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///////////////////////////////////////////////////////////////////////////////
//
/// \file crc64.c
/// \brief CRC64 calculation
//
// This code has been put into the public domain.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
///////////////////////////////////////////////////////////////////////////////
#include "check.h"
#include "crc_macros.h"
#ifdef WORDS_BIGENDIAN
# define A1(x) ((x) >> 56)
#else
# define A1 A
#endif
// See comments in crc32.c.
extern LZMA_API uint64_t
lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
{
crc = ~crc;
#ifdef WORDS_BIGENDIAN
crc = bswap_64(crc);
#endif
if (size > 4) {
while ((uintptr_t)(buf) & 3) {
crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
--size;
}
const uint8_t *const limit = buf + (size & ~(size_t)(3));
size &= (size_t)(3);
// Calculate the CRC64 using the slice-by-four algorithm.
//
// In contrast to CRC32 code, this one seems to be fastest
// with -O3 -fomit-frame-pointer.
while (buf < limit) {
#ifdef WORDS_BIGENDIAN
const uint32_t tmp = (crc >> 32) ^ *(uint32_t *)(buf);
#else
const uint32_t tmp = crc ^ *(uint32_t *)(buf);
#endif
buf += 4;
// It is critical for performance, that
// the crc variable is XORed between the
// two table-lookup pairs.
crc = lzma_crc64_table[3][A(tmp)]
^ lzma_crc64_table[2][B(tmp)]
^ S32(crc)
^ lzma_crc64_table[1][C(tmp)]
^ lzma_crc64_table[0][D(tmp)];
}
}
while (size-- != 0)
crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
#ifdef WORDS_BIGENDIAN
crc = bswap_64(crc);
#endif
return ~crc;
}
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