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https://github.com/moparisthebest/Simba
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679 lines
16 KiB
ObjectPascal
679 lines
16 KiB
ObjectPascal
unit bzip2;
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{****************************************************************************
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BZIP2 decompression unit
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Copyright (C) 2002 by Daniel Mantione
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This unit provides a decompression stream to decode .bz2 files. It is
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inpired by Julian R. Seward's libbzip2 library and therefore you should
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send credits to him and bug reports to me :)
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This code is licensed under the same terms as the original libbz2 library,
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which is decsribed in the file LICENSE. If you don't have this file, look
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at http://www.freepascal.org for this bzip2 unit, the LICENSE file will
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be included. In case of problems, contact the author.
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E-mail addresses:
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Daniel Mantione <daniel.mantione@freepascal.org>
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Julian R. Seward <jseward@acm.org>
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Please do not contact Julian about this Pascal library, he didn't wrote it.
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****************************************************************************}
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interface
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{$goto on}
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uses objects, bzip2comn,classes;
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Type
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pstream = ^classes.tstream;
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Tbzip2_decode_stream=object(objects.Tstream)
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short:cardinal;
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readstream:pstream;
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block_randomized:boolean;
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blocksize:byte;
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tt:Pcardinal_array;
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tt_count:cardinal;
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rle_run_left,rle_run_data:byte;
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nextrle:Pbyte;
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decode_available:cardinal;
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block_origin:cardinal;
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current_block:cardinal;
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read_data,bits_available:byte;
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inuse16:set of 0..15;
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inuse:set of 0..255;
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inuse_count:cardinal;
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seq_to_unseq:array[0..255] of byte;
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alphasize:cardinal;
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group_count,group_pos,gsel,gminlen:byte;
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group_no:cardinal;
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glimit,gperm,gbase:Phuffarray;
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selector_count:cardinal;
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selector,selector_mtf:array[0..max_selectors] of byte;
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len:array[0..max_groups,0..max_alpha_size] of byte;
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limit:array[0..max_groups,0..max_alpha_size] of cardinal;
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base:array[0..max_groups,0..max_alpha_size] of cardinal;
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perm:array[0..max_groups,0..max_alpha_size] of cardinal;
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minlens:array[0..max_groups] of byte;
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cftab:array[0..257] of cardinal;
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mtfbase:array[0..256 div mtfl_size-1] of cardinal;
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mtfa:array[0..mtfa_size-1] of byte;
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constructor init(Areadstream:pstream);
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function get_bits(n:byte):byte;
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function get_boolean:boolean;
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function get_byte:byte;
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function get_cardinal24:cardinal;
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function get_cardinal:cardinal;
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procedure receive_mapping_table;
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procedure receive_selectors;
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procedure undo_mtf_values;
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procedure receive_coding_tables;
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procedure make_hufftab;
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procedure init_mtf;
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function get_mtf_value:cardinal;
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procedure move_mtf_block;
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procedure receive_mtf_values;
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procedure detransform;
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function decode_block:boolean;
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procedure read(var buf;count:Longint);virtual;
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procedure new_block;
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procedure consume_rle;inline;
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procedure rle_read(bufptr:Pbyte;var count:Longint);
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destructor done;virtual;
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end;
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implementation
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{$ifdef i386}
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{$i bzip2i386.inc}
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{$endif}
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{*****************************************************************************
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Tbzip2_decode_stream
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*****************************************************************************}
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constructor Tbzip2_decode_stream.init(Areadstream:pstream);
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var magic:array[1..3] of char;
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c:char;
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begin
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readstream:=Areadstream;
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{Read the magic.}
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readstream^.read(magic,sizeof(magic));
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if magic<>bzip2_stream_magic then
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begin
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error(stiniterror,bzip2_bad_header_magic);
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exit;
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end;
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{Read the block size and allocate the working array.}
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readstream^.read(c,1);
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blocksize:=byte(c)-byte('0');
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getmem(tt,blocksize*100000*sizeof(cardinal));
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decode_available:=high(decode_available);
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end;
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function Tbzip2_decode_stream.get_bits(n:byte):byte;
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var data:byte;
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begin
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if n>bits_available then
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begin
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readstream^.read(data,1);
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get_bits:=(read_data shr (8-n)) or data shr (8-(n-bits_available));
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read_data:=data shl (n-bits_available);
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inc(bits_available,8);
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end
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else
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begin
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get_bits:=read_data shr (8-n);
