lzx.h

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/* This file is part of libmspack.
 * (C) 2003-2013 Stuart Caie.
 *
 * The LZX method was created by Jonathan Forbes and Tomi Poutanen, 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_LZX_H
#define MSPACK_LZX_H 1
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* LZX compression / decompression definitions */
 
/* some constants defined by the LZX specification */
#define LZX_MIN_MATCH                (2)
#define LZX_MAX_MATCH                (257)
#define LZX_NUM_CHARS                (256)
#define LZX_BLOCKTYPE_INVALID        (0)   /* also blocktypes 4-7 invalid */
#define LZX_BLOCKTYPE_VERBATIM       (1)
#define LZX_BLOCKTYPE_ALIGNED        (2)
#define LZX_BLOCKTYPE_UNCOMPRESSED   (3)
#define LZX_PRETREE_NUM_ELEMENTS     (20)
#define LZX_ALIGNED_NUM_ELEMENTS     (8)   /* aligned offset tree #elements */
#define LZX_NUM_PRIMARY_LENGTHS      (7)   /* this one missing from spec! */
#define LZX_NUM_SECONDARY_LENGTHS    (249) /* length tree #elements */
 
/* LZX huffman defines: tweak tablebits as desired */
#define LZX_PRETREE_MAXSYMBOLS  (LZX_PRETREE_NUM_ELEMENTS)
#define LZX_PRETREE_TABLEBITS   (6)
#define LZX_MAINTREE_MAXSYMBOLS (LZX_NUM_CHARS + 290*8)
#define LZX_MAINTREE_TABLEBITS  (12)
#define LZX_LENGTH_MAXSYMBOLS   (LZX_NUM_SECONDARY_LENGTHS+1)
#define LZX_LENGTH_TABLEBITS    (12)
#define LZX_ALIGNED_MAXSYMBOLS  (LZX_ALIGNED_NUM_ELEMENTS)
#define LZX_ALIGNED_TABLEBITS   (7)
#define LZX_LENTABLE_SAFETY (64)  /* table decoding overruns are allowed */
 
#define LZX_FRAME_SIZE (32768) /* the size of a frame in LZX */
 
struct lzxd_stream {
  struct mspack_system *sys;      /* I/O routines                            */
  struct mspack_file   *input;    /* input file handle                       */
  struct mspack_file   *output;   /* output file handle                      */
 
  off_t   offset;                 /* number of bytes actually output         */
  off_t   length;                 /* overall decompressed length of stream   */
 
  unsigned char *window;          /* decoding window                         */
  unsigned int   window_size;     /* window size                             */
  unsigned int   ref_data_size;   /* LZX DELTA reference data size           */
  unsigned int   num_offsets;     /* number of match_offset entries in table */
  unsigned int   window_posn;     /* decompression offset within window      */
  unsigned int   frame_posn;      /* current frame offset within in window   */
  unsigned int   frame;           /* the number of 32kb frames processed     */
  unsigned int   reset_interval;  /* which frame do we reset the compressor? */
 
  unsigned int   R0, R1, R2;      /* for the LRU offset system               */
  unsigned int   block_length;    /* uncompressed length of this LZX block   */
  unsigned int   block_remaining; /* uncompressed bytes still left to decode */
 
  signed int     intel_filesize;  /* magic header value used for transform   */
 
  unsigned char  intel_started;   /* has intel E8 decoding started?          */
  unsigned char  block_type;      /* type of the current block               */
  unsigned char  header_read;     /* have we started decoding at all yet?    */
  unsigned char  input_end;       /* have we reached the end of input?       */
  unsigned char  is_delta;        /* does stream follow LZX DELTA spec?      */
 
  int error;
 
  /* I/O buffering */
  unsigned char *inbuf, *i_ptr, *i_end, *o_ptr, *o_end;
  unsigned int  bit_buffer, bits_left, inbuf_size;
 
  /* huffman code lengths */
  unsigned char PRETREE_len  [LZX_PRETREE_MAXSYMBOLS  + LZX_LENTABLE_SAFETY];
  unsigned char MAINTREE_len [LZX_MAINTREE_MAXSYMBOLS + LZX_LENTABLE_SAFETY];
  unsigned char LENGTH_len   [LZX_LENGTH_MAXSYMBOLS   + LZX_LENTABLE_SAFETY];
  unsigned char ALIGNED_len  [LZX_ALIGNED_MAXSYMBOLS  + LZX_LENTABLE_SAFETY];
 
  /* huffman decoding tables */
  unsigned short PRETREE_table [(1 << LZX_PRETREE_TABLEBITS) +
                                (LZX_PRETREE_MAXSYMBOLS * 2)];
  unsigned short MAINTREE_table[(1 << LZX_MAINTREE_TABLEBITS) +
                                (LZX_MAINTREE_MAXSYMBOLS * 2)];
  unsigned short LENGTH_table  [(1 << LZX_LENGTH_TABLEBITS) +
                                (LZX_LENGTH_MAXSYMBOLS * 2)];
  unsigned short ALIGNED_table [(1 << LZX_ALIGNED_TABLEBITS) +
                                (LZX_ALIGNED_MAXSYMBOLS * 2)];
  unsigned char LENGTH_empty;
 
  /* this is used purely for doing the intel E8 transform */
  unsigned char  e8_buf[LZX_FRAME_SIZE];
};
 
extern struct lzxd_stream *lzxd_init(struct mspack_system *system,
                                     struct mspack_file *input,
                                     struct mspack_file *output,
                                     int window_bits,
                                     int reset_interval,
                                     int input_buffer_size,
                                     off_t output_length,
                                     char is_delta);
 
/* see description of output_length in lzxd_init() */
extern void lzxd_set_output_length(struct lzxd_stream *lzx,
                                   off_t output_length);
 
extern int lzxd_set_reference_data(struct lzxd_stream *lzx,
                                   struct mspack_system *system,
                                   struct mspack_file *input,
                                   unsigned int length);
 
extern int lzxd_decompress(struct lzxd_stream *lzx, off_t out_bytes);
 
void lzxd_free(struct lzxd_stream *lzx);
 
#ifdef __cplusplus
}
#endif
 
#endif