VisionFive2 Linux kernel

feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  1) // SPDX-License-Identifier: GPL-2.0
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  2) /*
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  3)  * Normal 64-bit CRC calculation.
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  4)  *
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  5)  * This is a basic crc64 implementation following ECMA-182 specification,
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  6)  * which can be found from,
d89775fc929c5 (Alexander A. Klimov   2020-08-11 18:34:50 -0700  7)  * https://www.ecma-international.org/publications/standards/Ecma-182.htm
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  8)  *
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700  9)  * Dr. Ross N. Williams has a great document to introduce the idea of CRC
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 10)  * algorithm, here the CRC64 code is also inspired by the table-driven
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 11)  * algorithm and detail example from this paper. This paper can be found
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 12)  * from,
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 13)  * http://www.ross.net/crc/download/crc_v3.txt
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 14)  *
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 15)  * crc64table[256] is the lookup table of a table-driven 64-bit CRC
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 16)  * calculation, which is generated by gen_crc64table.c in kernel build
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 17)  * time. The polynomial of crc64 arithmetic is from ECMA-182 specification
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 18)  * as well, which is defined as,
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 19)  *
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 20)  * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 21)  * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 22)  * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 23)  * x^7 + x^4 + x + 1
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 24)  *
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 25)  * Copyright 2018 SUSE Linux.
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 26)  *   Author: Coly Li <colyli@suse.de>
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 27)  */
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 28) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 29) #include <linux/module.h>
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 30) #include <linux/types.h>
0e0c12316d8a6 (Ben Dooks (Codethink) 2020-01-24 01:01:35 +0800 31) #include <linux/crc64.h>
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 32) #include "crc64table.h"
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 33) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 34) MODULE_DESCRIPTION("CRC64 calculations");
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 35) MODULE_LICENSE("GPL v2");
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 36) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 37) /**
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 38)  * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 39)  * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation,
415f0c835ba79 (YueHaibing            2021-06-04 20:01:39 -0700 40)  *       or the previous crc64 value if computing incrementally.
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 41)  * @p: pointer to buffer over which CRC64 is run
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 42)  * @len: length of buffer @p
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 43)  */
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 44) u64 __pure crc64_be(u64 crc, const void *p, size_t len)
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 45) {
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 46) 	size_t i, t;
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 47) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 48) 	const unsigned char *_p = p;
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 49) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 50) 	for (i = 0; i < len; i++) {
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 51) 		t = ((crc >> 56) ^ (*_p++)) & 0xFF;
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 52) 		crc = crc64table[t] ^ (crc << 8);
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 53) 	}
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 54) 
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 55) 	return crc;
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 56) }
feba04fd2cf8f (Coly Li               2018-08-21 21:57:11 -0700 57) EXPORT_SYMBOL_GPL(crc64_be);