On Thu, 26 Jul 2018 13:33:51 +0800 Coly Li <colyli@xxxxxxx> wrote: > This patch adds the re-write crc64 calculation routines for Linux kernel. > The CRC64 polynomial arithmetic follows ECMA-182 specification, inspired > by CRC paper of Dr. Ross N. Williams > (see http://www.ross.net/crc/download/crc_v3.txt) and other public domain > implementations. > > All the changes work in this way, > - When Linux kernel is built, host program lib/gen_crc64table.c will be > compiled to lib/gen_crc64table and executed. > - The output of gen_crc64table execution is an array called as lookup > table (a.k.a POLY 0x42f0e1eba9ea369) which contain 256 64-bit long > numbers, this talbe is dumped into header file lib/crc64table.h. > - Then the header file is included by lib/crc64.c for normal 64bit crc > calculation. > - Function declaration of the crc64 calculation routines is placed in > include/linux/crc64.h > > Currently bcache is the only user of crc64_be(), another potential user > is bcachefs which is on the way to be in mainline kernel. Therefore it > makes sense to move crc64 calculation into lib/crc64.c as public code. delta from v4: --- a/include/linux/crc64.h~lib-add-crc64-calculation-routines-v5 +++ a/include/linux/crc64.h @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0 */ /* - * See lib/crc64.c for the related specification and polynomical arithmetic. + * See lib/crc64.c for the related specification and polynomial arithmetic. */ #ifndef _LINUX_CRC64_H #define _LINUX_CRC64_H --- a/lib/crc64.c~lib-add-crc64-calculation-routines-v5 +++ a/lib/crc64.c @@ -12,7 +12,7 @@ * from, * http://www.ross.net/crc/download/crc_v3.txt * - * crc64table[256] is the lookup table of a table-driver 64-bit CRC + * 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, @@ -35,8 +35,8 @@ MODULE_LICENSE("GPL v2"); /** * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64 - * @crc: seed value for computation. 0 for a new CRC computing, or the - * previous crc64 value if computing incrementally. + * @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 */ --- a/lib/gen_crc64table.c~lib-add-crc64-calculation-routines-v5 +++ a/lib/gen_crc64table.c @@ -1,13 +1,13 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Generate lookup table for the talbe-driven CRC64 calculation. + * Generate lookup table for the table-driven CRC64 calculation. * * gen_crc64table is executed in kernel build time and generates * lib/crc64table.h. This header is included by lib/crc64.c for - * the table-driver CRC64 calculation. + * the table-driven CRC64 calculation. * * See lib/crc64.c for more information about which specification - * and polynomical arithmetic that gen_crc64table.c follows to + * and polynomial arithmetic that gen_crc64table.c follows to * generate the lookup table. * * Copyright 2018 SUSE Linux. @@ -20,7 +20,7 @@ #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL -static int64_t crc64_table[256] = {0}; +static uint64_t crc64_table[256] = {0}; static void generate_crc64_table(void) {
