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Member "zsync-0.6.2/zlib/deflate.h" (16 Sep 2010, 11942 Bytes) of package /linux/privat/old/zsync-0.6.2.tar.gz:


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    1 /* deflate.h -- internal compression state
    2  * Copyright (C) 1995-2002 Jean-loup Gailly
    3  * For conditions of distribution and use, see copyright notice in zlib.h
    4  */
    5 
    6 /* WARNING: this file should *not* be used by applications. It is
    7    part of the implementation of the compression library and is
    8    subject to change. Applications should only use zlib.h.
    9  */
   10 
   11 /* @(#) $Id$ */
   12 
   13 #ifndef DEFLATE_H
   14 #define DEFLATE_H
   15 
   16 #include "zutil.h"
   17 
   18 /* define NO_GZIP when compiling if you want to disable gzip header and
   19    trailer creation by deflate().  NO_GZIP would be used to avoid linking in
   20    the crc code when it is not needed.  For shared libraries, gzip encoding
   21    should be left enabled. */
   22 #ifndef NO_GZIP
   23 #  define GZIP
   24 #endif
   25 
   26 /* ===========================================================================
   27  * Internal compression state.
   28  */
   29 
   30 #define LENGTH_CODES 29
   31 /* number of length codes, not counting the special END_BLOCK code */
   32 
   33 #define LITERALS  256
   34 /* number of literal bytes 0..255 */
   35 
   36 #define L_CODES (LITERALS+1+LENGTH_CODES)
   37 /* number of Literal or Length codes, including the END_BLOCK code */
   38 
   39 #define D_CODES   30
   40 /* number of distance codes */
   41 
   42 #define BL_CODES  19
   43 /* number of codes used to transfer the bit lengths */
   44 
   45 #define HEAP_SIZE (2*L_CODES+1)
   46 /* maximum heap size */
   47 
   48 #define MAX_BITS 15
   49 /* All codes must not exceed MAX_BITS bits */
   50 
   51 #define INIT_STATE    42
   52 #define BUSY_STATE   113
   53 #define FINISH_STATE 666
   54 /* Stream status */
   55 
   56 
   57 /* Data structure describing a single value and its code string. */
   58 typedef struct ct_data_s {
   59     union {
   60         ush  freq;       /* frequency count */
   61         ush  code;       /* bit string */
   62     } fc;
   63     union {
   64         ush  dad;        /* father node in Huffman tree */
   65         ush  len;        /* length of bit string */
   66     } dl;
   67 } FAR ct_data;
   68 
   69 #define Freq fc.freq
   70 #define Code fc.code
   71 #define Dad  dl.dad
   72 #define Len  dl.len
   73 
   74 typedef struct static_tree_desc_s  static_tree_desc;
   75 
   76 typedef struct tree_desc_s {
   77     ct_data *dyn_tree;           /* the dynamic tree */
   78     int     max_code;            /* largest code with non zero frequency */
   79     static_tree_desc *stat_desc; /* the corresponding static tree */
   80 } FAR tree_desc;
   81 
   82 typedef ush Pos;
   83 typedef Pos FAR Posf;
   84 typedef unsigned IPos;
   85 
   86 /* A Pos is an index in the character window. We use short instead of int to
   87  * save space in the various tables. IPos is used only for parameter passing.
   88  */
   89 
   90 typedef struct internal_state {
   91     z_streamp strm;      /* pointer back to this zlib stream */
   92     int   status;        /* as the name implies */
   93     Bytef *pending_buf;  /* output still pending */
   94     ulg   pending_buf_size; /* size of pending_buf */
   95     Bytef *pending_out;  /* next pending byte to output to the stream */
   96     int   pending;       /* nb of bytes in the pending buffer */
   97     int   wrap;          /* bit 0 true for zlib, bit 1 true for gzip */
   98     Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
   99     Byte  method;        /* STORED (for zip only) or DEFLATED */
  100     int   last_flush;    /* value of flush param for previous deflate call */
  101 
  102                 /* used by deflate.c: */
  103 
  104     uInt  w_size;        /* LZ77 window size (32K by default) */
  105     uInt  w_bits;        /* log2(w_size)  (8..16) */
  106     uInt  w_mask;        /* w_size - 1 */
  107 
  108     Bytef *window;
  109     /* Sliding window. Input bytes are read into the second half of the window,
  110      * and move to the first half later to keep a dictionary of at least wSize
  111      * bytes. With this organization, matches are limited to a distance of
  112      * wSize-MAX_MATCH bytes, but this ensures that IO is always
  113      * performed with a length multiple of the block size. Also, it limits
  114      * the window size to 64K, which is quite useful on MSDOS.
