linux/lib/zlib_deflate/defutil.h
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   4#define Assert(err, str) 
   5#define Trace(dummy) 
   6#define Tracev(dummy) 
   7#define Tracecv(err, dummy) 
   8#define Tracevv(dummy) 
   9
  10
  11
  12#define LENGTH_CODES 29
  13/* number of length codes, not counting the special END_BLOCK code */
  14
  15#define LITERALS  256
  16/* number of literal bytes 0..255 */
  17
  18#define L_CODES (LITERALS+1+LENGTH_CODES)
  19/* number of Literal or Length codes, including the END_BLOCK code */
  20
  21#define D_CODES   30
  22/* number of distance codes */
  23
  24#define BL_CODES  19
  25/* number of codes used to transfer the bit lengths */
  26
  27#define HEAP_SIZE (2*L_CODES+1)
  28/* maximum heap size */
  29
  30#define MAX_BITS 15
  31/* All codes must not exceed MAX_BITS bits */
  32
  33#define INIT_STATE    42
  34#define BUSY_STATE   113
  35#define FINISH_STATE 666
  36/* Stream status */
  37
  38
  39/* Data structure describing a single value and its code string. */
  40typedef struct ct_data_s {
  41    union {
  42        ush  freq;       /* frequency count */
  43        ush  code;       /* bit string */
  44    } fc;
  45    union {
  46        ush  dad;        /* father node in Huffman tree */
  47        ush  len;        /* length of bit string */
  48    } dl;
  49} ct_data;
  50
  51#define Freq fc.freq
  52#define Code fc.code
  53#define Dad  dl.dad
  54#define Len  dl.len
  55
  56typedef struct static_tree_desc_s  static_tree_desc;
  57
  58typedef struct tree_desc_s {
  59    ct_data *dyn_tree;           /* the dynamic tree */
  60    int     max_code;            /* largest code with non zero frequency */
  61    static_tree_desc *stat_desc; /* the corresponding static tree */
  62} tree_desc;
  63
  64typedef ush Pos;
  65typedef unsigned IPos;
  66
  67/* A Pos is an index in the character window. We use short instead of int to
  68 * save space in the various tables. IPos is used only for parameter passing.
  69 */
  70
  71typedef struct deflate_state {
  72    z_streamp strm;      /* pointer back to this zlib stream */
  73    int   status;        /* as the name implies */
  74    Byte *pending_buf;   /* output still pending */
  75    ulg   pending_buf_size; /* size of pending_buf */
  76    Byte *pending_out;   /* next pending byte to output to the stream */
  77    int   pending;       /* nb of bytes in the pending buffer */
  78    int   noheader;      /* suppress zlib header and adler32 */
  79    Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
  80    Byte  method;        /* STORED (for zip only) or DEFLATED */
  81    int   last_flush;    /* value of flush param for previous deflate call */
  82
  83                /* used by deflate.c: */
  84
  85    uInt  w_size;        /* LZ77 window size (32K by default) */
  86    uInt  w_bits;        /* log2(w_size)  (8..16) */
  87    uInt  w_mask;        /* w_size - 1 */
  88
  89    Byte *window;
  90    /* Sliding window. Input bytes are read into the second half of the window,
  91     * and move to the first half later to keep a dictionary of at least wSize
  92     * bytes. With this organization, matches are limited to a distance of
  93     * wSize-MAX_MATCH bytes, but this ensures that IO is always
  94     * performed with a length multiple of the block size. Also, it limits
  95     * the window size to 64K, which is quite useful on MSDOS.
  96     * To do: use the user input buffer as sliding window.
  97     */
  98
  99    ulg window_size;
 100    /* Actual size of window: 2*wSize, except when the user input buffer
 101     * is directly used as sliding window.
 102     */
 103
 104    Pos *prev;
 105    /* Link to older string with same hash index. To limit the size of this
 106     * array to 64K, this link is maintained only for the last 32K strings.
 107     * An index in this array is thus a window index modulo 32K.
 108     */
 109
 110    Pos *head; /* Heads of the hash chains or NIL. */
 111
 112    uInt  ins_h;          /* hash index of string to be inserted */
 113    uInt  hash_size;      /* number of elements in hash table */
 114    uInt  hash_bits;      /* log2(hash_size) */
 115    uInt  hash_mask;      /* hash_size-1 */
 116
 117    uInt  hash_shift;
 118    /* Number of bits by which ins_h must be shifted at each input
 119     * step. It must be such that after MIN_MATCH steps, the oldest
 120     * byte no longer takes part in the hash key, that is:
 121     *   hash_shift * MIN_MATCH >= hash_bits
 122     */
 123
 124    long block_start;
 125    /* Window position at the beginning of the current output block. Gets
 126     * negative when the window is moved backwards.
