86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
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/*-----------------------------------------------------------*/
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/* Block Sorting, Lossless Data Compression Library. */
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/* Adler-32 checksum functions */
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/*-----------------------------------------------------------*/
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/*--
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This file is a part of bsc and/or libbsc, a program and a library for
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lossless, block-sorting data compression.
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Copyright (c) 2009-2012 Ilya Grebnov <ilya.grebnov@gmail.com>
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See file AUTHORS for a full list of contributors.
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The bsc and libbsc is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The bsc and libbsc is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the bsc and libbsc. If not, see http://www.gnu.org/licenses/.
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Please see the files COPYING and COPYING.LIB for full copyright information.
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See also the bsc and libbsc web site:
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http://libbsc.com/ for more information.
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--*/
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#include <stdlib.h>
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#include <memory.h>
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#include <string.h>
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#include "adler32.h"
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#include "../platform/platform.h"
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#include "../libbsc.h"
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#define BASE 65521UL
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#define NMAX 5552
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#define DO1(buf, i) { sum1 += (buf)[i]; sum2 += sum1; }
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#define DO2(buf, i) DO1(buf, i); DO1(buf, i + 1);
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#define DO4(buf, i) DO2(buf, i); DO2(buf, i + 2);
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#define DO8(buf, i) DO4(buf, i); DO4(buf, i + 4);
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#define DO16(buf) DO8(buf, 0); DO8(buf, 8);
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#define MOD(a) a %= BASE
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unsigned int bsc_adler32(const unsigned char * T, int n, int features)
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{
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unsigned int sum1 = 1;
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unsigned int sum2 = 0;
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while (n >= NMAX)
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{
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for (int i = 0; i < NMAX / 16; ++i)
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{
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DO16(T); T += 16;
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}
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MOD(sum1); MOD(sum2); n -= NMAX;
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}
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while (n >= 16)
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{
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DO16(T); T += 16; n -= 16;
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}
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while (n > 0)
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{
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DO1(T, 0); T += 1; n -= 1;
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}
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MOD(sum1); MOD(sum2);
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return sum1 | (sum2 << 16);
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}
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/*-----------------------------------------------------------*/
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/* End adler32.cpp */
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/*-----------------------------------------------------------*/
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