1 /**************************************************************************
3 * Copyright 2013-2014 RAD Game Tools and Valve Software
4 * Copyright 2010-2014 Rich Geldreich and Tenacious Software LLC
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 **************************************************************************/
27 // File: vogl_checksum.cpp
28 #include "vogl_core.h"
32 // From the public domain stb.h header.
33 uint adler32(const void *pBuf, size_t buflen, uint adler32)
35 const uint8 *buffer = static_cast<const uint8 *>(pBuf);
37 const unsigned long ADLER_MOD = 65521;
38 unsigned long s1 = adler32 & 0xffff, s2 = adler32 >> 16;
42 blocklen = buflen % 5552;
45 for (i = 0; i + 7 < blocklen; i += 8)
47 s1 += buffer[0], s2 += s1;
48 s1 += buffer[1], s2 += s1;
49 s1 += buffer[2], s2 += s1;
50 s1 += buffer[3], s2 += s1;
51 s1 += buffer[4], s2 += s1;
52 s1 += buffer[5], s2 += s1;
53 s1 += buffer[6], s2 += s1;
54 s1 += buffer[7], s2 += s1;
59 for (; i < blocklen; ++i)
60 s1 += *buffer++, s2 += s1;
62 s1 %= ADLER_MOD, s2 %= ADLER_MOD;
66 return static_cast<uint>((s2 << 16) + s1);
69 uint16 crc16(const void *pBuf, size_t len, uint16 crc)
73 const uint8 *p = reinterpret_cast<const uint8 *>(pBuf);
76 const uint16 q = *p++ ^ (crc >> 8);
78 uint16 r = (q >> 4) ^ q;
87 return static_cast<uint16>(~crc);