1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       crc64.c
4/// \brief      CRC64 calculation
5///
6/// Calculate the CRC64 using the slice-by-four algorithm. This is the same
7/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables
8/// instead of eight to avoid increasing CPU cache usage.
9//
10//  Author:     Lasse Collin
11//
12//  This file has been put into the public domain.
13//  You can do whatever you want with this file.
14//
15///////////////////////////////////////////////////////////////////////////////
16
17#include "check.h"
18#include "crc_macros.h"
19
20
21#ifdef WORDS_BIGENDIAN
22#	define A1(x) ((x) >> 56)
23#else
24#	define A1 A
25#endif
26
27
28// See the comments in crc32_fast.c. They aren't duplicated here.
29extern LZMA_API(uint64_t)
30lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
31{
32	crc = ~crc;
33
34#ifdef WORDS_BIGENDIAN
35	crc = bswap64(crc);
36#endif
37
38	if (size > 4) {
39		while ((uintptr_t)(buf) & 3) {
40			crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
41			--size;
42		}
43
44		const uint8_t *const limit = buf + (size & ~(size_t)(3));
45		size &= (size_t)(3);
46
47		while (buf < limit) {
48#ifdef WORDS_BIGENDIAN
49			const uint32_t tmp = (crc >> 32)
50					^ *(const uint32_t *)(buf);
51#else
52			const uint32_t tmp = crc ^ *(const uint32_t *)(buf);
53#endif
54			buf += 4;
55
56			crc = lzma_crc64_table[3][A(tmp)]
57			    ^ lzma_crc64_table[2][B(tmp)]
58			    ^ S32(crc)
59			    ^ lzma_crc64_table[1][C(tmp)]
60			    ^ lzma_crc64_table[0][D(tmp)];
61		}
62	}
63
64	while (size-- != 0)
65		crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
66
67#ifdef WORDS_BIGENDIAN
68	crc = bswap64(crc);
69#endif
70
71	return ~crc;
72}
73