On 2018/7/17 1:57 AM, Randy Dunlap wrote: > On 07/16/2018 09:55 AM, Coly Li wrote: >> >> diff --git a/lib/crc64.c b/lib/crc64.c >> new file mode 100644 >> index 000000000000..03f078303bd3 >> --- /dev/null >> +++ b/lib/crc64.c >> @@ -0,0 +1,71 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Normal 64bit CRC calculation. >> + * >> + * This is a basic crc64 implementation following ECMA-182 specification, >> + * which can be found from, >> + * http://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_le[256] is the lookup table of a table-driver 64bit 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 >> + * >> + * Copyright 2018 SUSE Linux. >> + * Author: Coly Li <colyli@xxxxxxx> >> + * >> + */ >> + >> +#include <linux/module.h> >> +#include <uapi/linux/types.h> >> +#include "crc64table.h" >> + >> +MODULE_DESCRIPTION("CRC64 calculations"); >> +MODULE_LICENSE("GPL"); >> + >> +__le64 crc64_le_update(__le64 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) ^ (__le64)(*p++)) & 0xFF; >> + crc = crc64table_le[t] ^ (crc << 8); >> + } >> + >> + return crc; >> +} >> +EXPORT_SYMBOL_GPL(crc64_le_update); >> + >> +__le64 crc64_le(const void *p, size_t len) >> +{ >> + __le64 crc = 0x0000000000000000ULL; > Hi Randy, > Hi, > What's wrong with just using 0ULL ? In v2 series it will be 0x0ULL :-) Thanks. Coly Li
