/* This file is part of libmspack.
  * (C) 2003-2004 Stuart Caie.
  *
  * The Quantum method was created by David Stafford, adapted by Microsoft
  * Corporation.
  *
  * libmspack is free software; you can redistribute it and/or modify it under
  * the terms of the GNU Lesser General Public License (LGPL) version 2.1
  *
  * For further details, see the file COPYING.LIB distributed with libmspack
  */
 
 #ifndef MSPACK_QTM_H
 #define MSPACK_QTM_H 1
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /* Quantum compression / decompression definitions */
 
 #define QTM_FRAME_SIZE (32768)
 
 struct qtmd_modelsym {
   unsigned short sym, cumfreq;
 };
 
 struct qtmd_model {
   int shiftsleft, entries;
   struct qtmd_modelsym *syms;
 };
 
 struct qtmd_stream {
   struct mspack_system *sys;      /* I/O routines                            */
   struct mspack_file   *input;    /* input file handle                       */
   struct mspack_file   *output;   /* output file handle                      */
 
   unsigned char *window;          /* decoding window                         */
   unsigned int window_size;       /* window size                             */
   unsigned int window_posn;       /* decompression offset within window      */
   unsigned int frame_todo;        /* bytes remaining for current frame       */
 
   unsigned short H, L, C;         /* high/low/current: arith coding state    */
   unsigned char header_read;      /* have we started decoding a new frame?   */
 
   int error;
 
   /* I/O buffers */
   unsigned char *inbuf, *i_ptr, *i_end, *o_ptr, *o_end;
   unsigned int  bit_buffer, inbuf_size;
   unsigned char bits_left, input_end;
 
   /* four literal models, each representing 64 symbols
    * model0 for literals from   0 to  63 (selector = 0)
    * model1 for literals from  64 to 127 (selector = 1)
    * model2 for literals from 128 to 191 (selector = 2)
    * model3 for literals from 129 to 255 (selector = 3) */
   struct qtmd_model model0, model1, model2, model3;
 
   /* three match models.
    * model4 for match with fixed length of 3 bytes
    * model5 for match with fixed length of 4 bytes
    * model6 for variable length match, encoded with model6len model */
   struct qtmd_model model4, model5, model6, model6len;
 
   /* selector model. 0-6 to say literal (0,1,2,3) or match (4,5,6) */
   struct qtmd_model model7;
 
   /* symbol arrays for all models */
   struct qtmd_modelsym m0sym[64 + 1];
   struct qtmd_modelsym m1sym[64 + 1];
   struct qtmd_modelsym m2sym[64 + 1];
   struct qtmd_modelsym m3sym[64 + 1];
   struct qtmd_modelsym m4sym[24 + 1];
   struct qtmd_modelsym m5sym[36 + 1];
   struct qtmd_modelsym m6sym[42 + 1], m6lsym[27 + 1];
   struct qtmd_modelsym m7sym[7 + 1];
 };
 
 /* allocates Quantum decompression state for decoding the given stream.
  *
  * - returns NULL if window_bits is outwith the range 10 to 21 (inclusive).
  *
  * - uses system->alloc() to allocate memory
  *
  * - returns NULL if not enough memory
  *
  * - window_bits is the size of the Quantum window, from 1Kb (10) to 2Mb (21).
  *
  * - input_buffer_size is the number of bytes to use to store bitstream data.
  */
 extern struct qtmd_stream *qtmd_init(struct mspack_system *system,

                                      struct mspack_file *input,
                                      struct mspack_file *output,
                                      int window_bits,
                                      int input_buffer_size);

 
 /* decompresses, or decompresses more of, a Quantum stream.
  *
  * - out_bytes of data will be decompressed and the function will return
  *   with an MSPACK_ERR_OK return code.
  *
  * - decompressing will stop as soon as out_bytes is reached. if the true
  *   amount of bytes decoded spills over that amount, they will be kept for
  *   a later invocation of qtmd_decompress().
  *
  * - the output bytes will be passed to the system->write() function given in
  *   qtmd_init(), using the output file handle given in qtmd_init(). More
  *   than one call may be made to system->write()
  *
  * - Quantum will read input bytes as necessary using the system->read()
  *   function given in qtmd_init(), using the input file handle given in
  *   qtmd_init(). This will continue until system->read() returns 0 bytes,
  *   or an error.
  */
 extern int qtmd_decompress(struct qtmd_stream *qtm, off_t out_bytes);
 
 /* frees all state associated with a Quantum data stream
  *
  * - calls system->free() using the system pointer given in qtmd_init()
  */
 void qtmd_free(struct qtmd_stream *qtm);
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif