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/module.h>
37 #include <linux/types.h>
38 #include <linux/crc64.h>
39 #include "crc64table.h"
40
41 MODULE_DESCRIPTION("CRC64 calculations");
42 MODULE_LICENSE("GPL v2");
43
crc64_be_generic(u64 crc,const u8 * p,size_t len)44 u64 crc64_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 EXPORT_SYMBOL_GPL(crc64_be_generic);
51
crc64_nvme_generic(u64 crc,const u8 * p,size_t len)52 u64 crc64_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 EXPORT_SYMBOL_GPL(crc64_nvme_generic);
59