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///////////////////////////////////////////////////////////////////////////////
//
/// \file crc64.c
/// \brief CRC64 calculation
///
/// Calculate the CRC64 using the slice-by-four algorithm. This is the same
/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables
/// instead of eight to avoid increasing CPU cache usage.
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "check.h"
#include "crc_macros.h"
#ifdef WORDS_BIGENDIAN
# define A1(x) ((x) >> 56)
#else
# define A1 A
#endif
// See the comments in crc32_fast.c. They aren't duplicated here.
extern LZMA_API(uint64_t)
lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
{
crc = ~crc;
#ifdef WORDS_BIGENDIAN
crc = bswap64(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);
while (buf < limit) {
#ifdef WORDS_BIGENDIAN
const uint32_t tmp = (crc >> 32)
^ aligned_read32ne(buf);
#else
const uint32_t tmp = crc ^ aligned_read32ne(buf);
#endif
buf += 4;
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 = bswap64(crc);
#endif
return ~crc;
}
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