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Member "tvnserver-2.0.4/zlib/deflate.h" (23 Nov 2009, 11925 Bytes) of archive /windows/misc/tvnserver-2.0.4-src.zip:


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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 /* ===========================================================================
   19  * Internal compression state.
   20  */
   21 
   22 #define LENGTH_CODES 29
   23 /* number of length codes, not counting the special END_BLOCK code */
   24 
   25 #define LITERALS  256
   26 /* number of literal bytes 0..255 */
   27 
   28 #define L_CODES (LITERALS+1+LENGTH_CODES)
   29 /* number of Literal or Length codes, including the END_BLOCK code */
   30 
   31 #define D_CODES   30
   32 /* number of distance codes */
   33 
   34 #define BL_CODES  19
   35 /* number of codes used to transfer the bit lengths */
   36 
   37 #define HEAP_SIZE (2*L_CODES+1)
   38 /* maximum heap size */
   39 
   40 #define MAX_BITS 15
   41 /* All codes must not exceed MAX_BITS bits */
   42 
   43 #define INIT_STATE    42
   44 #define BUSY_STATE   113
   45 #define FINISH_STATE 666
   46 /* Stream status */
   47 
   48 
   49 /* Data structure describing a single value and its code string. */
   50 typedef struct ct_data_s {
   51     union {
   52         ush  freq;       /* frequency count */
   53         ush  code;       /* bit string */
   54     } fc;
   55     union {
   56         ush  dad;        /* father node in Huffman tree */
   57         ush  len;        /* length of bit string */
   58     } dl;
   59 } FAR ct_data;
   60 
   61 #define Freq fc.freq
   62 #define Code fc.code
   63 #define Dad  dl.dad
   64 #define Len  dl.len
   65 
   66 typedef struct static_tree_desc_s  static_tree_desc;
   67 
   68 typedef struct tree_desc_s {
   69     ct_data *dyn_tree;           /* the dynamic tree */
   70     int     max_code;            /* largest code with non zero frequency */
   71     static_tree_desc *stat_desc; /* the corresponding static tree */
   72 } FAR tree_desc;
   73 
   74 typedef ush Pos;
   75 typedef Pos FAR Posf;
   76 typedef unsigned IPos;
   77 
   78 /* A Pos is an index in the character window. We use short instead of int to
   79  * save space in the various tables. IPos is used only for parameter passing.
   80  */
   81 
   82 typedef struct internal_state {
   83     z_streamp strm;      /* pointer back to this zlib stream */
   84     int   status;        /* as the name implies */
   85     Bytef *pending_buf;  /* output still pending */
   86     ulg   pending_buf_size; /* size of pending_buf */
   87     Bytef *pending_out;  /* next pending byte to output to the stream */
   88     int   pending;       /* nb of bytes in the pending buffer */
   89     int   noheader;      /* suppress zlib header and adler32 */
   90     Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
   91     Byte  method;        /* STORED (for zip only) or DEFLATED */
   92     int   last_flush;    /* value of flush param for previous deflate call */
   93 
   94                 /* used by deflate.c: */
   95 
   96     uInt  w_size;        /* LZ77 window size (32K by default) */
   97     uInt  w_bits;        /* log2(w_size)  (8..16) */
   98     uInt  w_mask;        /* w_size - 1 */
   99 
  100     Bytef *window;
  101     /* Sliding window. Input bytes are read into the second half of the window,
  102      * and move to the first half later to keep a dictionary of at least wSize
  103      * bytes. With this organization, matches are limited to a distance of
  104      * wSize-MAX_MATCH bytes, but this ensures that IO is always
  105      * performed with a length multiple of the block size. Also, it limits
  106      * the window size to 64K, which is quite useful on MSDOS.
  107      * To do: use the user input buffer as sliding window.
  108      */
  109 
  110     ulg window_size;
  111     /* Actual size of window: 2*wSize, except when the user input buffer
  112      * is directly used as sliding window.
  113      */
  114 
  115     Posf *prev;
  116     /* Link to older string with same hash index. To limit the size of this
  117      * array to 64K, this link is maintained only for the last 32K strings.