  115      * To do: use the user input buffer as sliding window.
  116      */
  117 
  118     ulg window_size;
  119     /* Actual size of window: 2*wSize, except when the user input buffer
  120      * is directly used as sliding window.
  121      */
  122 
  123     Posf *prev;
  124     /* Link to older string with same hash index. To limit the size of this
  125      * array to 64K, this link is maintained only for the last 32K strings.
  126      * An index in this array is thus a window index modulo 32K.
  127      */
  128 
  129     Posf *head; /* Heads of the hash chains or NIL. */
  130 
  131     uInt  ins_h;          /* hash index of string to be inserted */
  132     uInt  hash_size;      /* number of elements in hash table */
  133     uInt  hash_bits;      /* log2(hash_size) */
  134     uInt  hash_mask;      /* hash_size-1 */
  135 
  136     uInt  hash_shift;
  137     /* Number of bits by which ins_h must be shifted at each input
  138      * step. It must be such that after MIN_MATCH steps, the oldest
  139      * byte no longer takes part in the hash key, that is:
  140      *   hash_shift * MIN_MATCH >= hash_bits
  141      */
  142 
  143     long block_start;
  144     /* Window position at the beginning of the current output block. Gets
  145      * negative when the window is moved backwards.
  146      */
  147 
  148     uInt match_length;           /* length of best match */
  149     IPos prev_match;             /* previous match */
  150     int match_available;         /* set if previous match exists */
  151     uInt strstart;               /* start of string to insert */
  152     uInt match_start;            /* start of matching string */
  153     uInt lookahead;              /* number of valid bytes ahead in window */
  154 
  155     uInt prev_length;
  156     /* Length of the best match at previous step. Matches not greater than this
  157      * are discarded. This is used in the lazy match evaluation.
  158      */
  159 
  160     uInt max_chain_length;
  161     /* To speed up deflation, hash chains are never searched beyond this
  162      * length.  A higher limit improves compression ratio but degrades the
  163      * speed.
  164      */
  165 
  166     uInt max_lazy_match;
  167     /* Attempt to find a better match only when the current match is strictly
  168      * smaller than this value. This mechanism is used only for compression
  169      * levels >= 4.
  170      */
  171 #   define max_insert_length  max_lazy_match
  172     /* Insert new strings in the hash table only if the match length is not
  173      * greater than this length. This saves time but degrades compression.
  174      * max_insert_length is used only for compression levels <= 3.
  175      */
  176 
  177     int level;    /* compression level (1..9) */
  178     int strategy; /* favor or force Huffman coding*/
  179 
  180     uInt good_match;
  181     /* Use a faster search when the previous match is longer than this */
  182 
  183     int nice_match; /* Stop searching when current match exceeds this */
  184 
  185                 /* used by trees.c: */
  186     /* Didn't use ct_data typedef below to supress compiler warning */
  187     struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
  188     struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
  189     struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */
  190 
  191     struct tree_desc_s l_desc;               /* desc. for literal tree */
  192     struct tree_desc_s d_desc;               /* desc. for distance tree */
  193     struct tree_desc_s bl_desc;              /* desc. for bit length tree */
  194 
  195     ush bl_count[MAX_BITS+1];
  196     /* number of codes at each bit length for an optimal tree */
  197 
  198     int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
  199     int heap_len;               /* number of elements in the heap */
  200     int heap_max;               /* element of largest frequency */
  201     /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
  202      * The same heap array is used to build all trees.
  203      */
  204 
  205     uch depth[2*L_CODES+1];
  206     /* Depth of each subtree used as tie breaker for trees of equal frequency
  207      */
  208 
  209     uchf *l_buf;          /* buffer for literals or lengths */
  210 
  211     uInt  lit_bufsize;
  212     /* Size of match buffer for literals/lengths.  There are 4 reasons for
  213      * limiting lit_bufsize to 64K:
  214      *   - frequencies can be kept in 16 bit counters
  215      *   - if compression is not successful for the first block, all input
  216      *     data is still in the window so we can still emit a stored block even
  217      *     when input comes from standard input.  (This can also be done for
  218      *     all blocks if lit_bufsize is not greater than 32K.)
