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/***************************************************************************/
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/* FreeType support for .Z compressed files. */
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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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/* Copyright 2005, 2006, 2007, 2008 by David Turner. */
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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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#ifndef __FT_ZOPEN_H__
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#define __FT_ZOPEN_H__
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#include FT_FREETYPE_H
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* This is a complete re-implementation of the LZW file reader,
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* since the old one was incredibly badly written, using
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* 400 KByte of heap memory before decompressing anything.
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#define FT_LZW_IN_BUFF_SIZE 64
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#define FT_LZW_DEFAULT_STACK_SIZE 64
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#define LZW_INIT_BITS 9
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#define LZW_MAX_BITS 16
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#define LZW_BIT_MASK 0x1f
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#define LZW_BLOCK_MASK 0x80
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#define LZW_MASK( n ) ( ( 1U << (n) ) - 1U )
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typedef enum FT_LzwPhase_
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FT_LZW_PHASE_START = 0,
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* state of LZW decompressor
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* small technical note
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* --------------------
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* We use a few tricks in this implementation that are explained here to
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* ease debugging and maintenance.
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* - First of all, the `prefix' and `suffix' arrays contain the suffix
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* and prefix for codes over 256; this means that
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* prefix_of(code) == state->prefix[code-256]
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* suffix_of(code) == state->suffix[code-256]
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* Each prefix is a 16-bit code, and each suffix an 8-bit byte.
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* Both arrays are stored in a single memory block, pointed to by
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* `state->prefix'. This means that the following equality is always
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* state->suffix == (FT_Byte*)(state->prefix + state->prefix_size)
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* Of course, state->prefix_size is the number of prefix/suffix slots
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* in the arrays, corresponding to codes 256..255+prefix_size.
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* - `free_ent' is the index of the next free entry in the `prefix'
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* and `suffix' arrays. This means that the corresponding `next free
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* code' is really `256+free_ent'.
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* Moreover, `max_free' is the maximum value that `free_ent' can reach.
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* `max_free' corresponds to `(1 << max_bits) - 256'. Note that this
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* value is always <= 0xFF00, which means that both `free_ent' and
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* `max_free' can be stored in an FT_UInt variable, even on 16-bit
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* If `free_ent == max_free', you cannot add new codes to the
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* prefix/suffix table.
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* - `num_bits' is the current number of code bits, starting at 9 and
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* growing each time `free_ent' reaches the value of `free_bits'. The
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* latter is computed as follows
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* if num_bits < max_bits:
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* free_bits = (1 << num_bits)-256
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* free_bits = max_free + 1
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* Since the value of `max_free + 1' can never be reached by
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* `free_ent', `num_bits' cannot grow larger than `max_bits'.
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typedef struct FT_LzwStateRec_
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FT_UInt max_bits; /* max code bits, from file header */
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FT_Int block_mode; /* block mode flag, from file header */
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FT_UInt max_free; /* (1 << max_bits) - 256 */
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FT_UInt num_bits; /* current code bit number */
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FT_UInt free_ent; /* index of next free entry */
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FT_UInt free_bits; /* if reached by free_ent, increment num_bits */
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FT_UShort* prefix; /* always dynamically allocated / reallocated */
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FT_Byte* suffix; /* suffix = (FT_Byte*)(prefix + prefix_size) */
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FT_UInt prefix_size; /* number of slots in `prefix' or `suffix' */
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FT_Byte* stack; /* character stack */
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FT_Offset stack_size;
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FT_Byte stack_0[FT_LZW_DEFAULT_STACK_SIZE]; /* minimize heap alloc */
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FT_Stream source; /* source stream */
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} FT_LzwStateRec, *FT_LzwState;
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ft_lzwstate_init( FT_LzwState state,
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ft_lzwstate_done( FT_LzwState state );
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ft_lzwstate_reset( FT_LzwState state );
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ft_lzwstate_io( FT_LzwState state,
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#endif /* __FT_ZOPEN_H__ */