* src/lzw/ftlzw2.c, src/lzw/ftzopen.h, src/lzw/ftzopen.c, src/lzw/rules.mk:
first version of LZW loader re-implementation. Apparently, saves about
260 KB of heap memory when loading tir24.pcf.Z
david-pic-changes
David Turner
20 years ago
parent
7e30776ee8
commit
c1b6d08291
6 changed files with 1009 additions and 24 deletions
@ -0,0 +1,411 @@ |
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/***************************************************************************/ |
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/* */ |
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/* ftlzw.c */ |
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/* */ |
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/* FreeType support for .Z compressed files. */ |
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/* */ |
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/* This optional component relies on NetBSD's zopen(). It should mainly */ |
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/* be used to parse compressed PCF fonts, as found with many X11 server */ |
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/* distributions. */ |
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/* */ |
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/* Copyright 2004, 2005 by */ |
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/* Albert Chin-A-Young. */ |
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/* */ |
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/* Based on code in src/gzip/ftgzip.c, Copyright 2004 by */ |
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */ |
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/* */ |
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/* This file is part of the FreeType project, and may only be used, */ |
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/* modified, and distributed under the terms of the FreeType project */ |
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
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/* this file you indicate that you have read the license and */ |
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/* understand and accept it fully. */ |
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/* */ |
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/***************************************************************************/ |
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|
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#include <ft2build.h> |
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#include FT_INTERNAL_MEMORY_H |
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#include FT_INTERNAL_STREAM_H |
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#include FT_INTERNAL_DEBUG_H |
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#include <string.h> |
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#include <stdio.h> |
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#include FT_MODULE_ERRORS_H |
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#undef __FTERRORS_H__ |
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#define FT_ERR_PREFIX LZW_Err_ |
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#define FT_ERR_BASE FT_Mod_Err_LZW |
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#include FT_ERRORS_H |
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#ifdef FT_CONFIG_OPTION_USE_LZW |
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#include "ftzopen.h" |
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/***************************************************************************/ |
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/***************************************************************************/ |
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/***** *****/ |
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/***** M E M O R Y M A N A G E M E N T *****/ |
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/***** *****/ |
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/***************************************************************************/ |
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/***************************************************************************/ |
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/***************************************************************************/ |
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/***************************************************************************/ |
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/***** *****/ |
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/***** F I L E D E S C R I P T O R *****/ |
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/***** *****/ |
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/***************************************************************************/ |
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/***************************************************************************/ |
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#define FT_LZW_BUFFER_SIZE 4096 |
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typedef struct FT_LZWFileRec_ |
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{ |
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FT_Stream source; /* parent/source stream */ |
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FT_Stream stream; /* embedding stream */ |
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FT_Memory memory; /* memory allocator */ |
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FT_LzwStateRec lzw; /* lzw decompressor state */ |
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|
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FT_Byte buffer[ FT_LZW_BUFFER_SIZE ]; /* output buffer */ |
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FT_ULong pos; /* position in output */ |
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FT_Byte* cursor; |
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FT_Byte* limit; |
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} FT_LZWFileRec, *FT_LZWFile; |
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/* check and skip .Z header */ |
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static FT_Error |
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ft_lzw_check_header( FT_Stream stream ) |
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{ |
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FT_Error error; |
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FT_Byte head[2]; |
