1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * Normal 64-bit CRC calculation. 3 * Normal 64-bit CRC calculation.
4 * 4 *
5 * This is a basic crc64 implementation follow 5 * This is a basic crc64 implementation following ECMA-182 specification,
6 * which can be found from, 6 * which can be found from,
7 * https://www.ecma-international.org/publicat 7 * https://www.ecma-international.org/publications/standards/Ecma-182.htm
8 * 8 *
9 * Dr. Ross N. Williams has a great document t 9 * Dr. Ross N. Williams has a great document to introduce the idea of CRC
10 * algorithm, here the CRC64 code is also insp 10 * algorithm, here the CRC64 code is also inspired by the table-driven
11 * algorithm and detail example from this pape 11 * algorithm and detail example from this paper. This paper can be found
12 * from, 12 * from,
13 * http://www.ross.net/crc/download/crc_v3.txt 13 * http://www.ross.net/crc/download/crc_v3.txt
14 * 14 *
15 * crc64table[256] is the lookup table of a ta 15 * crc64table[256] is the lookup table of a table-driven 64-bit CRC
16 * calculation, which is generated by gen_crc6 16 * calculation, which is generated by gen_crc64table.c in kernel build
17 * time. The polynomial of crc64 arithmetic is 17 * time. The polynomial of crc64 arithmetic is from ECMA-182 specification
18 * as well, which is defined as, 18 * as well, which is defined as,
19 * 19 *
20 * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x 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 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 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 23 * x^7 + x^4 + x + 1
24 * 24 *
25 * crc64rocksoft[256] table is from the Rockso <<
26 * defined as, <<
27 * <<
28 * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x <<
29 * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x <<
30 * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x <<
31 * <<
32 * Copyright 2018 SUSE Linux. 25 * Copyright 2018 SUSE Linux.
33 * Author: Coly Li <colyli@suse.de> 26 * Author: Coly Li <colyli@suse.de>
34 */ 27 */
35 28
36 #include <linux/module.h> 29 #include <linux/module.h>
37 #include <linux/types.h> 30 #include <linux/types.h>
38 #include <linux/crc64.h> 31 #include <linux/crc64.h>
39 #include "crc64table.h" 32 #include "crc64table.h"
40 33
41 MODULE_DESCRIPTION("CRC64 calculations"); 34 MODULE_DESCRIPTION("CRC64 calculations");
42 MODULE_LICENSE("GPL v2"); 35 MODULE_LICENSE("GPL v2");
43 36
44 /** 37 /**
45 * crc64_be - Calculate bitwise big-endian ECM 38 * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64
46 * @crc: seed value for computation. 0 or (u64 39 * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation,
47 * or the previous crc64 value if comput 40 * or the previous crc64 value if computing incrementally.
48 * @p: pointer to buffer over which CRC64 is r 41 * @p: pointer to buffer over which CRC64 is run
49 * @len: length of buffer @p 42 * @len: length of buffer @p
50 */ 43 */
51 u64 __pure crc64_be(u64 crc, const void *p, si 44 u64 __pure crc64_be(u64 crc, const void *p, size_t len)
52 { 45 {
53 size_t i, t; 46 size_t i, t;
54 47
55 const unsigned char *_p = p; 48 const unsigned char *_p = p;
56 49
57 for (i = 0; i < len; i++) { 50 for (i = 0; i < len; i++) {
58 t = ((crc >> 56) ^ (*_p++)) & 51 t = ((crc >> 56) ^ (*_p++)) & 0xFF;
59 crc = crc64table[t] ^ (crc << 52 crc = crc64table[t] ^ (crc << 8);
60 } 53 }
61 54
62 return crc; 55 return crc;
63 } 56 }
64 EXPORT_SYMBOL_GPL(crc64_be); 57 EXPORT_SYMBOL_GPL(crc64_be);
65 <<
66 /** <<
67 * crc64_rocksoft_generic - Calculate bitwise <<
68 * @crc: seed value for computation. 0 for a n <<
69 * previous crc64 value if computing inc <<
70 * @p: pointer to buffer over which CRC64 is r <<
71 * @len: length of buffer @p <<
72 */ <<
73 u64 __pure crc64_rocksoft_generic(u64 crc, con <<
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) ^ crc64rockso <<
82 <<
83 return ~crc; <<
84 } <<
85 EXPORT_SYMBOL_GPL(crc64_rocksoft_generic); <<
86 58
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