Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * Generate lookup table for the table-driven CRC64 calculation. |
| 4 | * |
| 5 | * gen_crc64table is executed in kernel build time and generates |
| 6 | * lib/crc64table.h. This header is included by lib/crc64.c for |
| 7 | * the table-driven CRC64 calculation. |
| 8 | * |
| 9 | * See lib/crc64.c for more information about which specification |
| 10 | * and polynomial arithmetic that gen_crc64table.c follows to |
| 11 | * generate the lookup table. |
| 12 | * |
| 13 | * Copyright 2018 SUSE Linux. |
| 14 | * Author: Coly Li <colyli@suse.de> |
| 15 | */ |
| 16 | #include <inttypes.h> |
| 17 | #include <stdio.h> |
| 18 | |
Coly Li | feba04f | 2018-08-21 21:57:11 -0700 | [diff] [blame] | 19 | #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL |
| 20 | |
| 21 | static uint64_t crc64_table[256] = {0}; |
| 22 | |
| 23 | static void generate_crc64_table(void) |
| 24 | { |
| 25 | uint64_t i, j, c, crc; |
| 26 | |
| 27 | for (i = 0; i < 256; i++) { |
| 28 | crc = 0; |
| 29 | c = i << 56; |
| 30 | |
| 31 | for (j = 0; j < 8; j++) { |
| 32 | if ((crc ^ c) & 0x8000000000000000ULL) |
| 33 | crc = (crc << 1) ^ CRC64_ECMA182_POLY; |
| 34 | else |
| 35 | crc <<= 1; |
| 36 | c <<= 1; |
| 37 | } |
| 38 | |
| 39 | crc64_table[i] = crc; |
| 40 | } |
| 41 | } |
| 42 | |
| 43 | static void print_crc64_table(void) |
| 44 | { |
| 45 | int i; |
| 46 | |
| 47 | printf("/* this file is generated - do not edit */\n\n"); |
| 48 | printf("#include <linux/types.h>\n"); |
| 49 | printf("#include <linux/cache.h>\n\n"); |
| 50 | printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); |
| 51 | for (i = 0; i < 256; i++) { |
| 52 | printf("\t0x%016" PRIx64 "ULL", crc64_table[i]); |
| 53 | if (i & 0x1) |
| 54 | printf(",\n"); |
| 55 | else |
| 56 | printf(", "); |
| 57 | } |
| 58 | printf("};\n"); |
| 59 | } |
| 60 | |
| 61 | int main(int argc, char *argv[]) |
| 62 | { |
| 63 | generate_crc64_table(); |
| 64 | print_crc64_table(); |
| 65 | return 0; |
| 66 | } |