1// SPDX-License-Identifier: 0BSD
2
3///////////////////////////////////////////////////////////////////////////////
4//
5/// \file       crc64.c
6/// \brief      CRC64 calculation
7//
8//  Authors:    Lasse Collin
9//              Ilya Kurdyukov
10//
11///////////////////////////////////////////////////////////////////////////////
12
13#include "check.h"
14#include "crc_common.h"
15
16#if defined(CRC_X86_CLMUL)
17#	define BUILDING_CRC64_CLMUL
18#	include "crc_x86_clmul.h"
19#endif
20
21
22#ifdef CRC64_GENERIC
23
24/////////////////////////////////
25// Generic slice-by-four CRC64 //
26/////////////////////////////////
27
28#ifdef WORDS_BIGENDIAN
29#	define A1(x) ((x) >> 56)
30#else
31#	define A1 A
32#endif
33
34
35// See the comments in crc32_fast.c. They aren't duplicated here.
36static uint64_t
37crc64_generic(const uint8_t *buf, size_t size, uint64_t crc)
38{
39	crc = ~crc;
40
41#ifdef WORDS_BIGENDIAN
42	crc = byteswap64(crc);
43#endif
44
45	if (size > 4) {
46		while ((uintptr_t)(buf) & 3) {
47			crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
48			--size;
49		}
50
51		const uint8_t *const limit = buf + (size & ~(size_t)(3));
52		size &= (size_t)(3);
53
54		while (buf < limit) {
55#ifdef WORDS_BIGENDIAN
56			const uint32_t tmp = (uint32_t)(crc >> 32)
57					^ aligned_read32ne(buf);
58#else
59			const uint32_t tmp = (uint32_t)crc
60					^ aligned_read32ne(buf);
61#endif
62			buf += 4;
63
64			crc = lzma_crc64_table[3][A(tmp)]
65			    ^ lzma_crc64_table[2][B(tmp)]
66			    ^ S32(crc)
67			    ^ lzma_crc64_table[1][C(tmp)]
68			    ^ lzma_crc64_table[0][D(tmp)];
69		}
70	}
71
72	while (size-- != 0)
73		crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
74
75#ifdef WORDS_BIGENDIAN
76	crc = byteswap64(crc);
77#endif
78
79	return ~crc;
80}
81#endif
82
83
84#if defined(CRC64_GENERIC) && defined(CRC64_ARCH_OPTIMIZED)
85
86//////////////////////////
87// Function dispatching //
88//////////////////////////
89
90// If both the generic and arch-optimized implementations are usable, then
91// the function that is used is selected at runtime. See crc32_fast.c.
92
93typedef uint64_t (*crc64_func_type)(
94		const uint8_t *buf, size_t size, uint64_t crc);
95
96static crc64_func_type
97crc64_resolve(void)
98{
99	return is_arch_extension_supported()
100			? &crc64_arch_optimized : &crc64_generic;
101}
102
103#ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
104#	define CRC64_SET_FUNC_ATTR __attribute__((__constructor__))
105static crc64_func_type crc64_func;
106#else
107#	define CRC64_SET_FUNC_ATTR
108static uint64_t crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc);
109static crc64_func_type crc64_func = &crc64_dispatch;
110#endif
111
112
113CRC64_SET_FUNC_ATTR
114static void
115crc64_set_func(void)
116{
117	crc64_func = crc64_resolve();
118	return;
119}
120
121
122#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
123static uint64_t
124crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc)
125{
126	crc64_set_func();
127	return crc64_func(buf, size, crc);
128}
129#endif
130#endif
131
132
133extern LZMA_API(uint64_t)
134lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
135{
136#if defined(CRC64_GENERIC) && defined(CRC64_ARCH_OPTIMIZED)
137
138#ifdef CRC_USE_GENERIC_FOR_SMALL_INPUTS
139	if (size <= 16)
140		return crc64_generic(buf, size, crc);
141#endif
142	return crc64_func(buf, size, crc);
143
144#elif defined(CRC64_ARCH_OPTIMIZED)
145	// If arch-optimized version is used unconditionally without runtime
146	// CPU detection then omitting the generic version and its 8 KiB
147	// lookup table makes the library smaller.
148	//
149	// FIXME: Lookup table isn't currently omitted on 32-bit x86,
150	// see crc64_table.c.
151	return crc64_arch_optimized(buf, size, crc);
152
153#else
154	return crc64_generic(buf, size, crc);
155#endif
156}
157