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if ( FT_STREAM_SEEK( 0 ) || |
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FT_STREAM_READ( head, 2 ) ) |
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goto Exit; |
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/* head[0] && head[1] are the magic numbers */ |
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if ( head[0] != 0x1f || |
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head[1] != 0x9d ) |
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error = LZW_Err_Invalid_File_Format; |
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Exit: |
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return error; |
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} |
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static FT_Error |
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ft_lzw_file_init( FT_LZWFile zip, |
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FT_Stream stream, |
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FT_Stream source ) |
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{ |
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FT_LzwState lzw = &zip->lzw; |
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FT_Error error = LZW_Err_Ok; |
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zip->stream = stream; |
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zip->source = source; |
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zip->memory = stream->memory; |
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zip->limit = zip->buffer + FT_LZW_BUFFER_SIZE; |
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zip->cursor = zip->limit; |
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zip->pos = 0; |
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/* check and skip .Z header */ |
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{ |
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stream = source; |
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error = ft_lzw_check_header( source ); |
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if ( error ) |
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goto Exit; |
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} |
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/* initialize internal lzw variable */ |
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ft_lzwstate_init( lzw, source ); |
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Exit: |
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return error; |
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} |
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static void |
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ft_lzw_file_done( FT_LZWFile zip ) |
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{ |
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/* clear the rest */ |
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ft_lzwstate_done( &zip->lzw ); |
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zip->memory = NULL; |
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zip->source = NULL; |
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zip->stream = NULL; |
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} |
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static FT_Error |
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ft_lzw_file_reset( FT_LZWFile zip ) |
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{ |
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FT_Stream stream = zip->source; |
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FT_Error error; |
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if ( !FT_STREAM_SEEK( 0 ) ) |
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{ |
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ft_lzwstate_reset( &zip->lzw ); |
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zip->limit = zip->buffer + FT_LZW_BUFFER_SIZE; |
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zip->cursor = zip->limit; |
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zip->pos = 0; |
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} |
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return error; |
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} |
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static FT_Error |
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ft_lzw_file_fill_output( FT_LZWFile zip ) |
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{ |
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FT_LzwState lzw = &zip->lzw; |
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FT_ULong count; |
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FT_Error error = 0; |
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zip->cursor = zip->buffer; |
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count = ft_lzwstate_io( lzw, zip->buffer, FT_LZW_BUFFER_SIZE ); |
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zip->limit = zip->cursor + count; |
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if ( count == 0 ) |
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error = LZW_Err_Invalid_Stream_Operation; |
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return error; |
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} |
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/* fill output buffer; `count' must be <= FT_LZW_BUFFER_SIZE */ |
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static FT_Error |
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ft_lzw_file_skip_output( FT_LZWFile zip, |
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FT_ULong count ) |
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{ |
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FT_Error error = LZW_Err_Ok; |
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/* first, we skip what we can from the output buffer
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*/ |
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{ |
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FT_ULong delta = (FT_ULong)( zip->limit - zip->cursor ); |
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if ( delta >= count ) |
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delta = count; |
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zip->cursor += delta; |
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zip->pos += delta; |
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count -= delta; |
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} |
