src/zlib/infutil.c

   1 /* inflate_util.c -- data and routines common to blocks and codes
   2  * Copyright (C) 1995-2002 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 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  24 int inflate_flush(inflate_blocks_statef* s, z_streamp z, int r)
  25 #else
  26 int inflate_flush(s, z, r)
  27 inflate_blocks_statef *s;
  28 z_streamp z;
  29 int r;
  30 #endif
  31 {
  32   uInt n;
  33   Bytef *p;
  34   Bytef *q;
  35
  36   /* local copies of source and destination pointers */
  37   p = z->next_out;
  38   q = s->read;
  39
  40   /* compute number of bytes to copy as far as end of window */
  41   n = (uInt)((q <= s->write ? s->write : s->end) - q);
  42   if (n > z->avail_out) n = z->avail_out;
  43   if (n && r == Z_BUF_ERROR) r = Z_OK;
  44
  45   /* update counters */
  46   z->avail_out -= n;
  47   z->total_out += n;
  48
  49   /* update check information */
  50   if (s->checkfn != Z_NULL)
  51     z->adler = s->check = (*s->checkfn)(s->check, q, n);
  52
  53   /* copy as far as end of window */
  54   zmemcpy(p, q, n);
  55   p += n;
  56   q += n;
  57
  58   /* see if more to copy at beginning of window */
  59   if (q == s->end)
  60   {
  61     /* wrap pointers */
  62     q = s->window;
  63     if (s->write == s->end)
  64       s->write = s->window;
  65
  66     /* compute bytes to copy */
  67     n = (uInt)(s->write - q);
  68     if (n > z->avail_out) n = z->avail_out;
  69     if (n && r == Z_BUF_ERROR) r = Z_OK;
  70
  71     /* update counters */
  72     z->avail_out -= n;
  73     z->total_out += n;
  74
  75     /* update check information */
  76     if (s->checkfn != Z_NULL)
  77       z->adler = s->check = (*s->checkfn)(s->check, q, n);
  78
  79     /* copy */
  80     zmemcpy(p, q, n);
  81     p += n;
  82     q += n;
  83   }
  84
  85   /* update pointers */
  86   z->next_out = p;
  87   s->read = q;
  88
  89   /* done */
  90   return r;
  91 }