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  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.  
  13. /* And'ing with mask[n] masks the lower n bits */
  14. local const uInt inflate_mask[17] = {
  15.     0x0000,
  16.     0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
  17.     0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
  18. };
  19.  
  20.  
  21. /* copy as much as possible from the sliding window to the output area */
  22. local int inflate_flush( /* s, z, r) */
  23. inflate_blocks_statef *s,
  24. z_streamp z,
  25. int r )
  26. {
  27.   uInt n;
  28.   Bytef *p;
  29.   Bytef *q;
  30.  
  31.   /* local copies of source and destination pointers */
  32.   p = z->next_out;
  33.   q = s->read;
  34.  
  35.   /* compute number of bytes to copy as far as end of window */
  36.   n = (uInt)((q <= s->write ? s->write : s->end) - q);
  37.   if (n > z->avail_out) n = z->avail_out;
  38.   if (n && r == Z_BUF_ERROR) r = Z_OK;
  39.  
  40.   /* update counters */
  41.   z->avail_out -= n;
  42.   z->total_out += n;
  43.  
  44.   /* update check information */
  45.   if (s->checkfn != Z_NULL)
  46.     z->adler = s->check = (*s->checkfn)(s->check, q, n);
  47.  
  48.   /* copy as far as end of window */
  49.   zmemcpy(p, q, n);
  50.   p += n;
  51.   q += n;
  52.  
  53.   /* see if more to copy at beginning of window */
  54.   if (q == s->end)
  55.   {
  56.     /* wrap pointers */
  57.     q = s->window;
  58.     if (s->write == s->end)
  59.       s->write = s->window;
  60.  
  61.     /* compute bytes to copy */
  62.     n = (uInt)(s->write - q);
  63.     if (n > z->avail_out) n = z->avail_out;
  64.     if (n && r == Z_BUF_ERROR) r = Z_OK;
  65.  
  66.     /* update counters */
  67.     z->avail_out -= n;
  68.     z->total_out += n;
  69.  
  70.     /* update check information */
  71.     if (s->checkfn != Z_NULL)
  72.       z->adler = s->check = (*s->checkfn)(s->check, q, n);
  73.  
  74.     /* copy */
  75.     zmemcpy(p, q, n);
  76.     p += n;
  77.     q += n;
  78.   }
  79.  
  80.   /* update pointers */
  81.   z->next_out = p;
  82.   s->read = q;
  83.  
  84.   /* done */
  85.   return r;
  86. }
  87.