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/* next, we skip as many bytes remaining as possible
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*/ |
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while ( count > 0 ) |
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{ |
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FT_ULong delta = FT_LZW_BUFFER_SIZE; |
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FT_ULong numread; |
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if ( delta > count ) |
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delta = count; |
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numread = ft_lzwstate_io( &zip->lzw, NULL, delta ); |
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if ( numread < delta ) |
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{ |
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/* not enough bytes */ |
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error = LZW_Err_Invalid_Stream_Operation; |
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break; |
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} |
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zip->pos += delta; |
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count -= delta; |
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} |
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return error; |
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} |
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static FT_ULong |
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ft_lzw_file_io( FT_LZWFile zip, |
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FT_ULong pos, |
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FT_Byte* buffer, |
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FT_ULong count ) |
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{ |
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FT_ULong result = 0; |
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FT_Error error; |
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/* seeking backwards. */ |
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if ( pos < zip->pos ) |
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{ |
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/* if the new position is within the output buffer, simply
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* decrement pointers, otherwise, we'll reset the stream completely !! |
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*/ |
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if ( (zip->pos - pos) <= (FT_ULong)(zip->cursor - zip->buffer) ) |
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{ |
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zip->cursor -= (zip->pos - pos); |
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zip->pos = pos; |
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} |
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else |
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{ |
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error = ft_lzw_file_reset( zip ); |
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if ( error ) |
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goto Exit; |
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} |
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} |
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/* skip unwanted bytes */ |
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if ( pos > zip->pos ) |
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{ |
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error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) ); |
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if ( error ) |
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goto Exit; |
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} |
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if ( count == 0 ) |
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goto Exit; |
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/* now read the data */ |
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for (;;) |
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{ |
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FT_ULong delta; |
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delta = (FT_ULong)( zip->limit - zip->cursor ); |
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if ( delta >= count ) |
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delta = count; |
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FT_MEM_COPY( buffer + result, zip->cursor, delta ); |
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result += delta; |
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zip->cursor += delta; |
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zip->pos += delta; |
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count -= delta; |
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if ( count == 0 ) |
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break; |
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error = ft_lzw_file_fill_output( zip ); |
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if ( error ) |
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break; |
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} |
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Exit: |
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return result; |
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} |
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/***************************************************************************/ |
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/***************************************************************************/ |
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/***** *****/ |
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/***** L Z W E M B E D D I N G S T R E A M *****/ |
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/***** *****/ |
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/***************************************************************************/ |
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/***************************************************************************/ |
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static void |
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ft_lzw_stream_close( FT_Stream stream ) |
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{ |
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FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer; |
