Edit
kc3-lang/freetype/src/lzw/ftzopen.h
suzuki toshiya
- src/lzw/ftzopen.h
-
/***************************************************************************/ /* */ /* ftzopen.h */ /* */ /* FreeType support for .Z compressed files. */ /* */ /* This optional component relies on NetBSD's zopen(). It should mainly */ /* be used to parse compressed PCF fonts, as found with many X11 server */ /* distributions. */ /* */ /* Copyright 2005, 2006, 2007, 2008 by David Turner. */ /* */ /* This file is part of the FreeType project, and may only be used, */ /* modified, and distributed under the terms of the FreeType project */ /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ /* this file you indicate that you have read the license and */ /* understand and accept it fully. */ /* */ /***************************************************************************/ #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, using * 400 KByte 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_LzwPhase_ { 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 an 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_LzwStateRec_ { FT_LzwPhase phase; FT_Int in_eof; FT_Byte buf_tab[16]; FT_Int buf_offset; FT_Int buf_size; FT_Bool buf_clear; FT_Offset buf_total; 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 reached by free_ent, 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_Offset stack_size; 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__ */ /* END */