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{ Copyright (C) <2005> <Andrew Haines> chmbase.pas
This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This program 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 Library General Public License
for more details.
You should have received a copy of the GNU Library General Public License
along with this library; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
}
{
See the file COPYING.FPC, included in this distribution,
for details about the copyright.
}
unit chmbase;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils;
const
CHMPackageVersion = '3.0.0'; // to be put in readme
type
{$PACKRECORDS C}
TITSFHeader= record
ITSFsig: array [0..3] of char;
Version: LongWord;
HeaderLength: LongWord;
Unknown_1: LongWord;
TimeStamp: LongWord; //bigendian
LanguageID: LongWord;
end;
TITSFHeaderEntry = record
PosFromZero: QWord;
Length: QWord;
end;
//Version 3 has this qword. 2 does not
TITSFHeaderSuffix = record
Offset: QWord; // offset within file of content section 0
end;
TITSPHeaderPrefix = record
Unknown1: LongWord;// = $01FE
Unknown2: LongWord;// = 0
FileSize: QWord;
Unknown3: LongWord;// =0
Unknown4: LongWord;// =0
end;
TITSPHeader = record
ITSPsig: array [0..3] of char; // = 'ITSP'
Version: LongWord; // =1
DirHeaderLength: Longword; // Length of the directory header
Unknown1: LongWord; // =$0a
ChunkSize: LongWord; // $1000
Density: LongWord; // usually = 2
IndexTreeDepth: LongWord;// 1 if there is no index 2 if there is one level of PMGI chunks
IndexOfRootChunk: LongInt;// -1 if no root chunk
FirstPMGLChunkIndex,
LastPMGLChunkIndex: LongWord;
Unknown2: LongInt; // = -1
DirectoryChunkCount: LongWord;
LanguageID: LongWord;
GUID: TGuid;
LengthAgain: LongWord; //??? $54
Unknown3: LongInt; // = -1
Unknown4: LongInt; // = -1
Unknown5: LongInt; // = -1
end;
TDirChunkType = (ctPMGL, ctPMGI, ctAOLL, ctAOLI, ctUnknown);
TPMGListChunk = record
PMGLsig: array [0..3] of char;
UnusedSpace: Longword; ///!!! this value can also represent the size of quickref area in the end of the chunk
Unknown1: Longword; //always 0
PreviousChunkIndex: LongInt; // chunk number of the prev listing chunk when reading dir in sequence
// (-1 if this is the first listing chunk)
NextChunkIndex: LongInt; // chunk number of the next listing chunk (-1 if this is the last chunk)
end;
PPMGListChunkEntry = ^TPMGListChunkEntry;
TPMGListChunkEntry = record
//NameLength: LongInt; we don't need this permanantly so I've moved it to a temp var
Name: String;
ContentSection: LongWord;//QWord;
ContentOffset: QWord;
DecompressedLength: QWord;
end;
TPMGIIndexChunk = record
PMGIsig: array [0..3] of char;
UnusedSpace: LongWord; // has a quickref area
end;
TPMGIIndexChunkEntry = record
Name: String;
ListingChunk: DWord;
end;
const
ITSFHeaderGUID : TGuid = '{7C01FD10-7BAA-11D0-9E0C-00A0C922E6EC}';
ITSFFileSig: array [0..3] of char = 'ITSF';
ITSPHeaderGUID : TGuid = '{5D02926A-212E-11D0-9DF9-00A0C922E6EC}';
ITSPHeaderSig: array [0..3] of char = 'ITSP';
// this function will advance the stream to the end of the compressed integer
// and return the value
function GetCompressedInteger(const Stream: TStream): DWord;
// returns the number of bytes written to the stream
function WriteCompressedInteger(const Stream: TStream; ANumber: DWord): DWord;
function WriteCompressedInteger(Buffer: Pointer; ANumber: DWord): DWord;
// stupid needed function
function ChmCompareText(S1, S2: String): Integer; inline;
implementation
function GetCompressedInteger(const Stream: TStream): DWord;
var
total: QWord = 0;
temp: Byte;
Sanity: Integer = 0;
begin
try
temp := Stream.ReadByte;
while temp >= $80 do begin
total := total shl 7;
total := total + temp and $7f;
temp := Stream.ReadByte;
Inc(Sanity);
if Sanity > 8 then begin
Result := 0;
Exit;
end;
end;
Result := (total shl 7) + temp;
except
Result := 0;
end;
end;
// returns how many bytes were written
function WriteCompressedInteger(const Stream: TStream; ANumber: DWord): DWord;
var
Buffer: QWord; // Easily large enough
begin
Result := WriteCompressedInteger(@Buffer, ANumber);
Result := Stream.Write(Buffer, Result);
end;
// returns how many bytes were written
function WriteCompressedInteger(Buffer: Pointer; ANumber: DWord): DWord;
var
bit: dword;
mask: QWord;
buf: PByte;
Value: QWord = 0;
TheEnd: DWord = 0;
begin
bit := 28; //((sizeof(dWord)*8)div 7)*7; // = 28
buf := @Value;
{$push}
{$R-}
while True do begin
mask := $7f shl bit;
if (bit = 0) or ((ANumber and mask)<>0) then break;
Dec(bit, 7);
end;
while True do begin
buf^ := Byte(((ANumber shr bit)and $7f));
if(bit = 0) then break;
buf^ := buf^ or $80;
Inc(buf);
Dec(bit, 7);
Inc(TheEnd);
end;
{$pop}
buf := @Value;
Result := TheEnd+1;
Move(Value, Buffer^, Result);
{$ifdef chm_debug}
if Result > 8 then WriteLn(' ', ANumber,' WRITE_COMPRESSED_INTEGER too big!: ', Result, ' ');
{$endif}
end;
function ChmCompareText(S1, S2: String): Integer; inline;
begin
// for our purposes the CompareText function will not work.
Result := CompareStr(LowerCase(S1), Lowercase(S2));
end;
end.
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