81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/*
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* Copyright (C) 2001 Nikos Mavroyanopoulos
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Library General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "libdefs.h"
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#if defined(ENABLE_ADLER32)
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#include "mhash_adler32.h"
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/* This is the implementation of Manuel Kasper <mk@neon1.net>.
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*/
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void mhash_clear_adler32(mutils_word32 *adler)
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{
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*adler = 0x1;
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}
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void mhash_get_adler32(__const mutils_word32 *adler, void *ret)
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{
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mutils_word32 tmp = *adler;
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#if defined(WORDS_BIGENDIAN)
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tmp = mutils_word32swap(tmp);
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#endif
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if (ret!=NULL)
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{
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mutils_memcpy(ret, &tmp, sizeof(mutils_word32));
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}
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}
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/**
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* Generic C implementation of Adler32
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* Peak performance:
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* VC++: 52 MB/s on AMD K7 600 MHz
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* gcc: 44 MB/s
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* Borland 5: 48 MB/s
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* (all with speed optimizations on)
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*/
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void mhash_adler32(mutils_word32 * adler, __const void *given_buf, mutils_word32 len)
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{
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mutils_word32 s1 = (*adler) & 0x0000FFFF;
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mutils_word32 s2 = ((*adler) >> 16) & 0x0000FFFF;
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mutils_word32 n;
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mutils_word8 *p = (mutils_word8 *) given_buf;
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for (n = 0; n < len; n++, p++)
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{
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s1 += *p;
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if (s1 >= 65521) /* using modulo took about 7 times longer on my CPU! */
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{
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s1 -= 65521; /* WARNING: it's meant to be >= 65521, not just > ! */
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}
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s2 += s1;
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if (s2 >= 65521) /* same warning applies here, too */
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{
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s2 -= 65521;
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}
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}
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*adler = (s2 << 16) + s1;
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}
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#endif /* ENABLE_ADLER32 */
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