deflate.h

/*
 * Copyright (c) 2021 Micha Mettke
 * https://github.com/vurtun/lib
 *
 * I have reformatted the code according to my coding style
 *
 * Copyright (C) 2021  Edward LEI <edward_lei72@hotmail.com>
 *
 * license: MIT license
 */

#ifndef _DEFLATE_H_
#define _DEFLATE_H_


#define SDEFL_MAX_OFF   (1 << 15)
#define SDEFL_WIN_SIZ   SDEFL_MAX_OFF
#define SDEFL_WIN_MSK   (SDEFL_WIN_SIZ-1)

#define SDEFL_HASH_BITS 15
#define SDEFL_HASH_SIZ  (1 << SDEFL_HASH_BITS)
#define SDEFL_HASH_MSK  (SDEFL_HASH_SIZ-1)

#define SDEFL_MIN_MATCH 4
#define SDEFL_BLK_MAX   (256*1024)
#define SDEFL_SEQ_SIZ   ((SDEFL_BLK_MAX + SDEFL_MIN_MATCH)/SDEFL_MIN_MATCH)

#define SDEFL_SYM_MAX   (288)
#define SDEFL_OFF_MAX   (32)
#define SDEFL_PRE_MAX   (19)

#define SDEFL_LVL_MIN   0
#define SDEFL_LVL_DEF   5
#define SDEFL_LVL_MAX   8

struct sdefl_freq {
  unsigned lit[SDEFL_SYM_MAX];
  unsigned off[SDEFL_OFF_MAX];
};

struct sdefl_code_words {
  unsigned lit[SDEFL_SYM_MAX];
  unsigned off[SDEFL_OFF_MAX];
};

struct sdefl_lens {
  unsigned char lit[SDEFL_SYM_MAX];
  unsigned char off[SDEFL_OFF_MAX];
};

struct sdefl_codes {
  struct sdefl_code_words word;
  struct sdefl_lens len;
};
struct sdefl_seqt {
  int off, len;
};

struct sdefl {
  int bits, bitcnt;
  int tbl[SDEFL_HASH_SIZ];
  int prv[SDEFL_WIN_SIZ];

  int seq_cnt;
  struct sdefl_seqt seq[SDEFL_SEQ_SIZ];
  struct sdefl_freq freq;
  struct sdefl_codes cod;
};


int deflate(struct sdefl *s,
            void *out,
            const void *in,
            int n,
            const int lvl);

int zdeflate(struct sdefl *s,
             void *out,
             const void *in,
             int n,
             const int lvl);

int deflate_bound(const int in_len);


#endif