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Annotation of embedaddon/rsync/zlib/inftrees.h, revision 1.1.1.2

1.1       misho       1: /* inftrees.h -- header to use inftrees.c
1.1.1.2 ! misho       2:  * Copyright (C) 1995-2005, 2010 Mark Adler
1.1       misho       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: /* Structure for decoding tables.  Each entry provides either the
                     12:    information needed to do the operation requested by the code that
                     13:    indexed that table entry, or it provides a pointer to another
                     14:    table that indexes more bits of the code.  op indicates whether
                     15:    the entry is a pointer to another table, a literal, a length or
                     16:    distance, an end-of-block, or an invalid code.  For a table
                     17:    pointer, the low four bits of op is the number of index bits of
                     18:    that table.  For a length or distance, the low four bits of op
                     19:    is the number of extra bits to get after the code.  bits is
                     20:    the number of bits in this code or part of the code to drop off
                     21:    of the bit buffer.  val is the actual byte to output in the case
                     22:    of a literal, the base length or distance, or the offset from
                     23:    the current table to the next table.  Each entry is four bytes. */
                     24: typedef struct {
                     25:     unsigned char op;           /* operation, extra bits, table bits */
                     26:     unsigned char bits;         /* bits in this part of the code */
                     27:     unsigned short val;         /* offset in table or code value */
                     28: } code;
                     29: 
                     30: /* op values as set by inflate_table():
                     31:     00000000 - literal
                     32:     0000tttt - table link, tttt != 0 is the number of table index bits
                     33:     0001eeee - length or distance, eeee is the number of extra bits
                     34:     01100000 - end of block
                     35:     01000000 - invalid code
                     36:  */
                     37: 
1.1.1.2 ! misho      38: /* Maximum size of the dynamic table.  The maximum number of code structures is
        !            39:    1444, which is the sum of 852 for literal/length codes and 592 for distance
        !            40:    codes.  These values were found by exhaustive searches using the program
        !            41:    examples/enough.c found in the zlib distribtution.  The arguments to that
        !            42:    program are the number of symbols, the initial root table size, and the
        !            43:    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
        !            44:    returns returns 852, and "enough 30 6 15" for distance codes returns 592.
        !            45:    The initial root table size (9 or 6) is found in the fifth argument of the
        !            46:    inflate_table() calls in inflate.c and infback.c.  If the root table size is
        !            47:    changed, then these maximum sizes would be need to be recalculated and
        !            48:    updated. */
        !            49: #define ENOUGH_LENS 852
        !            50: #define ENOUGH_DISTS 592
        !            51: #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
1.1       misho      52: 
1.1.1.2 ! misho      53: /* Type of code to build for inflate_table() */
1.1       misho      54: typedef enum {
                     55:     CODES,
                     56:     LENS,
                     57:     DISTS
                     58: } codetype;
                     59: 
1.1.1.2 ! misho      60: int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens,
1.1       misho      61:                              unsigned codes, code FAR * FAR *table,
                     62:                              unsigned FAR *bits, unsigned short FAR *work));