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 <[email protected]> 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 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 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