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/*
* crc32.c
*
* This file is a part of NSIS.
*
* Copyright (C) 1999-2025 Nullsoft and Contributors
*
* Licensed under the zlib/libpng license (the "License");
* you may not use this file except in compliance with the License.
*
* Licence details can be found in the file COPYING.
*
* This software is provided 'as-is', without any express or implied
* warranty.
*
* Unicode support by Jim Park -- 08/24/2007
*/
#include "Platform.h"
#include "crc32.h"
#include "exehead/config.h"
#ifdef NSIS_CONFIG_CRC_SUPPORT
// this is based on the (slow,small) CRC32 implementation from zlib.
crc32_t NSISCALL CRC32(crc32_t crc, const unsigned char *buf, size_t len)
{
static crc32_t crc_table[256];
if (!crc_table[1])
{
crc32_t c;
int n, k;
for (n = 0; n < 256; n++)
{
c = (crc32_t)n;
for (k = 0; k < 8; k++) c = (c >> 1) ^ (c & 1 ? 0xedb88320L : 0);
crc_table[n] = c;
}
}
crc = crc ^ 0xffffffffL;
while (len-- > 0) {
crc = crc_table[(crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
}
return crc ^ 0xffffffffL;
}
#endif
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