// SPDX-License-Identifier: GPL-2.0/* * Normal 64-bit CRC calculation. * * This is a basic crc64 implementation following ECMA-182 specification, * which can be found from, * https://www.ecma-international.org/publications/standards/Ecma-182.htm * * Dr. Ross N. Williams has a great document to introduce the idea of CRC * algorithm, here the CRC64 code is also inspired by the table-driven * algorithm and detail example from this paper. This paper can be found * from, * http://www.ross.net/crc/download/crc_v3.txt * * crc64table[256] is the lookup table of a table-driven 64-bit CRC * calculation, which is generated by gen_crc64table.c in kernel build * time. The polynomial of crc64 arithmetic is from ECMA-182 specification * as well, which is defined as, * * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 + * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 + * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 + * x^7 + x^4 + x + 1 * * crc64rocksoft[256] table is from the Rocksoft specification polynomial * defined as, * * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 + * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 + * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1 * * Copyright 2018 SUSE Linux. *   Author: Coly Li <colyli@suse.de> */ #include <linux/module.h>#include <linux/types.h>#include <linux/crc64.h>#include "crc64table.h" MODULE_DESCRIPTION("CRC64 calculations");MODULE_LICENSE("GPL v2"); /** * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64 * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation, *       or the previous crc64 value if computing incrementally. * @p: pointer to buffer over which CRC64 is run * @len: length of buffer @p */u64 __pure crc64_be(u64 crc, const void *p, size_t len){	size_t i, t; 	const unsigned char *_p = p; 	for (i = 0; i < len; i++) {		t = ((crc >> 56) ^ (*_p++)) & 0xFF;		crc = crc64table[t] ^ (crc << 8);	} 	return crc;}EXPORT_SYMBOL_GPL(crc64_be); /** * crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC64 * @crc: seed value for computation. 0 for a new CRC calculation, or the * 	 previous crc64 value if computing incrementally. * @p: pointer to buffer over which CRC64 is run * @len: length of buffer @p */u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len){	const unsigned char *_p = p;	size_t i; 	crc = ~crc; 	for (i = 0; i < len; i++)		crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++]; 	return ~crc;}EXPORT_SYMBOL_GPL(crc64_rocksoft_generic);