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FT_Memory memory = stream->memory; |
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if ( zip ) |
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{ |
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/* finalize lzw file descriptor */ |
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ft_lzw_file_done( zip ); |
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FT_FREE( zip ); |
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stream->descriptor.pointer = NULL; |
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} |
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} |
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static FT_ULong |
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ft_lzw_stream_io( FT_Stream stream, |
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FT_ULong pos, |
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FT_Byte* buffer, |
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FT_ULong count ) |
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{ |
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FT_LZWFile zip = (FT_LZWFile)stream->descriptor.pointer; |
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return ft_lzw_file_io( zip, pos, buffer, count ); |
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} |
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FT_EXPORT_DEF( FT_Error ) |
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FT_Stream_OpenLZW( FT_Stream stream, |
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FT_Stream source ) |
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{ |
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FT_Error error; |
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FT_Memory memory = source->memory; |
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FT_LZWFile zip; |
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/*
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* Check the header right now; this prevents allocation a huge |
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* LZWFile object (400 KByte of heap memory) if not necessary. |
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* |
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* Did I mention that you should never use .Z compressed font |
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* file? |
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*/ |
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error = ft_lzw_check_header( source ); |
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if ( error ) |
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goto Exit; |
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FT_ZERO( stream ); |
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stream->memory = memory; |
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if ( !FT_NEW( zip ) ) |
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{ |
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error = ft_lzw_file_init( zip, stream, source ); |
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if ( error ) |
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{ |
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FT_FREE( zip ); |
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goto Exit; |
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} |
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stream->descriptor.pointer = zip; |
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} |
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stream->size = 0x7FFFFFFFL; /* don't know the real size! */ |
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stream->pos = 0; |
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stream->base = 0; |
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stream->read = ft_lzw_stream_io; |
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stream->close = ft_lzw_stream_close; |
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Exit: |
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return error; |
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} |
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#include "ftzopen.c" |
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#else /* !FT_CONFIG_OPTION_USE_LZW */ |
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FT_EXPORT_DEF( FT_Error ) |
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FT_Stream_OpenLZW( FT_Stream stream, |
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FT_Stream source ) |
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{ |
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FT_UNUSED( stream ); |
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FT_UNUSED( source ); |
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return LZW_Err_Unimplemented_Feature; |
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} |
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#endif /* !FT_CONFIG_OPTION_USE_LZW */ |
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/* END */ |
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@ -0,0 +1,355 @@ |
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#include "ftzopen.h" |
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#include FT_INTERNAL_MEMORY_H |
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#include FT_INTERNAL_STREAM_H |
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#include FT_INTERNAL_DEBUG_H |
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/* refill input buffer, return 0 on success, or -1 if eof
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*/ |
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static int |
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ft_lzwstate_refill( FT_LzwState state ) |
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{ |
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int result = -1; |
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if ( !state->in_eof ) |
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{ |
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FT_ULong count = FT_Stream_TryRead( state->source, |
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state->in_buff, |
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sizeof( state->in_buff ) ); |
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state->in_cursor = state->in_buff; |
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state->in_limit = state->in_buff + count; |