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read_data:=read_data shl n;
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end;
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dec(bits_available,n);
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end;
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function Tbzip2_decode_stream.get_boolean:boolean;
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begin
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get_boolean:=boolean(get_bits(1));
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end;
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function Tbzip2_decode_stream.get_byte:byte;
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begin
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get_byte:=get_bits(8);
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end;
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function Tbzip2_decode_stream.get_cardinal24:cardinal;
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begin
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get_cardinal24:=get_bits(8) shl 16 or get_bits(8) shl 8 or get_bits(8);
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end;
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function Tbzip2_decode_stream.get_cardinal:cardinal;
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begin
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get_cardinal:=get_bits(8) shl 24 or get_bits(8) shl 16 or get_bits(8) shl 8 or
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get_bits(8);
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end;
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procedure Tbzip2_decode_stream.receive_mapping_table;
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{Receive the mapping table. To save space, the inuse set is stored in pieces
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of 16 bits. First 16 bits are stored which pieces of 16 bits are used, then
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the pieces follow.}
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var i,j:byte;
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begin
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inuse16:=[];
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{Receive the first 16 bits which tell which pieces are stored.}
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for i:=0 to 15 do
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if get_boolean then
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include(inuse16,i);
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{Receive the used pieces.}
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inuse:=[];
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inuse_count:=0;
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for i:=0 to 15 do
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if i in inuse16 then
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for j:=0 to 15 do
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if get_boolean then
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begin
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include(inuse,16*i+j);
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seq_to_unseq[inuse_count]:=16*i+j;
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inc(inuse_count);
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end;
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{ system.write('Mapping table: ');
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for i:=0 to 255 do
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if i in inuse then
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system.write(i,' ');
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writeln;}
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end;
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procedure Tbzip2_decode_stream.receive_selectors;
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{Receives the selectors.}
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var i:cardinal;
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j:byte;
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begin
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group_count:=get_bits(3);
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selector_count:=get_bits(8) shl 7 or get_bits(7);
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for i:=0 to selector_count-1 do
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begin
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j:=0;
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while get_boolean do
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begin
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inc(j);
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if j>5 then
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error(streaderror,bzip2_data_error);
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end;
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selector_mtf[i]:=j;
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end;
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{ system.write('Selector_mtf: ');
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for i:=0 to selector_count-1 do
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system.write(selector_mtf[i],' ');
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writeln;}
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end;
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procedure Tbzip2_decode_stream.undo_mtf_values;
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{Undo the MTF values for the selectors.}
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var pos:array[0..max_groups] of byte;
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i:cardinal;
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v,tmp:byte;
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begin
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for v:=0 to group_count-1 do
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pos[v]:=v;
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for i:=0 to selector_count-1 do
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begin
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v:=selector_mtf[i];
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tmp:=pos[v];
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while v<>0 do
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begin
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pos[v]:=pos[v-1];
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dec(v);
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end;
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pos[0]:=tmp;
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selector[i]:=tmp;
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end;
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end;
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procedure Tbzip2_decode_stream.receive_coding_tables;
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var t,curr:byte;
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i:cardinal;
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begin
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for t:=0 to group_count-1 do
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begin
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curr:=get_bits(5);
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for i:=0 to alphasize-1 do
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begin
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repeat
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if not(curr in [1..20]) then
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begin
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error(streaderror,bzip2_data_error);
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exit;
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end;
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if not get_boolean then
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break;
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if get_boolean then
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dec(curr)
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else
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inc(curr);
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until false;
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len[t,i]:=curr;
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end;
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end;
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{ writeln('Coding tables:');
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for t:=0 to group_count-1 do
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begin
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for i:=0 to alphasize-1 do
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system.write(len[t,i],' ');
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writeln;
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end;}
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end;
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procedure Tbzip2_decode_stream.make_hufftab;
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{Builds the Huffman tables.}
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var i:cardinal;
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t,minlen,maxlen:byte;
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begin
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for t:=0 to group_count-1 do
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begin