  219      *   - if compression is not successful for a file smaller than 64K, we can
  220      *     even emit a stored file instead of a stored block (saving 5 bytes).
  221      *     This is applicable only for zip (not gzip or zlib).
  222      *   - creating new Huffman trees less frequently may not provide fast
  223      *     adaptation to changes in the input data statistics. (Take for
  224      *     example a binary file with poorly compressible code followed by
  225      *     a highly compressible string table.) Smaller buffer sizes give
  226      *     fast adaptation but have of course the overhead of transmitting
  227      *     trees more frequently.
  228      *   - I can't count above 4
  229      */
  230 
  231     uInt last_lit;      /* running index in l_buf */
  232 
  233     ushf *d_buf;
  234     /* Buffer for distances. To simplify the code, d_buf and l_buf have
  235      * the same number of elements. To use different lengths, an extra flag
  236      * array would be necessary.
  237      */
  238 
  239     ulg opt_len;        /* bit length of current block with optimal trees */
  240     ulg static_len;     /* bit length of current block with static trees */
  241     uInt matches;       /* number of string matches in current block */
  242     int last_eob_len;   /* bit length of EOB code for last block */
  243 
  244 #ifdef DEBUG
  245     ulg compressed_len; /* total bit length of compressed file mod 2^32 */
  246     ulg bits_sent;      /* bit length of compressed data sent mod 2^32 */
  247 #endif
  248 
  249     ush bi_buf;
  250     /* Output buffer. bits are inserted starting at the bottom (least
  251      * significant bits).
  252      */
  253     int bi_valid;
  254     /* Number of valid bits in bi_buf.  All bits above the last valid bit
  255      * are always zero.
  256      */
  257 
  258 } FAR deflate_state;
  259 
  260 /* Output a byte on the stream.
  261  * IN assertion: there is enough room in pending_buf.
  262  */
  263 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
  264 
  265 
  266 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
  267 /* Minimum amount of lookahead, except at the end of the input file.
  268  * See deflate.c for comments about the MIN_MATCH+1.
  269  */
  270 
  271 #define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD)
  272 /* In order to simplify the code, particularly on 16 bit machines, match
  273  * distances are limited to MAX_DIST instead of WSIZE.
  274  */
  275 
  276         /* in trees.c */
  277 void _tr_init         OF((deflate_state *s));
  278 int  _tr_tally        OF((deflate_state *s, unsigned dist, unsigned lc));
  279 void _tr_flush_block  OF((deflate_state *s, charf *buf, ulg stored_len,
  280                           int eof));
  281 void _tr_align        OF((deflate_state *s));
  282 void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,
  283                           int eof));
  284 
  285 #define d_code(dist) \
  286    ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
  287 /* Mapping from a distance to a distance code. dist is the distance - 1 and
  288  * must not have side effects. _dist_code[256] and _dist_code[257] are never
  289  * used.
  290  */
  291 
  292 #ifndef DEBUG
  293 /* Inline versions of _tr_tally for speed: */
  294 
  295 #if defined(GEN_TREES_H) || !defined(STDC)
  296   extern uch _length_code[];
  297   extern uch _dist_code[];
  298 #else
  299   extern const uch _length_code[];
  300   extern const uch _dist_code[];
  301 #endif
  302 
  303 # define _tr_tally_lit(s, c, flush) \
  304   { uch cc = (c); \
  305     s->d_buf[s->last_lit] = 0; \
  306     s->l_buf[s->last_lit++] = cc; \
  307     s->dyn_ltree[cc].Freq++; \
  308     flush = (s->last_lit == s->lit_bufsize-1); \
  309    }
  310 # define _tr_tally_dist(s, distance, length, flush) \
  311   { uch len = (length); \
  312     ush dist = (distance); \
  313     s->d_buf[s->last_lit] = dist; \
  314     s->l_buf[s->last_lit++] = len; \
  315     dist--; \
  316     s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
  317     s->dyn_dtree[d_code(dist)].Freq++; \
  318     flush = (s->last_lit == s->lit_bufsize-1); \
  319   }
  320 #else
  321 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
  322 # define _tr_tally_dist(s, distance, length, flush) \
  323               flush = _tr_tally(s, distance, length)
  324 #endif
  325 
  326 #endif /* DEFLATE_H */