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state->in_eof = FT_BOOL( count < sizeof( state->in_buff ) ); |
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if ( count > 0 ) |
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result = 0; |
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} |
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return result; |
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} |
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/* return new code of 'num_bits', or -1 if eof
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*/ |
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static FT_Int32 |
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ft_lzwstate_get_code( FT_LzwState state, |
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FT_UInt num_bits ) |
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{ |
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FT_Int32 result = -1; |
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FT_UInt32 pad = state->pad; |
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FT_UInt pad_bits = state->pad_bits; |
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while ( num_bits > pad_bits ) |
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{ |
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if ( state->in_cursor >= state->in_limit && |
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ft_lzwstate_refill( state ) < 0 ) |
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goto Exit; |
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pad |= (FT_UInt32)(*state->in_cursor++) << pad_bits; |
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pad_bits += 8; |
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} |
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result = (FT_Int32)( pad & LZW_MASK(num_bits) ); |
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state->pad_bits = pad_bits - num_bits; |
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state->pad = pad >> num_bits; |
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Exit: |
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return result; |
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} |
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/* grow the character stack
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*/ |
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static int |
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ft_lzwstate_stack_grow( FT_LzwState state ) |
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{ |
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if ( state->stack_top >= state->stack_size ) |
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{ |
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FT_Memory memory = state->memory; |
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FT_Error error; |
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FT_UInt old_size = state->stack_size; |
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FT_UInt new_size = old_size; |
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new_size = new_size + (new_size >> 1) + 4; |
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if ( state->stack == state->stack_0 ) |
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{ |
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state->stack = NULL; |
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old_size = 0; |
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} |
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if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) ) |
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return -1; |
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state->stack_size = new_size; |
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} |
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return 0; |
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} |
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/* grow the prefix/suffix arrays
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*/ |
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static int |
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ft_lzwstate_prefix_grow( FT_LzwState state ) |
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{ |
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FT_UInt old_size = state->prefix_size; |
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FT_UInt new_size = old_size; |
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FT_Memory memory = state->memory; |
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FT_Error error; |
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if ( new_size == 0 ) /* first allocation -> 9 bits */ |
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new_size = 512; |
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else |
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new_size += (new_size >> 2); /* don't grow too fast */ |
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/* note that the 'suffix' array is located in the same memory block
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* pointed to by 'prefix' |
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* |
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* I know that sizeof(FT_Byte) == 1 by definition, but it's clearer |
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* to write it literally |
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*/ |
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if ( FT_REALLOC( state->prefix, |
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old_size*(sizeof(FT_UShort)+sizeof(FT_Byte)), |
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new_size*(sizeof(FT_UShort)+sizeof(FT_Byte)) ) ) |
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return -1; |
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/* now adjust 'suffix' and move the data accordingly */ |
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state->suffix = (FT_Byte*)(state->prefix + new_size); |
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FT_MEM_MOVE( state->suffix, |
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state->prefix + old_size, |
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old_size * sizeof(FT_Byte) ); |
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state->prefix_size = new_size; |
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return 0; |
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} |
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_reset( FT_LzwState state ) |
