text: /***************************************************************************/
  /*                                                                         */
  /*  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 */
  