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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /modules/freetype2/src/lzw/ftzopen.h | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'modules/freetype2/src/lzw/ftzopen.h')
-rw-r--r-- | modules/freetype2/src/lzw/ftzopen.h | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/modules/freetype2/src/lzw/ftzopen.h b/modules/freetype2/src/lzw/ftzopen.h new file mode 100644 index 0000000000..6c7563643f --- /dev/null +++ b/modules/freetype2/src/lzw/ftzopen.h @@ -0,0 +1,174 @@ +/**************************************************************************** + * + * 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 (C) 2005-2023 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 FTZOPEN_H_ +#define FTZOPEN_H_ + +#include <freetype/freetype.h> + +FT_BEGIN_HEADER + + /* + * 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_UInt buf_offset; + FT_UInt 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 ); + +/* */ + +FT_END_HEADER + +#endif /* FTZOPEN_H_ */ + + +/* END */ |