 127     */
 128
 129    uInt match_length;           /* length of best match */
 130    IPos prev_match;             /* previous match */
 131    int match_available;         /* set if previous match exists */
 132    uInt strstart;               /* start of string to insert */
 133    uInt match_start;            /* start of matching string */
 134    uInt lookahead;              /* number of valid bytes ahead in window */
 135
 136    uInt prev_length;
 137    /* Length of the best match at previous step. Matches not greater than this
 138     * are discarded. This is used in the lazy match evaluation.
 139     */
 140
 141    uInt max_chain_length;
 142    /* To speed up deflation, hash chains are never searched beyond this
 143     * length.  A higher limit improves compression ratio but degrades the
 144     * speed.
 145     */
 146
 147    uInt max_lazy_match;
 148    /* Attempt to find a better match only when the current match is strictly
 149     * smaller than this value. This mechanism is used only for compression
 150     * levels >= 4.
 151     */
 152#   define max_insert_length  max_lazy_match
 153    /* Insert new strings in the hash table only if the match length is not
 154     * greater than this length. This saves time but degrades compression.
 155     * max_insert_length is used only for compression levels <= 3.
 156     */
 157
 158    int level;    /* compression level (1..9) */
 159    int strategy; /* favor or force Huffman coding*/
 160
 161    uInt good_match;
 162    /* Use a faster search when the previous match is longer than this */
 163
 164    int nice_match; /* Stop searching when current match exceeds this */
 165
 166                /* used by trees.c: */
 167    /* Didn't use ct_data typedef below to suppress compiler warning */
 168    struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
 169    struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
 170    struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */
 171
 172    struct tree_desc_s l_desc;               /* desc. for literal tree */
 173    struct tree_desc_s d_desc;               /* desc. for distance tree */
 174    struct tree_desc_s bl_desc;              /* desc. for bit length tree */
 175
 176    ush bl_count[MAX_BITS+1];
 177    /* number of codes at each bit length for an optimal tree */
 178
 179    int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
 180    int heap_len;               /* number of elements in the heap */
 181    int heap_max;               /* element of largest frequency */
 182    /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
 183     * The same heap array is used to build all trees.
 184     */
 185
 186    uch depth[2*L_CODES+1];
 187    /* Depth of each subtree used as tie breaker for trees of equal frequency
 188     */
 189
 190    uch *l_buf;          /* buffer for literals or lengths */
 191
 192    uInt  lit_bufsize;
 193    /* Size of match buffer for literals/lengths.  There are 4 reasons for
 194     * limiting lit_bufsize to 64K:
 195     *   - frequencies can be kept in 16 bit counters
 196     *   - if compression is not successful for the first block, all input
 197     *     data is still in the window so we can still emit a stored block even
 198     *     when input comes from standard input.  (This can also be done for
 199     *     all blocks if lit_bufsize is not greater than 32K.)
 200     *   - if compression is not successful for a file smaller than 64K, we can
 201     *     even emit a stored file instead of a stored block (saving 5 bytes).
 202     *     This is applicable only for zip (not gzip or zlib).
 203     *   - creating new Huffman trees less frequently may not provide fast
 204     *     adaptation to changes in the input data statistics. (Take for
 205     *     example a binary file with poorly compressible code followed by
 206     *     a highly compressible string table.) Smaller buffer sizes give
 207     *     fast adaptation but have of course the overhead of transmitting
 208     *     trees more frequently.
 209     *   - I can't count above 4
 210     */
 211
 212    uInt last_lit;      /* running index in l_buf */
 213
 214    ush *d_buf;
 215    /* Buffer for distances. To simplify the code, d_buf and l_buf have
 216     * the same number of elements. To use different lengths, an extra flag
 217     * array would be necessary.
 218     */
 219
 220    ulg opt_len;        /* bit length of current block with optimal trees */
 221    ulg static_len;     /* bit length of current block with static trees */
 222    ulg compressed_len; /* total bit length of compressed file */
 223    uInt matches;       /* number of string matches in current block */
 224    int last_eob_len;   /* bit length of EOB code for last block */
 225
 226#ifdef DEBUG_ZLIB
 227    ulg bits_sent;      /* bit length of the compressed data */
 228#endif
 229
 230    ush bi_buf;
 231    /* Output buffer. bits are inserted starting at the bottom (least
 232     * significant bits).
