zlib/infutil.c

   1 /* inflate_util.c -- data and routines common to blocks and codes
   2  * Copyright (C) 1995-1998 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include "zutil.h"
   7 #include "infblock.h"
   8 #include "inftrees.h"
   9 #include "infcodes.h"
  10 #include "infutil.h"
  11
  12 struct inflate_codes_state {int dummy;}; /* for buggy compilers */
  13
  14 /* And'ing with mask[n] masks the lower n bits */
  15 uInt inflate_mask[17] = {
  16     0x0000,
  17     0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
  18     0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
  19 };
  20
  21
  22 /* copy as much as possible from the sliding window to the output area */
  23 int inflate_flush(s, z, r)
  24 inflate_blocks_statef *s;
  25 z_streamp z;
  26 int r;
  27 {
  28   uInt n;
  29   Bytef *p;
  30   Bytef *q;
  31
  32   /* local copies of source and destination pointers */
  33   p = z->next_out;
  34   q = s->read;
  35
  36   /* compute number of bytes to copy as far as end of window */
  37   n = (uInt)((q <= s->write ? s->write : s->end) - q);
  38   if (n > z->avail_out) n = z->avail_out;
  39   if (n && r == Z_BUF_ERROR) r = Z_OK;
  40
  41   /* update counters */
  42   z->avail_out -= n;
  43   z->total_out += n;
  44
  45   /* update check information */
  46   if (s->checkfn != Z_NULL)
  47     z->adler = s->check = (*s->checkfn)(s->check, q, n);
  48
  49   /* copy as far as end of window */
  50   zmemcpy(p, q, n);
  51   p += n;
  52   q += n;
  53
  54   /* see if more to copy at beginning of window */
  55   if (q == s->end)
  56   {
  57     /* wrap pointers */
  58     q = s->window;
  59     if (s->write == s->end)
  60       s->write = s->window;
  61
  62     /* compute bytes to copy */
  63     n = (uInt)(s->write - q);
  64     if (n > z->avail_out) n = z->avail_out;
  65     if (n && r == Z_BUF_ERROR) r = Z_OK;
  66
  67     /* update counters */
  68     z->avail_out -= n;
  69     z->total_out += n;
  70
  71     /* update check information */
  72     if (s->checkfn != Z_NULL)
  73       z->adler = s->check = (*s->checkfn)(s->check, q, n);
  74
  75     /* copy */
  76     zmemcpy(p, q, n);
  77     p += n;
  78     q += n;
  79   }
  80
  81   /* update pointers */
  82   z->next_out = p;
  83   s->read = q;
  84
  85   /* done */
  86   return r;
  87 }