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{ |
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state->in_cursor = state->in_buff; |
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state->in_limit = state->in_buff; |
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state->in_eof = 0; |
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state->pad_bits = 0; |
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state->pad = 0; |
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state->stack_top = 0; |
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state->num_bits = LZW_INIT_BITS; |
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state->phase = FT_LZW_PHASE_START; |
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} |
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_init( FT_LzwState state, |
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FT_Stream source ) |
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{ |
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FT_ZERO( state ); |
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state->source = source; |
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state->memory = source->memory; |
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state->prefix = NULL; |
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state->suffix = NULL; |
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state->prefix_size = 0; |
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state->stack = state->stack_0; |
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state->stack_size = sizeof(state->stack_0); |
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ft_lzwstate_reset( state ); |
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} |
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_done( FT_LzwState state ) |
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{ |
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FT_Memory memory = state->memory; |
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ft_lzwstate_reset( state ); |
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if ( state->stack != state->stack_0 ) |
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FT_FREE( state->stack ); |
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FT_FREE( state->prefix ); |
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state->suffix = NULL; |
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FT_ZERO( state ); |
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} |
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#define FTLZW_STACK_PUSH(c) \ |
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FT_BEGIN_STMNT \
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if ( state->stack_top >= state->stack_size && \
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ft_lzwstate_stack_grow( state ) < 0 ) \
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goto Eof; \
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\
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state->stack[ state->stack_top++ ] = (FT_Byte)(c); \
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FT_END_STMNT |
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FT_LOCAL_DEF( FT_ULong ) |
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ft_lzwstate_io( FT_LzwState state, |
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FT_Byte* buffer, |
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FT_ULong out_size ) |
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{ |
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FT_ULong result = 0; |
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|
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FT_UInt num_bits = state->num_bits; |
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FT_UInt free_ent = state->free_ent; |
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FT_UInt old_char = state->old_char; |
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FT_UInt old_code = state->old_code; |
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FT_UInt in_code = state->in_code; |
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|
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if ( out_size == 0 ) |
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goto Exit; |
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switch ( state->phase ) |
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{ |
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case FT_LZW_PHASE_START: |
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{ |
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FT_Byte max_bits; |
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FT_Int32 c; |
||||
|
||||
/* skip magic bytes, and read max_bits + block_flag */ |
||||
if ( FT_Stream_Seek( state->source, 2 ) != 0 || |
||||
FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 ) |
||||
goto Eof; |
||||
|
||||
state->max_bits = max_bits & LZW_BIT_MASK; |
||||
state->block_mode = max_bits & LZW_BLOCK_MASK; |
||||
state->max_free = (FT_UInt)((1UL << state->max_bits) - 256); |
||||
|
||||
if ( state->max_bits > LZW_MAX_BITS ) |
||||
goto Eof; |
||||
|
||||
num_bits = LZW_INIT_BITS; |
||||
free_ent = (state->block_mode ? LZW_FIRST : LZW_CLEAR) - 256; |
||||
in_code = 0; |
||||
|
||||
state->free_bits = num_bits < state->max_bits |
||||
? (FT_UInt)((1UL << num_bits) - 256) |
||||
: state->max_free+1; |
||||
|
||||
c = ft_lzwstate_get_code( state, num_bits ); |
||||
if ( c < 0 ) |
||||
goto Eof; |
||||
|
||||
old_code = old_char = (FT_UInt)c; |
||||
|
||||
if ( buffer ) |
||||
buffer[result] = (FT_Byte)old_char; |
||||
|
||||
if ( ++result >= out_size ) |
||||
goto Exit; |
||||
|
||||
state->phase = FT_LZW_PHASE_CODE; |
||||
} |
||||
/* fall-through */ |
||||
|
||||
case FT_LZW_PHASE_CODE: |
||||
{ |
||||
FT_Int32 c; |
||||
FT_UInt code; |
||||
|
||||
NextCode: |
||||
c = ft_lzwstate_get_code( state, num_bits ); |
||||
if ( c < 0 ) goto Eof; |
||||
|
||||
code = (FT_UInt)c; |
||||
|
||||
if ( code == LZW_CLEAR && state->block_mode ) |
||||
{ |
||||
free_ent = (LZW_FIRST-1)-256; /* why not LZW_FIRST-256 ? */ |
||||
num_bits = LZW_INIT_BITS; |
||||
|
||||
state->free_bits = num_bits < state->max_bits |
||||
? (FT_UInt)((1UL << num_bits) - 256) |
||||
: state->max_free+1; |
||||
|
||||
c = ft_lzwstate_get_code( state, num_bits ); |
||||
if ( c < 0 ) goto Eof; |
||||
|
||||
code = (FT_UInt)c; |
||||
} |
||||
|
||||
in_code = code; /* save code for later */ |
||||
|
||||
if ( code >= 256U ) |
||||
{ |
||||
/* special case for KwKwKwK */ |
||||
