..127-8] 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;
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 aName: AnsiString): integer;
/// uncompress a file stored inside the .zip archive into a destination folder
function UnZipFile(aIndex: integer; DestPath: string; ForceWriteFlush: boolean): boolean;
/// uncompress a file stored inside the .zip archive into memory
function UnZip(aIndex: integer): string; 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: string): boolean;
/// get any initial .exe file
function GetInitialExeContent: ansistring;
/// 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;
{$endif}
/// 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: AnsiString;
/// 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 aFileName: AnsiString; 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: AnsiString; 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 aFileName: AnsiString; 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: AnsiString);
/// release associated memory, and close destination file
destructor Destroy; override;
end;
implementation
procedure MoveWithOverlap(Src: PByte; Dst: PByte; Count: Integer);
// special tuned Move() routine, including data overlap bug correction
{$ifdef PUREPASCAL}
var i: integer;
begin // should be fast enough in practice
for i := 1 to Count do begin
Dst^ := Src^;
inc(Dst);
inc(Src);
end;
end;
{$else}
asm // eax=source edx=dest ecx=count
push edx
sub edx,eax
cmp edx,ecx // avoid move error if dest and source overlaps
pop edx // restore original edx=dest
ja System.Move // call FastMove() routine for normal code
or ecx,ecx
jz @@Exit
push edi
mov edi,edx // restore original edi=dest
@@overlap: // byte by byte slower but accurate move routine
mov dl,[eax]
inc eax
mov [edi],dl
inc edi
dec ecx
jnz @@overlap
pop edi
@@Exit:
end;
{$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 = 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;
THuftField = array[0..(MaxInt div SizeOf(TInflateHuft)) - 1] of TInflateHuft;
PHuftField = ^THuftField;
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 Cardinal(Q) <= Cardinal(S.Write) then N := Cardinal(S.Write) - Cardinal(Q)
else N := Cardinal(S.zend) - Cardinal(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 := Cardinal(S.write) - Cardinal(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
Q: PByte; // output window write pointer
M: Cardinal; // bytes to end of window or read pointer
ml: Cardinal; // mask for literal/length tree
md: Cardinal; // mask for distance tree
C: Cardinal; // bytes to copy
D: Cardinal; // distance back to copy from
R: PByte; // copy source pointer
begin
// load input, output, bit values
P := Z.NextInput;
N := Z.AvailableInput;
BitsBuffer := S.bitb;
K := S.bitk;
Q := S.write;
if Cardinal(Q) < Cardinal(S.Read) then M := Cardinal(S.read) - Cardinal(Q) - 1
else M := Cardinal(S.zend)-Cardinal(Q);
// initialize masks
ml := InflateMask[LiteralBits];
md := InflateMask[DistanceBits];
// do until not enough input or output space for fast loop,
// assume called with (M >= 258) and (N >= 10)
repeat
// get literal/length Code
while K < 20 do begin
Dec(N);
BitsBuffer := BitsBuffer or (Cardinal(P^) shl K);
Inc(K, 8);
Inc(P);
end;
Temp := @PHuftField(TL)[BitsBuffer and ml];
Extra := Temp.exop;
if Extra = 0 then begin
BitsBuffer := BitsBuffer shr Temp.Bits;
Dec(K, Temp.Bits);
Q^ := Temp.Base;
Inc(Q);
Dec(M);