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minlen:=32;
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maxlen:=0;
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for i:=0 to alphasize-1 do
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begin
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if len[t,i]>maxlen then
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maxlen:=len[t,i];
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if len[t,i]<minlen then
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minlen:=len[t,i];
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end;
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hb_create_decode_tables(limit[t],base[t],perm[t],len[t],
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minlen,maxlen,alphasize);
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minlens[t]:=minlen;
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end;
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end;
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procedure Tbzip2_decode_stream.init_mtf;
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var i,j:byte;
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k:cardinal;
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begin
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k:=mtfa_size-1;
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for i:=256 div mtfl_size-1 downto 0 do
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begin
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for j:=mtfl_size-1 downto 0 do
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begin
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mtfa[k]:=i*mtfl_size+j;
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dec(k);
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end;
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mtfbase[i]:=k+1;
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end;
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end;
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function Tbzip2_decode_stream.get_mtf_value:cardinal;
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var zn:byte;
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zvec:cardinal;
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begin
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if group_pos=0 then
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begin
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inc(group_no);
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group_pos:=group_size;
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gsel:=selector[group_no];
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gminlen:=minlens[gsel];
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glimit:=@limit[gsel];
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gperm:=@perm[gsel];
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gbase:=@base[gsel];
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end;
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dec(group_pos);
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zn:=gminlen;
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zvec:=get_bits(zn);
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while zvec>glimit^[zn] do
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begin
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inc(zn);
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zvec:=zvec shl 1 or byte(get_boolean);
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end;
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get_mtf_value:=gperm^[zvec-gbase^[zn]];
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end;
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procedure Tbzip2_decode_stream.move_mtf_block;
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var i:byte;
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j,k:cardinal;
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begin
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k:=MTFA_SIZE;
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for i:=256 div MTFL_SIZE-1 downto 0 do
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begin
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j:=mtfbase[i];
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Pcardinal(@mtfa[k- 4])^:=Pcardinal(@mtfa[j+12])^;
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Pcardinal(@mtfa[k- 8])^:=Pcardinal(@mtfa[j+ 8])^;
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Pcardinal(@mtfa[k-12])^:=Pcardinal(@mtfa[j+ 4])^;
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dec(k,16);
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Pcardinal(@mtfa[k ])^:=Pcardinal(@mtfa[j ])^;
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mtfbase[i]:=k;
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end;
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end;
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procedure Tbzip2_decode_stream.receive_mtf_values;
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const run_a=0;
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run_b=1;
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var t,next_sym:cardinal;
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es:cardinal;
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n:byte;
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nn,i:cardinal;
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p,q:Pbyte;
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u,v:Pcardinal;
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lno,off:cardinal;
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begin
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group_no:=high(group_no);
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group_pos:=0;
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t:=0;
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for i:=0 to 257 do
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cftab[i]:=0;
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init_mtf;
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next_sym:=get_mtf_value;
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while next_sym<>inuse_count+1 do
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begin
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{ writeln(t,' ',next_sym);
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if t=22296 then
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t:=t; }
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if next_sym<=run_b then
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begin
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es:=0;
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n:=0;
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repeat
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inc(es,(next_sym+1) shl n);
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inc(n);
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next_sym:=get_mtf_value;
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until next_sym>run_b;
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n:=seq_to_unseq[mtfa[mtfbase[0]]];
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inc(cftab[n],es);
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if t+es>100000*blocksize then
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begin
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error(streaderror,bzip2_data_error);
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exit;
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end;
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while es>0 do
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begin
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tt^[t]:=n;
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dec(es);
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inc(t);
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end;
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end
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else
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begin
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nn:=next_sym-1;
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if nn<mtfl_size then
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begin
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{Avoid the costs of the general case.}
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p:=@mtfa[mtfbase[0]];
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q:=p+nn;
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n:=q^;
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repeat
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q^:=(q-1)^;
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dec(q);
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until q=p;
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q^:=n;
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end
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else
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begin
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{General case.}
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lno:=nn div MTFL_SIZE;
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off:=nn and (MTFL_SIZE-1);
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p:=@mtfa[mtfbase[lno]];
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q:=p+off;
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n:=q^;
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while(q<>p) do
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begin
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q^:=(q-1)^;