  118      * An index in this array is thus a window index modulo 32K.
  119      */
  120 
  121     Posf *head; /* Heads of the hash chains or NIL. */
  122 
  123     uInt  ins_h;          /* hash index of string to be inserted */
  124     uInt  hash_size;      /* number of elements in hash table */
  125     uInt  hash_bits;      /* log2(hash_size) */
  126     uInt  hash_mask;      /* hash_size-1 */
  127 
  128     uInt  hash_shift;
  129     /* Number of bits by which ins_h must be shifted at each input
  130      * step. It must be such that after MIN_MATCH steps, the oldest
  131      * byte no longer takes part in the hash key, that is:
  132      *   hash_shift * MIN_MATCH >= hash_bits
  133      */
  134 
  135     long block_start;
  136     /* Window position at the beginning of the current output block. Gets
  137      * negative when the window is moved backwards.
  138      */
  139 
  140     uInt match_length;           /* length of best match */
  141     IPos prev_match;             /* previous match */
  142     int match_available;         /* set if previous match exists */
  143     uInt strstart;               /* start of string to insert */
  144     uInt match_start;            /* start of matching string */
  145     uInt lookahead;              /* number of valid bytes ahead in window */
  146 
  147     uInt prev_length;
  148     /* Length of the best match at previous step. Matches not greater than this
  149      * are discarded. This is used in the lazy match evaluation.
  150      */
  151 
  152     uInt max_chain_length;
  153     /* To speed up deflation, hash chains are never searched beyond this
  154      * length.  A higher limit improves compression ratio but degrades the
  155      * speed.
  156      */
  157 
  158     uInt max_lazy_match;
  159     /* Attempt to find a better match only when the current match is strictly
  160      * smaller than this value. This mechanism is used only for compression
  161      * levels >= 4.
  162      */
  163 #   define max_insert_length  max_lazy_match
  164     /* Insert new strings in the hash table only if the match length is not
  165      * greater than this length. This saves time but degrades compression.
  166      * max_insert_length is used only for compression levels <= 3.
  167      */
  168 
  169     int level;    /* compression level (1..9) */
  170     int strategy; /* favor or force Huffman coding*/
  171 
  172     uInt good_match;
  173     /* Use a faster search when the previous match is longer than this */
  174 
  175     int nice_match; /* Stop searching when current match exceeds this */
  176 
  177                 /* used by trees.c: */
  178     /* Didn't use ct_data typedef below to supress compiler warning */
  179     struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
  180     struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
  181     struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */
  182 
  183     struct tree_desc_s l_desc;               /* desc. for literal tree */
  184     struct tree_desc_s d_desc;               /* desc. for distance tree */
  185     struct tree_desc_s bl_desc;              /* desc. for bit length tree */
  186 
  187     ush bl_count[MAX_BITS+1];
  188     /* number of codes at each bit length for an optimal tree */
  189 
  190     int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
  191     int heap_len;               /* number of elements in the heap */
  192     int heap_max;               /* element of largest frequency */
  193     /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
  194      * The same heap array is used to build all trees.
  195      */
  196 
  197     uch depth[2*L_CODES+1];
  198     /* Depth of each subtree used as tie breaker for trees of equal frequency
  199      */
  200 
  201     uchf *l_buf;          /* buffer for literals or lengths */
  202 
  203     uInt  lit_bufsize;
  204     /* Size of match buffer for literals/lengths.  There are 4 reasons for
  205      * limiting lit_bufsize to 64K:
  206      *   - frequencies can be kept in 16 bit counters
  207      *   - if compression is not successful for the first block, all input
  208      *     data is still in the window so we can still emit a stored block even
  209      *     when input comes from standard input.  (This can also be done for
  210      *     all blocks if lit_bufsize is not greater than 32K.)
  211      *   - if compression is not successful for a file smaller than 64K, we can
  212      *     even emit a stored file instead of a stored block (saving 5 bytes).
  213      *     This is applicable only for zip (not gzip or zlib).
