86 lines · c
1// SPDX-License-Identifier: GPL-2.02/*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.htm8 *9 * Dr. Ross N. Williams has a great document to introduce the idea of CRC10 * algorithm, here the CRC64 code is also inspired by the table-driven11 * algorithm and detail example from this paper. This paper can be found12 * from,13 * http://www.ross.net/crc/download/crc_v3.txt14 *15 * crc64table[256] is the lookup table of a table-driven 64-bit CRC16 * calculation, which is generated by gen_crc64table.c in kernel build17 * time. The polynomial of crc64 arithmetic is from ECMA-182 specification18 * 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 + 124 *25 * crc64rocksoft[256] table is from the Rocksoft specification polynomial26 * 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 + 131 *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 41MODULE_DESCRIPTION("CRC64 calculations");42MODULE_LICENSE("GPL v2");43 44/**45 * crc64_be - Calculate bitwise big-endian ECMA-182 CRC6446 * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation,47 * or the previous crc64 value if computing incrementally.48 * @p: pointer to buffer over which CRC64 is run49 * @len: length of buffer @p50 */51u64 __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}64EXPORT_SYMBOL_GPL(crc64_be);65 66/**67 * crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC6468 * @crc: seed value for computation. 0 for a new CRC calculation, or the69 * previous crc64 value if computing incrementally.70 * @p: pointer to buffer over which CRC64 is run71 * @len: length of buffer @p72 */73u64 __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}85EXPORT_SYMBOL_GPL(crc64_rocksoft_generic);86