mirror of
https://github.com/dolphin-emu/dolphin
synced 2024-11-21 12:52:55 -05:00
73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
///////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
/// \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)
|
|
^ *(const uint32_t *)(buf);
|
|
#else
|
|
const uint32_t tmp = crc ^ *(const uint32_t *)(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;
|
|
}
|