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// SPDX-License-Identifier: 0BSD
///////////////////////////////////////////////////////////////////////////////
//
/// \file crc64_small.c
/// \brief CRC64 calculation (size-optimized)
//
// Author: Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////
#include "check.h"
static uint64_t crc64_table[256];
#ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
__attribute__((__constructor__))
#endif
static void
crc64_init(void)
{
static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
for (size_t b = 0; b < 256; ++b) {
uint64_t r = b;
for (size_t i = 0; i < 8; ++i) {
if (r & 1)
r = (r >> 1) ^ poly64;
else
r >>= 1;
}
crc64_table[b] = r;
}
return;
}
extern LZMA_API(uint64_t)
lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
{
#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
mythread_once(crc64_init);
#endif
crc = ~crc;
while (size != 0) {
crc = crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
--size;
}
return ~crc;
}
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