path: root/contrib/libs/zlib/deflate.h

/* deflate.h -- internal compression state 
 * Copyright (C) 1995-2016 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. 
 */ 
 
/* @(#) $Id$ */ 
 
#ifndef DEFLATE_H
#define DEFLATE_H

#include "zutil.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 
 
/* =========================================================================== 
 * Internal compression state. 
 */ 
 
#define LENGTH_CODES 29 
/* number of length codes, not counting the special END_BLOCK code */ 
 
#define LITERALS  256 
/* number of literal bytes 0..255 */ 
 
#define L_CODES (LITERALS+1+LENGTH_CODES) 
/* number of Literal or Length codes, including the END_BLOCK code */ 
 
#define D_CODES   30 
/* number of distance codes */ 
 
#define BL_CODES  19 
/* number of codes used to transfer the bit lengths */ 
 
#define HEAP_SIZE (2*L_CODES+1) 
/* maximum heap size */ 
 
#define MAX_BITS 15 
/* All codes must not exceed MAX_BITS bits */ 
 
#define Buf_size 16 
/* size of bit buffer in bi_buf */ 
 
#define INIT_STATE    42    /* zlib header -> BUSY_STATE */
#ifdef GZIP
#  define GZIP_STATE  57    /* gzip header -> BUSY_STATE | EXTRA_STATE */
#endif
#define EXTRA_STATE   69    /* gzip extra block -> NAME_STATE */
#define NAME_STATE    73    /* gzip file name -> COMMENT_STATE */
#define COMMENT_STATE 91    /* gzip comment -> HCRC_STATE */
#define HCRC_STATE   103    /* gzip header CRC -> BUSY_STATE */
#define BUSY_STATE   113    /* deflate -> FINISH_STATE */
#define FINISH_STATE 666    /* stream complete */
/* Stream status */ 
 
 
/* Data structure describing a single value and its code string. */ 
typedef struct ct_data_s { 
    union { 
        ush  freq;       /* frequency count */ 
        ush  code;       /* bit string */ 
    } fc; 
    union { 
        ush  dad;        /* father node in Huffman tree */ 
        ush  len;        /* length of bit string */ 
    } dl; 
} FAR ct_data; 
 
#define Freq fc.freq 
#define Code fc.code 
#define Dad  dl.dad 
#define Len  dl.len 
 
typedef struct static_tree_desc_s  static_tree_desc; 
 
typedef struct tree_desc_s { 
    ct_data *dyn_tree;           /* the dynamic tree */ 
    int     max_code;            /* largest code with non zero frequency */ 
    const static_tree_desc *stat_desc;  /* the corresponding static tree */
} FAR tree_desc; 
 
typedef ush Pos; 
typedef Pos FAR Posf; 
typedef unsigned IPos; 
 
/* A Pos is an index in the character window. We use short instead of int to 
 * save space in the various tables. IPos is used only for parameter passing. 
 */ 
 
typedef struct internal_state { 
    z_streamp strm;      /* pointer back to this zlib stream */ 
    int   status;        /* as the name implies */ 
    Bytef *pending_buf;  /* output still pending */ 
    ulg   pending_buf_size; /* size of pending_buf */ 
    Bytef *pending_out;  /* next pending byte to output to the stream */ 
    ulg   pending;       /* nb of bytes in the pending buffer */
    int   wrap;          /* bit 0 true for zlib, bit 1 true for gzip */ 
    gz_headerp  gzhead;  /* gzip header information to write */ 
    ulg   gzindex;       /* where in extra, name, or comment */
    Byte  method;        /* can only be DEFLATED */ 
    int   last_flush;    /* value of flush param for previous deflate call */ 
 
                /* used by deflate.c: */ 
 
    uInt  w_size;        /* LZ77 window size (32K by default) */ 
    uInt  w_bits;        /* log2(w_size)  (8..16) */ 
    uInt  w_mask;        /* w_size - 1 */ 
 
    Bytef *window; 
    /* Sliding window. Input bytes are read into the second half of the window, 
     * and move to the first half later to keep a dictionary of at least wSize 
     * bytes. With this organization, matches are limited to a distance of 
     * wSize-MAX_MATCH bytes, but this ensures that IO is always 
     * performed with a length multiple of the block size. Also, it limits 
     * the window size to 64K, which is quite useful on MSDOS. 
     * To do: use the user input buffer as sliding window. 
     */ 
 
    ulg window_size; 
    /* Actual size of window: 2*wSize, except when the user input buffer 
     * is directly used as sliding window. 
     */ 
 
    Posf *prev; 
    /* Link to older string with same hash index. To limit the size of this 
     * array to 64K, this link is maintained only for the last 32K strings. 
     * An index in this array is thus a window index modulo 32K. 
     */ 
 
    Posf *head; /* Heads of the hash chains or NIL. */ 
 
    uInt  ins_h;          /* hash index of string to be inserted */ 
    uInt  hash_size;      /* number of elements in hash table */ 
    uInt  hash_bits;      /* log2(hash_size) */ 
    uInt  hash_mask;      /* hash_size-1 */ 
 
    uInt  hash_shift; 
    /* Number of bits by which ins_h must be shifted at each input 
     * step. It must be such that after MIN_MATCH steps, the oldest 
     * byte no longer takes part in the hash key, that is: 
     *   hash_shift * MIN_MATCH >= hash_bits 
     */ 
 
    long block_start; 
    /* Window position at the beginning of the current output block. Gets 
     * negative when the window is moved backwards. 
     */ 
 
    uInt match_length;           /* length of best match */ 
    IPos prev_match;             /* previous match */ 
    int match_available;         /* set if previous match exists */ 
    uInt strstart;               /* start of string to insert */ 
    uInt match_start;            /* start of matching string */ 
    uInt lookahead;              /* number of valid bytes ahead in window */ 
 
