Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * Normal 64-bit CRC calculation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * This is a basic crc64 implementation following ECMA-182 specification,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  * which can be found from,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  * https://www.ecma-international.org/publications/standards/Ecma-182.htm
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  * Dr. Ross N. Williams has a great document to introduce the idea of CRC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)  * algorithm, here the CRC64 code is also inspired by the table-driven
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)  * algorithm and detail example from this paper. This paper can be found
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)  * from,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)  * http://www.ross.net/crc/download/crc_v3.txt
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)  * crc64table[256] is the lookup table of a table-driven 64-bit CRC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)  * calculation, which is generated by gen_crc64table.c in kernel build
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)  * time. The polynomial of crc64 arithmetic is from ECMA-182 specification
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)  * as well, which is defined as,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)  * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)  * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)  * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)  * x^7 + x^4 + x + 1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)  * Copyright 2018 SUSE Linux.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)  *   Author: Coly Li <colyli@suse.de>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) #include <linux/types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) #include <linux/crc64.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) #include "crc64table.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) MODULE_DESCRIPTION("CRC64 calculations");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) MODULE_LICENSE("GPL v2");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)  * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39)  * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	or the previous crc64 value if computing incrementally.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41)  * @p: pointer to buffer over which CRC64 is run
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42)  * @len: length of buffer @p
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) u64 __pure crc64_be(u64 crc, const void *p, size_t len)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	size_t i, t;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	const unsigned char *_p = p;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 	for (i = 0; i < len; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 		t = ((crc >> 56) ^ (*_p++)) & 0xFF;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 		crc = crc64table[t] ^ (crc << 8);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	return crc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) EXPORT_SYMBOL_GPL(crc64_be);