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 }