 233     */
 234    int bi_valid;
 235    /* Number of valid bits in bi_buf.  All bits above the last valid bit
 236     * are always zero.
 237     */
 238
 239} deflate_state;
 240
 241typedef struct deflate_workspace {
 242    /* State memory for the deflator */
 243    deflate_state deflate_memory;
 244    Byte *window_memory;
 245    Pos *prev_memory;
 246    Pos *head_memory;
 247    char *overlay_memory;
 248} deflate_workspace;
 249
 250#define zlib_deflate_window_memsize(windowBits) \
 251        (2 * (1 << (windowBits)) * sizeof(Byte))
 252#define zlib_deflate_prev_memsize(windowBits) \
 253        ((1 << (windowBits)) * sizeof(Pos))
 254#define zlib_deflate_head_memsize(memLevel) \
 255        ((1 << ((memLevel)+7)) * sizeof(Pos))
 256#define zlib_deflate_overlay_memsize(memLevel) \
 257        ((1 << ((memLevel)+6)) * (sizeof(ush)+2))
 258
 259/* Output a byte on the stream.
 260 * IN assertion: there is enough room in pending_buf.
 261 */
 262#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}
 263
 264
 265#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
 266/* Minimum amount of lookahead, except at the end of the input file.
 267 * See deflate.c for comments about the MIN_MATCH+1.
 268 */
 269
 270#define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD)
 271/* In order to simplify the code, particularly on 16 bit machines, match
 272 * distances are limited to MAX_DIST instead of WSIZE.
 273 */
 274
 275        /* in trees.c */
 276void zlib_tr_init         (deflate_state *s);
 277int  zlib_tr_tally        (deflate_state *s, unsigned dist, unsigned lc);
 278ulg  zlib_tr_flush_block  (deflate_state *s, char *buf, ulg stored_len,
 279                           int eof);
 280void zlib_tr_align        (deflate_state *s);
 281void zlib_tr_stored_block (deflate_state *s, char *buf, ulg stored_len,
 282                           int eof);
 283void zlib_tr_stored_type_only (deflate_state *);
 284
 285
 286/* ===========================================================================
 287 * Output a short LSB first on the stream.
 288 * IN assertion: there is enough room in pendingBuf.
 289 */
 290#define put_short(s, w) { \
 291    put_byte(s, (uch)((w) & 0xff)); \
 292    put_byte(s, (uch)((ush)(w) >> 8)); \
 293}
 294
 295/* ===========================================================================
 296 * Reverse the first len bits of a code, using straightforward code (a faster
 297 * method would use a table)
 298 * IN assertion: 1 <= len <= 15
 299 */
 300static inline unsigned bi_reverse(unsigned code, /* the value to invert */
 301                                  int len)       /* its bit length */
 302{
 303    register unsigned res = 0;
 304    do {
 305        res |= code & 1;
 306        code >>= 1, res <<= 1;
 307    } while (--len > 0);
 308    return res >> 1;
 309}
 310
 311/* ===========================================================================
 312 * Flush the bit buffer, keeping at most 7 bits in it.
 313 */
 314static inline void bi_flush(deflate_state *s)
 315{
 316    if (s->bi_valid == 16) {
 317        put_short(s, s->bi_buf);
 318        s->bi_buf = 0;
 319        s->bi_valid = 0;
 320    } else if (s->bi_valid >= 8) {
 321        put_byte(s, (Byte)s->bi_buf);
 322        s->bi_buf >>= 8;
 323        s->bi_valid -= 8;
 324    }
 325}
 326
 327/* ===========================================================================
 328 * Flush the bit buffer and align the output on a byte boundary
 329 */
 330static inline void bi_windup(deflate_state *s)
 331{
 332    if (s->bi_valid > 8) {
 333        put_short(s, s->bi_buf);
 334    } else if (s->bi_valid > 0) {
 335        put_byte(s, (Byte)s->bi_buf);
 336    }
 337    s->bi_buf = 0;
 338    s->bi_valid = 0;
 339#ifdef DEBUG_ZLIB
 340    s->bits_sent = (s->bits_sent+7) & ~7;
 341#endif
 342}
 343
 344
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