    uInt prev_length; 
    /* Length of the best match at previous step. Matches not greater than this 
     * are discarded. This is used in the lazy match evaluation. 
     */ 
 
    uInt max_chain_length; 
    /* To speed up deflation, hash chains are never searched beyond this 
     * length.  A higher limit improves compression ratio but degrades the 
     * speed. 
     */ 
 
    uInt max_lazy_match; 
    /* Attempt to find a better match only when the current match is strictly 
     * smaller than this value. This mechanism is used only for compression 
     * levels >= 4. 
     */ 
#   define max_insert_length  max_lazy_match 
    /* Insert new strings in the hash table only if the match length is not 
     * greater than this length. This saves time but degrades compression. 
     * max_insert_length is used only for compression levels <= 3. 
     */ 
 
    int level;    /* compression level (1..9) */ 
    int strategy; /* favor or force Huffman coding*/ 
 
    uInt good_match; 
    /* Use a faster search when the previous match is longer than this */ 
 
    int nice_match; /* Stop searching when current match exceeds this */ 
 
                /* used by trees.c: */ 
    /* Didn't use ct_data typedef below to suppress compiler warning */ 
    struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */ 
    struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ 
    struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */ 
 
    struct tree_desc_s l_desc;               /* desc. for literal tree */ 
    struct tree_desc_s d_desc;               /* desc. for distance tree */ 
    struct tree_desc_s bl_desc;              /* desc. for bit length tree */ 
 
    ush bl_count[MAX_BITS+1]; 
    /* number of codes at each bit length for an optimal tree */ 
 
    int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */ 
    int heap_len;               /* number of elements in the heap */ 
    int heap_max;               /* element of largest frequency */ 
    /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. 
     * 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 
     */ 
 
    uchf *l_buf;          /* buffer for literals or lengths */ 
 
    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 
     *     when input comes from standard input.  (This can also be done for 
     *     all blocks if lit_bufsize is not greater than 32K.) 
     *   - if compression is not successful for a file smaller than 64K, we can 
     *     even emit a stored file instead of a stored block (saving 5 bytes). 
     *     This is applicable only for zip (not gzip or zlib). 
     *   - creating new Huffman trees less frequently may not provide fast 
     *     adaptation to changes in the input data statistics. (Take for 
     *     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 last_lit;      /* running index in l_buf */ 
 
    ushf *d_buf; 
    /* Buffer for distances. To simplify the code, d_buf and l_buf have 
     * the same number of elements. To use different lengths, an extra flag 
     * array would be necessary. 
     */ 
 
    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 */ 
 
#ifdef ZLIB_DEBUG
    ulg compressed_len; /* total bit length of compressed file mod 2^32 */ 
    ulg bits_sent;      /* bit length of compressed data sent mod 2^32 */ 
#endif 
 
    ush bi_buf; 
    /* Output buffer. bits are inserted starting at the bottom (least 
     * significant bits). 
     */ 
    int bi_valid; 
    /* Number of valid bits in bi_buf.  All bits above the last valid bit 
     * are always zero. 
     */ 
 
    ulg high_water; 
    /* High water mark offset in window for initialized bytes -- bytes above 
     * this are set to zero in order to avoid memory check warnings when 
     * longest match routines access bytes past the input.  This is then 
     * updated to the new high water mark. 
     */ 
 
} FAR deflate_state; 
 
/* Output a byte on the stream. 
 * IN assertion: there is enough room in pending_buf. 
 */ 
#define put_byte(s, c) {s->pending_buf[s->pending++] = (Bytef)(c);}
 
 
#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) 
/* Minimum amount of lookahead, except at the end of the input file. 
 * See deflate.c for comments about the MIN_MATCH+1. 
 */ 
 
#define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD) 
/* In order to simplify the code, particularly on 16 bit machines, match 
 * distances are limited to MAX_DIST instead of WSIZE. 
 */ 
 
#define WIN_INIT MAX_MATCH 
/* Number of bytes after end of data in window to initialize in order to avoid 
   memory checker errors from longest match routines */ 
 
        /* in trees.c */ 
void ZLIB_INTERNAL _tr_init OF((deflate_state *s)); 
int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); 
void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf, 
                        ulg stored_len, int last)); 
void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s)); 
void ZLIB_INTERNAL _tr_align OF((deflate_state *s)); 
void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf, 
                        ulg stored_len, int last)); 
 
#define d_code(dist) \ 
   ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)]) 
/* Mapping from a distance to a distance code. dist is the distance - 1 and 
 * must not have side effects. _dist_code[256] and _dist_code[257] are never 
 * used. 
 */ 
 
#ifndef ZLIB_DEBUG
/* Inline versions of _tr_tally for speed: */ 
 
#if defined(GEN_TREES_H) || !defined(STDC) 
  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 
 
# define _tr_tally_lit(s, c, flush) \ 
  { uch cc = (c); \ 
    s->d_buf[s->last_lit] = 0; \ 
    s->l_buf[s->last_lit++] = cc; \ 
    s->dyn_ltree[cc].Freq++; \ 
    flush = (s->last_lit == s->lit_bufsize-1); \ 
   } 
# define _tr_tally_dist(s, distance, length, flush) \ 
  { uch len = (uch)(length); \
    ush dist = (ush)(distance); \
    s->d_buf[s->last_lit] = dist; \ 
    s->l_buf[s->last_lit++] = len; \ 
    dist--; \ 
    s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ 
    s->dyn_dtree[d_code(dist)].Freq++; \ 
    flush = (s->last_lit == s->lit_bufsize-1); \ 
  } 
#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 */