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dec(q);
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end;
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u:=@mtfbase;
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v:=u+lno;
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repeat
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mtfa[v^]:=mtfa[(v-1)^+MTFL_SIZE-1];
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dec(v);
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dec(v^);
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until v=u;
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mtfa[v^]:=n;
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if v^=0 then
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move_mtf_block;
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end;
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inc(cftab[seq_to_unseq[n]]);
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tt^[t]:=cardinal(seq_to_unseq[n]);
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inc(t);
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if t>100000*blocksize then
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begin
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error(streaderror,bzip2_data_error);
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exit;
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end;
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next_sym:=get_mtf_value;
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end;
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end;
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tt_count:=t;
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{Setup cftab to facilitate generation of T^(-1).}
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t:=0;
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for i:=0 to 256 do
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begin
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nn:=cftab[i];
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cftab[i]:=t;
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{ writeln(i,' ',t);}
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inc(t,nn);
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end;
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end;
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{$ifndef HAVE_DETRANSFORM}
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procedure Tbzip2_decode_stream.detransform;
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var a:cardinal;
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p,q,r:Pcardinal;
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begin
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a:=0;
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p:=@tt^[0];
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q:=p+tt_count;
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while p<>q do
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begin
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r:=@tt^[cftab[p^ and $ff]];
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inc(cftab[p^ and $ff]);
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r^:=r^ or a;
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inc(a,256);
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inc(p);
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end;
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end;
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{$endif}
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function Tbzip2_decode_stream.decode_block:boolean;
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{Decode a new compressed block.}
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var magic:array[1..6] of char;
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stored_blockcrc:cardinal;
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i:byte;
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begin
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for i:=1 to 6 do
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magic[i]:=char(get_byte);
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if magic='1AY&SY' then
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begin
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inc(current_block);
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{ writeln('Block ',current_block,': Header ok');}
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stored_blockcrc:=get_cardinal;
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block_randomized:=get_boolean;
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block_origin:=get_cardinal24;
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{Receive the mapping table.}
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receive_mapping_table;
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alphasize:=cardinal(inuse_count)+2;
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{ writeln('Mapping table ok.');}
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{Receive the selectors.}
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receive_selectors;
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if status<>0 then
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exit;
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{ writeln('Selectors ok.');}
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{Undo the MTF values for the selectors.}
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undo_mtf_values;
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{ writeln('Undo mtf ok.');}
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{Receive the coding tables.}
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receive_coding_tables;
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if status<>0 then
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exit;
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{ writeln('Coding tables ok');}
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{Build the Huffman tables.}
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make_hufftab;
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{ writeln('Huffman ok.');}
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{Receive the MTF values.}
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receive_mtf_values;
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{ writeln('MTF OK');}
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{Undo the Burrows Wheeler transformation.}
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detransform;
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{ writeln('Detransform OK');}
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decode_available:=tt_count;
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end
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else
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begin
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if magic<>#$17'rE8P'#$90 then
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error(streaderror,bzip2_bad_block_magic);
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decode_block:=false;
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end;
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end;
|
|
|
|
procedure Tbzip2_decode_stream.new_block;
|
|
|
|
begin
|
|
if decode_block then
|
|
nextrle:=@tt^[tt^[block_origin] shr 8]
|
|
else
|
|
begin
|
|
error(streaderror,bzip2_endoffile);
|
|
nextrle:=nil;
|
|
end;
|
|
end;
|
|
|
|
procedure Tbzip2_decode_stream.consume_rle;inline;
|
|
|
|
{Make nextrle point to the next decoded byte. If nextrle did point to the last
|
|
byte in the current block, decode the next block.}
|
|
|
|
begin
|
|
{ Pcardinal(nextrle)^:=Pcardinal(nextrle)^ shr 8;}
|
|
nextrle:=@tt^[Pcardinal(nextrle)^ shr 8];
|
|
dec(decode_available);
|
|
if decode_available=0 then
|
|
new_block;
|
|
end;
|
|
|
|
procedure Tbzip2_decode_stream.rle_read(bufptr:Pbyte;var count:Longint);
|
|
|
|
var rle_len:cardinal;
|
|
data:byte;
|
|
|
|
label rle_write;
|
|
|
|
begin
|
|
rle_len:=rle_run_left;
|
|
data:=rle_run_data;
|
|
if block_randomized then
|
|
{Not yet implemented.}
|
|
runerror(212)
|
|
else
|
|
begin
|
|
if rle_len<>0 then
|
|
{Speed is important. Instead of an if statement within the
|
|
repeat loop use a goto outside the loop.}
|
|
goto rle_write;
|
|
repeat
|
|
if decode_available=0 then
|
|
break;
|
|
rle_len:=1;
|
|
data:=nextrle^;
|
|
consume_rle;
|
|
if (decode_available>0) and (data=nextrle^) then
|
|
begin
|
|
inc(rle_len);
|
|
consume_rle;
|
|
if (decode_available>0) and (data=nextrle^) then
|
|
begin
|
|
inc(rle_len);
|
|
consume_rle;
|
|
if (decode_available>0) and (data=nextrle^) then
|
|
begin
|
|
consume_rle;
|
|
inc(rle_len,nextrle^+1);
|
|
consume_rle;
|
|
end;
|
|
end;
|
|
end;
|
|
rle_write:
|
|
repeat
|
|
bufptr^:=data;
|
|
inc(bufptr);
|
|
dec(count);
|
|
dec(rle_len);
|
|
until (rle_len=0) or (count=0);
|
|
until count=0;
|
|
short:=count;
|
|
end;
|
|
rle_run_data:=data;
|
|
rle_run_left:=rle_len;
|
|
end;
|
|
|
|
procedure Tbzip2_decode_stream.read(var buf;count:Longint);
|
|
|
|
var bufptr:Pbyte;
|
|
|
|
begin
|
|
short:=0;
|
|
bufptr:=@buf;
|
|
if decode_available=high(decode_available) then
|
|
begin
|
|
{Initialize the rle process:
|
|
- Decode a block
|
|
- Initialize pointer.}
|
|
if not decode_block then
|
|
begin
|
|
error(streaderror,bzip2_endoffile);
|
|
nextrle:=nil;
|
|
end;
|
|
nextrle:=@tt^[tt^[block_origin] shr 8];
|
|
end;
|
|
rle_read(bufptr,count);
|
|
end;
|
|
|
|
destructor Tbzip2_decode_stream.done;
|
|
|
|
begin
|
|
if tt<>nil then
|
|
freemem(tt,blocksize*100000*sizeof(cardinal));
|
|
inherited done;
|
|
end;
|
|
|
|
end.
|