crc64-main.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Normal 64-bit CRC calculation.
 4 *
 5 * This is a basic crc64 implementation following ECMA-182 specification,
 6 * which can be found from,
 7 * https://www.ecma-international.org/publications/standards/Ecma-182.htm
 8 *
 9 * Dr. Ross N. Williams has a great document to introduce the idea of CRC
10 * algorithm, here the CRC64 code is also inspired by the table-driven
11 * algorithm and detail example from this paper. This paper can be found
12 * from,
13 * http://www.ross.net/crc/download/crc_v3.txt
14 *
15 * crc64table[256] is the lookup table of a table-driven 64-bit CRC
16 * calculation, which is generated by gen_crc64table.c in kernel build
17 * time. The polynomial of crc64 arithmetic is from ECMA-182 specification
18 * as well, which is defined as,
19 *
20 * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
21 * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
22 * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
23 * x^7 + x^4 + x + 1
24 *
25 * crc64nvmetable[256] uses the CRC64 polynomial from the NVME NVM Command Set
26 * Specification and uses least-significant-bit first bit order:
27 *
28 * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 +
29 * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 +
30 * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1
31 *
32 * Copyright 2018 SUSE Linux.
33 *   Author: Coly Li <colyli@suse.de>
34 */
35
36#include <linux/crc64.h>
37#include <linux/export.h>
38#include <linux/module.h>
39#include <linux/types.h>
40
41#include "crc64table.h"
42
43static inline u64 __maybe_unused
44crc64_be_generic(u64 crc, const u8 *p, size_t len)
45{
46	while (len--)
47		crc = (crc << 8) ^ crc64table[(crc >> 56) ^ *p++];
48	return crc;
49}
50
51static inline u64 __maybe_unused
52crc64_nvme_generic(u64 crc, const u8 *p, size_t len)
53{
54	while (len--)
55		crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *p++];
56	return crc;
57}
58
59#ifdef CONFIG_CRC64_ARCH
60#include "crc64.h" /* $(SRCARCH)/crc64.h */
61#else
62#define crc64_be_arch crc64_be_generic
63#define crc64_nvme_arch crc64_nvme_generic
64#endif
65
66u64 crc64_be(u64 crc, const void *p, size_t len)
67{
68	return crc64_be_arch(crc, p, len);
69}
70EXPORT_SYMBOL_GPL(crc64_be);
71
72u64 crc64_nvme(u64 crc, const void *p, size_t len)
73{
74	return ~crc64_nvme_arch(~crc, p, len);
75}
76EXPORT_SYMBOL_GPL(crc64_nvme);
77
78#ifdef crc64_mod_init_arch
79static int __init crc64_mod_init(void)
80{
81	crc64_mod_init_arch();
82	return 0;
83}
84subsys_initcall(crc64_mod_init);
85
86static void __exit crc64_mod_exit(void)
87{
88}
89module_exit(crc64_mod_exit);
90#endif
91
92MODULE_DESCRIPTION("CRC64 library functions");
93MODULE_LICENSE("GPL");