Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 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, |
Alexander A. Klimov | d89775f | 2020-08-11 18:34:50 -0700 | [diff] [blame] | 7 | * https://www.ecma-international.org/publications/standards/Ecma-182.htm |
Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 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 | * |
Keith Busch | cbc0a40 | 2022-03-03 12:13:09 -0800 | [diff] [blame] | 25 | * crc64rocksoft[256] table is from the Rocksoft specification polynomial |
| 26 | * defined as, |
| 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 | * |
Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 32 | * Copyright 2018 SUSE Linux. |
| 33 | * Author: Coly Li <colyli@suse.de> |
| 34 | */ |
| 35 | |
| 36 | #include <linux/module.h> |
| 37 | #include <linux/types.h> |
Ben Dooks (Codethink) | 0e0c123 | 2020-01-24 01:01:35 +0800 | [diff] [blame] | 38 | #include <linux/crc64.h> |
Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 39 | #include "crc64table.h" |
| 40 | |
| 41 | MODULE_DESCRIPTION("CRC64 calculations"); |
| 42 | MODULE_LICENSE("GPL v2"); |
| 43 | |
| 44 | /** |
| 45 | * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64 |
| 46 | * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation, |
YueHaibing | 415f0c8 | 2021-06-04 20:01:39 -0700 | [diff] [blame] | 47 | * or the previous crc64 value if computing incrementally. |
Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 48 | * @p: pointer to buffer over which CRC64 is run |
| 49 | * @len: length of buffer @p |
| 50 | */ |
| 51 | u64 __pure crc64_be(u64 crc, const void *p, size_t len) |
| 52 | { |
| 53 | size_t i, t; |
| 54 | |
| 55 | const unsigned char *_p = p; |
| 56 | |
| 57 | for (i = 0; i < len; i++) { |
| 58 | t = ((crc >> 56) ^ (*_p++)) & 0xFF; |
| 59 | crc = crc64table[t] ^ (crc << 8); |
| 60 | } |
| 61 | |
| 62 | return crc; |
| 63 | } |
| 64 | EXPORT_SYMBOL_GPL(crc64_be); |
Keith Busch | cbc0a40 | 2022-03-03 12:13:09 -0800 | [diff] [blame] | 65 | |
| 66 | /** |
| 67 | * crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC64 |
| 68 | * @crc: seed value for computation. 0 for a new CRC calculation, or the |
| 69 | * previous crc64 value if computing incrementally. |
| 70 | * @p: pointer to buffer over which CRC64 is run |
| 71 | * @len: length of buffer @p |
| 72 | */ |
| 73 | u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len) |
| 74 | { |
| 75 | const unsigned char *_p = p; |
| 76 | size_t i; |
| 77 | |
| 78 | crc = ~crc; |
| 79 | |
| 80 | for (i = 0; i < len; i++) |
| 81 | crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++]; |
| 82 | |
| 83 | return ~crc; |
| 84 | } |
| 85 | EXPORT_SYMBOL_GPL(crc64_rocksoft_generic); |