0aed504f4a
git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@5917 212acab6-be3b-0410-9dea-997c60f758d6
47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
/*
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* crc32.c
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*
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* This file is a part of NSIS.
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*
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* Copyright (C) 1999-2009 Nullsoft and Contributors
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*
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* Licensed under the zlib/libpng license (the "License");
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* you may not use this file except in compliance with the License.
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*
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* Licence details can be found in the file COPYING.
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*
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* This software is provided 'as-is', without any express or implied
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* warranty.
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*/
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#include "Platform.h"
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#include "crc32.h"
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#include "exehead/config.h"
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#ifdef NSIS_CONFIG_CRC_SUPPORT
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// this is based on the (slow,small) CRC32 implementation from zlib.
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crc32_t NSISCALL CRC32(crc32_t crc, const unsigned char *buf, unsigned int len)
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{
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static crc32_t crc_table[256];
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if (!crc_table[1])
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{
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crc32_t c;
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int n, k;
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for (n = 0; n < 256; n++)
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{
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c = (crc32_t)n;
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for (k = 0; k < 8; k++) c = (c >> 1) ^ (c & 1 ? 0xedb88320L : 0);
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crc_table[n] = c;
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}
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}
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crc = crc ^ 0xffffffffL;
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while (len-- > 0) {
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crc = crc_table[(crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
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}
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return crc ^ 0xffffffffL;
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}
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#endif
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