Fossil

/* deflate.h -- internal compression state
 * Copyright (C) 1995-2018 Jean-loup Gailly
 * Copyright (C) 1995-2024 Jean-loup Gailly
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the compression library and is
   subject to change. Applications should only use zlib.h.
 */

/* define NO_GZIP when compiling if you want to disable gzip header and
   trailer creation by deflate().  NO_GZIP would be used to avoid linking in
   the crc code when it is not needed.  For shared libraries, gzip encoding
   should be left enabled. */
#ifndef NO_GZIP
#  define GZIP
#endif

/* define LIT_MEM to slightly increase the speed of deflate (order 1% to 2%) at
   the cost of a larger memory footprint */
/* #define LIT_MEM */

/* ===========================================================================
 * Internal compression state.
 */

#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

     * The same heap array is used to build all trees.
     */

    uch depth[2*L_CODES+1];
    /* Depth of each subtree used as tie breaker for trees of equal frequency
     */

#ifdef LIT_MEM
#   define LIT_BUFS 5
    ushf *d_buf;          /* buffer for distances */
    uchf *l_buf;          /* buffer for literals/lengths */
#else
#   define LIT_BUFS 4
    uchf *sym_buf;        /* buffer for distances and literals/lengths */
#endif

    uInt  lit_bufsize;
    /* Size of match buffer for literals/lengths.  There are 4 reasons for
     * limiting lit_bufsize to 64K:
     *   - frequencies can be kept in 16 bit counters
     *   - if compression is not successful for the first block, all input
     *     data is still in the window so we can still emit a stored block even

     *     example a binary file with poorly compressible code followed by
     *     a highly compressible string table.) Smaller buffer sizes give
     *     fast adaptation but have of course the overhead of transmitting
     *     trees more frequently.
     *   - I can't count above 4
     */

    uInt sym_next;      /* running index in sym_buf */
    uInt sym_next;      /* running index in symbol buffer */
    uInt sym_end;       /* symbol table full when sym_next reaches this */

    ulg opt_len;        /* bit length of current block with optimal trees */
    ulg static_len;     /* bit length of current block with static trees */
    uInt matches;       /* number of string matches in current block */
    uInt insert;        /* bytes at end of window left to insert */

  extern uch ZLIB_INTERNAL _length_code[];
  extern uch ZLIB_INTERNAL _dist_code[];
#else
  extern const uch ZLIB_INTERNAL _length_code[];
  extern const uch ZLIB_INTERNAL _dist_code[];
#endif

#ifdef LIT_MEM
# define _tr_tally_lit(s, c, flush) \
  { uch cc = (c); \
    s->d_buf[s->sym_next] = 0; \
    s->l_buf[s->sym_next++] = cc; \
    s->dyn_ltree[cc].Freq++; \
    flush = (s->sym_next == s->sym_end); \
   }
# define _tr_tally_dist(s, distance, length, flush) \
  { uch len = (uch)(length); \
    ush dist = (ush)(distance); \
    s->d_buf[s->sym_next] = dist; \
    s->l_buf[s->sym_next++] = len; \
    dist--; \
    s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
    s->dyn_dtree[d_code(dist)].Freq++; \
    flush = (s->sym_next == s->sym_end); \
  }
#else
# define _tr_tally_lit(s, c, flush) \
  { uch cc = (c); \
    s->sym_buf[s->sym_next++] = 0; \
    s->sym_buf[s->sym_next++] = 0; \
    s->sym_buf[s->sym_next++] = cc; \
    s->dyn_ltree[cc].Freq++; \
    flush = (s->sym_next == s->sym_end); \
   }
# define _tr_tally_dist(s, distance, length, flush) \
  { uch len = (uch)(length); \
    ush dist = (ush)(distance); \
    s->sym_buf[s->sym_next++] = (uch)dist; \
    s->sym_buf[s->sym_next++] = (uch)(dist >> 8); \
    s->sym_buf[s->sym_next++] = len; \
    dist--; \
    s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
    s->dyn_dtree[d_code(dist)].Freq++; \
    flush = (s->sym_next == s->sym_end); \
  }
#endif
#else
# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
# define _tr_tally_dist(s, distance, length, flush) \
              flush = _tr_tally(s, distance, length)
#endif

#endif /* DEFLATE_H */