  214      *   - creating new Huffman trees less frequently may not provide fast
  215      *     adaptation to changes in the input data statistics. (Take for
  216      *     example a binary file with poorly compressible code followed by
  217      *     a highly compressible string table.) Smaller buffer sizes give
  218      *     fast adaptation but have of course the overhead of transmitting
  219      *     trees more frequently.
  220      *   - I can't count above 4
  221      */
  222 
  223     uInt last_lit;      /* running index in l_buf */
  224 
  225     ushf *d_buf;
  226     /* Buffer for distances. To simplify the code, d_buf and l_buf have
  227      * the same number of elements. To use different lengths, an extra flag
  228      * array would be necessary.
  229      */
  230 
  231     ulg opt_len;        /* bit length of current block with optimal trees */
  232     ulg static_len;     /* bit length of current block with static trees */
  233     uInt matches;       /* number of string matches in current block */
  234     int last_eob_len;   /* bit length of EOB code for last block */
  235 
  236 #ifdef DEBUG
  237     ulg compressed_len; /* total bit length of compressed file mod 2^32 */
  238     ulg bits_sent;      /* bit length of compressed data sent mod 2^32 */
  239 #endif
  240 
  241     ush bi_buf;
  242     /* Output buffer. bits are inserted starting at the bottom (least
  243      * significant bits).
  244      */
  245     int bi_valid;
  246     /* Number of valid bits in bi_buf.  All bits above the last valid bit
  247      * are always zero.
  248      */
  249 
  250 } FAR deflate_state;
  251 
  252 /* Output a byte on the stream.
  253  * IN assertion: there is enough room in pending_buf.
  254  */
  255 #define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
  256 
  257 
  258 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
  259 /* Minimum amount of lookahead, except at the end of the input file.
  260  * See deflate.c for comments about the MIN_MATCH+1.
  261  */
  262 
  263 #define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD)
  264 /* In order to simplify the code, particularly on 16 bit machines, match
  265  * distances are limited to MAX_DIST instead of WSIZE.
  266  */
  267 
  268         /* in trees.c */
  269 void _tr_init         OF((deflate_state *s));
  270 int  _tr_tally        OF((deflate_state *s, unsigned dist, unsigned lc));
  271 void _tr_flush_block  OF((deflate_state *s, charf *buf, ulg stored_len,
  272               int eof));
  273 void _tr_align        OF((deflate_state *s));
  274 void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,
  275                           int eof));
  276 
  277 #define d_code(dist) \
  278    ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])
  279 /* Mapping from a distance to a distance code. dist is the distance - 1 and
  280  * must not have side effects. _dist_code[256] and _dist_code[257] are never
  281  * used.
  282  */
  283 
  284 #ifndef DEBUG
  285 /* Inline versions of _tr_tally for speed: */
  286 
  287 #if defined(GEN_TREES_H) || !defined(STDC)
  288   extern uch _length_code[];
  289   extern uch _dist_code[];
  290 #else
  291   extern const uch _length_code[];
  292   extern const uch _dist_code[];
  293 #endif
  294 
  295 # define _tr_tally_lit(s, c, flush) \
  296   { uch cc = (c); \
  297     s->d_buf[s->last_lit] = 0; \
  298     s->l_buf[s->last_lit++] = cc; \
  299     s->dyn_ltree[cc].Freq++; \
  300     flush = (s->last_lit == s->lit_bufsize-1); \
  301    }
  302 # define _tr_tally_dist(s, distance, length, flush) \
  303   { uch len = (length); \
  304     ush dist = (distance); \
  305     s->d_buf[s->last_lit] = dist; \
  306     s->l_buf[s->last_lit++] = len; \
  307     dist--; \
  308     s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
  309     s->dyn_dtree[d_code(dist)].Freq++; \
  310     flush = (s->last_lit == s->lit_bufsize-1); \
  311   }
  312 #else
  313 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
  314 # define _tr_tally_dist(s, distance, length, flush) \
  315               flush = _tr_tally(s, distance, length) 
  316 #endif
  317 
  318 #endif