apps/plugins/imageviewer/png/tinfzlib.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Original source:
  11  * Copyright (c) 2003 by Joergen Ibsen / Jibz
  12  *
  13  * Rockbox adaptation:
  14  * Copyright (c) 2010 by Marcin Bukat
  15  *
  16  * This program is free software; you can redistribute it and/or
  17  * modify it under the terms of the GNU General Public License
  18  * as published by the Free Software Foundation; either version 2
  19  * of the License, or (at your option) any later version.
  20  *
  21  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  22  * KIND, either express or implied.
  23  *
  24  ****************************************************************************/
  25
  26 /*
  27  * tinfzlib  -  tiny zlib decompressor
  28  *
  29  * Copyright (c) 2003 by Joergen Ibsen / Jibz
  30  * All Rights Reserved
  31  *
  32  * http://www.ibsensoftware.com/
  33  *
  34  * This software is provided 'as-is', without any express
  35  * or implied warranty.  In no event will the authors be
  36  * held liable for any damages arising from the use of
  37  * this software.
  38  *
  39  * Permission is granted to anyone to use this software
  40  * for any purpose, including commercial applications,
  41  * and to alter it and redistribute it freely, subject to
  42  * the following restrictions:
  43  *
  44  * 1. The origin of this software must not be
  45  *    misrepresented; you must not claim that you
  46  *    wrote the original software. If you use this
  47  *    software in a product, an acknowledgment in
  48  *    the product documentation would be appreciated
  49  *    but is not required.
  50  *
  51  * 2. Altered source versions must be plainly marked
  52  *    as such, and must not be misrepresented as
  53  *    being the original software.
  54  *
  55  * 3. This notice may not be removed or altered from
  56  *    any source distribution.
  57  */
  58
  59 #include "tinf.h"
  60
  61 /* This routine do not check adler32 checksum
  62  * as it is tailored to be used as PNG decompressor
  63  * and PNG has crc32 check of the compressed block
  64  * already
  65  */
  66 int tinf_zlib_uncompress(void *dest, unsigned int *destLen,
  67                          const void *source, unsigned int sourceLen)
  68 {
  69    unsigned char *src = (unsigned char *)source;
  70    unsigned char *dst = (unsigned char *)dest;
  71    int res;
  72    unsigned char cmf, flg;
  73
  74    /* -- get header bytes -- */
  75
  76    cmf = src[0];
  77    flg = src[1];
  78
  79    /* -- check format -- */
  80
  81    /* check checksum */
  82    if (((cmf << 8) + flg) % 31) return TINF_DATA_ERROR;
  83
  84    /* check method is deflate */
  85    if ((cmf & 0x0f) != 8) return TINF_DATA_ERROR;
  86
  87    /* check window size is valid */
  88    if ((cmf >> 4) > 7) return TINF_DATA_ERROR;
  89
  90    /* check there is no preset dictionary */
  91    if (flg & 0x20) return TINF_DATA_ERROR;
  92
  93    /* -- inflate -- */
  94
  95    res = tinf_uncompress(dst, destLen, src + 2, sourceLen - 6);
  96
  97    if (res != TINF_OK) return TINF_DATA_ERROR;
  98
  99    return TINF_OK;
 100 }