if ( code-256U >= free_ent ) |
||||
{ |
||||
FTLZW_STACK_PUSH( old_char ); |
||||
code = old_code; |
||||
} |
||||
|
||||
while ( code >= 256U ) |
||||
{ |
||||
FTLZW_STACK_PUSH( state->suffix[code-256] ); |
||||
code = state->prefix[code-256]; |
||||
} |
||||
} |
||||
|
||||
old_char = code; |
||||
FTLZW_STACK_PUSH(old_char); |
||||
|
||||
state->phase = FT_LZW_PHASE_STACK; |
||||
} |
||||
/* fall-through */ |
||||
|
||||
case FT_LZW_PHASE_STACK: |
||||
{ |
||||
while ( state->stack_top > 0 ) |
||||
{ |
||||
--state->stack_top; |
||||
|
||||
if ( buffer ) |
||||
buffer[result] = state->stack[state->stack_top]; |
||||
|
||||
if ( ++result == out_size ) |
||||
goto Exit; |
||||
} |
||||
|
||||
/* now create new entry */ |
||||
if ( free_ent < state->max_free ) |
||||
{ |
||||
if ( free_ent >= state->prefix_size && |
||||
ft_lzwstate_prefix_grow( state ) < 0 ) |
||||
goto Eof; |
||||
|
||||
FT_ASSERT( free_ent < state->prefix_size ); |
||||
|
||||
state->prefix[free_ent] = (FT_UShort) old_code; |
||||
state->suffix[free_ent] = (FT_Byte) old_char; |
||||
|
||||
if ( ++free_ent == state->free_bits ) |
||||
{ |
||||
num_bits++; |
||||
|
||||
state->free_bits = num_bits < state->max_bits |
||||
? (FT_UInt)((1UL << num_bits)-256) |
||||
: state->max_free+1; |
||||
} |
||||
} |
||||
|
||||
old_code = in_code; |
||||
|
||||
state->phase = FT_LZW_PHASE_CODE; |
||||
goto NextCode; |
||||
} |
||||
|
||||
default: /* state == EOF */ |
||||
; |
||||
} |
||||
Exit: |
||||
state->num_bits = num_bits; |
||||
state->free_ent = free_ent; |
||||
state->old_code = old_code; |
||||
state->old_char = old_char; |
||||
state->in_code = in_code; |
||||
|
||||
return result; |
||||
|
||||
Eof: |
||||
state->phase = FT_LZW_PHASE_EOF; |
||||
goto Exit; |
||||
} |
||||
@ -0,0 +1,142 @@ |
||||
#ifndef __FT_ZOPEN_H__ |
||||
#define __FT_ZOPEN_H__ |
||||
|
||||
#include <ft2build.h> |
||||
#include FT_FREETYPE_H |
||||
|
||||
/* this is a complete re-implementation of the LZW file reader,
|
||||
* since the old one was incredibly badly written, and used |
||||
* 400 Kb of heap memory before decompressing anything. |
||||
*/ |
||||
|
||||
#define FT_LZW_IN_BUFF_SIZE 64 |
||||
#define FT_LZW_DEFAULT_STACK_SIZE 64 |
||||
|
||||
#define LZW_INIT_BITS 9 |
||||
#define LZW_MAX_BITS 16 |
||||
|
||||
#define LZW_CLEAR 256 |
||||
#define LZW_FIRST 257 |
||||
|
||||
#define LZW_BIT_MASK 0x1f |
||||
#define LZW_BLOCK_MASK 0x80 |
||||
#define LZW_MASK(n) ((1U << (n)) - 1U) |
||||
|
||||
typedef enum |
||||
{ |
||||
FT_LZW_PHASE_START = 0, |
||||
FT_LZW_PHASE_CODE, |
||||
FT_LZW_PHASE_STACK, |
||||
FT_LZW_PHASE_EOF |
||||
|
||||
} FT_LzwPhase; |
||||
|
||||
|
||||
/* state of LZW decompressor
|
||||
* |
||||
* small technical note: |
||||
* |
||||
* we use a few tricks in this implementation that are explained here to |
||||
* ease debugging and maintenance. |
||||
* |
||||
* - first of all, the "prefix" and "suffix" arrays contain the |
||||
* suffix and prefix for codes over 256, this means that: |
||||
* |
||||
* prefix_of(code) == state->prefix[ code-256 ] |
||||
* suffix_of(code) == state->suffix[ code-256 ] |
||||
* |
||||
* each prefix is a 16-bit code, and each suffix an 8-bit byte |
||||
* |
||||
* both arrays are stored in a single memory block, pointed to by |
||||
* 'state->prefix', this means that the following equality is always |
||||
* true: |
||||
* |
||||
* state->suffix == (FT_Byte*)(state->prefix + state->prefix_size) |
||||
* |
||||
* of course, state->prefix_size is the number of prefix/suffix slots |
||||
* in the arrays, corresponding to codes 256..255+prefix_size |
||||
* |
||||
* - 'free_ent' is the index of the next free entry in the "prefix" |
||||
* and "suffix" arrays. This means that the corresponding "next free |
||||
* code" is really '256+free_ent' |
||||
* |
||||
* moreover, 'max_free' is the maximum value that 'free_ent' can reach. |
||||
* |
||||
* 'max_free' corresponds to "(1 << max_bits) - 256". Note that this value |
||||
* is always <= 0xFF00, which means that both 'free_ent' and 'max_free' can |
||||
* be stored in FT_UInt variable, even on 16-bit machines. |
||||
* |
||||
* if 'free_ent == max_free', you cannot add new codes to the prefix/suffix |
||||
* table. |
||||
* |
||||
* - 'num_bits' is the current number of code bits, starting at 9 and |
||||
* growing each time 'free_ent' reaches the value of 'free_bits'. the |
||||
* latter is computed as follows: |
||||
* |
||||
* if num_bits < max_bits: |
||||
* free_bits = (1 << num_bits)-256 |
||||
* else: |
||||
* free_bits = max_free + 1 |
||||
* |
||||
* since the value of 'max_free + 1' can never be reached by 'free_ent', |
||||
* 'num_bits' cannot grow larger than 'max_bits' |
||||
*/ |
||||
typedef struct |
||||
{ |
||||
FT_LzwPhase phase; |
||||
|
||||
FT_Int in_eof; |
||||
FT_Byte* in_cursor; /* current buffer pos */ |
||||
FT_Byte* in_limit; /* current buffer limit */ |
||||
|
||||
FT_UInt32 pad; /* a pad value where incoming bits were read */ |
||||
FT_Int pad_bits; /* number of meaningful bits in pad value */ |
||||
|
||||
FT_UInt max_bits; /* max code bits, from file header */ |
||||
FT_Int block_mode; /* block mode flag, from file header */ |
||||
FT_UInt max_free; /* (1 << max_bits) - 256 */ |
||||
|
||||
FT_UInt num_bits; /* current code bit number */ |
||||
FT_UInt free_ent; /* index of next free entry */ |
||||
FT_UInt free_bits; /* if free_ent reaches this, increment num_bits */ |
||||
FT_UInt old_code; |
||||
FT_UInt old_char; |
||||
FT_UInt in_code; |
||||
|
||||
FT_UShort* prefix; /* always dynamically allocated / reallocated */ |
||||
FT_Byte* suffix; /* suffix = (FT_Byte*)(prefix + prefix_size) */ |
||||
FT_UInt prefix_size; /* number of slots in 'prefix' or 'suffix' */ |
||||
|
||||
FT_Byte* stack; /* character stack */ |
||||
FT_UInt stack_top; |
||||
FT_UInt stack_size; |
||||
|
||||
FT_Byte in_buff[ FT_LZW_IN_BUFF_SIZE ]; /* small buffer to read data */ |
||||
FT_Byte stack_0[ FT_LZW_DEFAULT_STACK_SIZE ]; /* minimize heap alloc */ |
||||
|
||||
FT_Stream source; /* source stream */ |
||||
FT_Memory memory; |
||||
|
||||
} FT_LzwStateRec, *FT_LzwState; |
||||
|
||||
|
||||
FT_LOCAL( void ) |
||||
ft_lzwstate_init( FT_LzwState state, |
||||
FT_Stream source ); |
||||
|
||||
FT_LOCAL( void ) |
||||
ft_lzwstate_done( FT_LzwState state ); |
||||
|
||||
|
||||
FT_LOCAL( void ) |
||||
ft_lzwstate_reset( FT_LzwState state ); |
||||
|
||||
|
||||
FT_LOCAL( FT_ULong ) |
||||
ft_lzwstate_io( FT_LzwState state, |
||||
FT_Byte* buffer, |
||||
FT_ULong out_size ); |
||||
|
||||
/* */ |
||||
|
||||
#endif /* __FT_ZOPEN_H__ */ |
||||
Loading…
Reference in new issue