76 lines
2.3 KiB
C
76 lines
2.3 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2021 James Buren (adaptations from tinf/zlib)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "adler32.h"
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#include "system.h"
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/* adler_32 (derived from tinf adler32 which was taken from zlib)
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* Adler-32 algorithm taken from the zlib source, which is
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* Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
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*/
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uint32_t adler_32(const void *src, uint32_t len, uint32_t adler32)
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{
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const unsigned char *buf = (const unsigned char *)src;
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uint32_t s1 = (adler32 & 0xffff);
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uint32_t s2 = (adler32 >> 16);
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enum {
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A32_BASE = 65521,
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A32_NMAX = 5552,
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};
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while (len > 0) {
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uint32_t k = MIN(len, A32_NMAX);
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uint32_t i;
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for (i = k / 16; i; --i, buf += 16) {
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s2 += s1 += buf[0];
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s2 += s1 += buf[1];
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s2 += s1 += buf[2];
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s2 += s1 += buf[3];
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s2 += s1 += buf[4];
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s2 += s1 += buf[5];
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s2 += s1 += buf[6];
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s2 += s1 += buf[7];
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s2 += s1 += buf[8];
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s2 += s1 += buf[9];
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s2 += s1 += buf[10];
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s2 += s1 += buf[11];
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s2 += s1 += buf[12];
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s2 += s1 += buf[13];
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s2 += s1 += buf[14];
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s2 += s1 += buf[15];
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}
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for (i = k % 16; i; --i) {
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s1 += *buf++;
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s2 += s1;
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}
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s1 %= A32_BASE;
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s2 %= A32_BASE;
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len -= k;
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}
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return (s1 | (s2 << 16));
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}
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