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 19 #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL 20 #define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL 21 22 static uint64_t crc64_table[256] = {0}; 23 static uint64_t crc64_rocksoft_table[256] = {0}; 24 25 static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly) 26 { 27 uint64_t i, j, c, crc; 28 29 for (i = 0; i < 256; i++) { 30 crc = 0ULL; 31 c = i; 32 33 for (j = 0; j < 8; j++) { 34 if ((crc ^ (c >> j)) & 1) 35 crc = (crc >> 1) ^ poly; 36 else 37 crc >>= 1; 38 } 39 table[i] = crc; 40 } 41 } 42 43 static void generate_crc64_table(uint64_t table[256], uint64_t poly) 44 { 45 uint64_t i, j, c, crc; 46 47 for (i = 0; i < 256; i++) { 48 crc = 0; 49 c = i << 56; 50 51 for (j = 0; j < 8; j++) { 52 if ((crc ^ c) & 0x8000000000000000ULL) 53 crc = (crc << 1) ^ poly; 54 else 55 crc <<= 1; 56 c <<= 1; 57 } 58 59 table[i] = crc; 60 } 61 } 62 63 static void output_table(uint64_t table[256]) 64 { 65 int i; 66 67 for (i = 0; i < 256; i++) { 68 printf("\t0x%016" PRIx64 "ULL", table[i]); 69 if (i & 0x1) 70 printf(",\n"); 71 else 72 printf(", "); 73 } 74 printf("};\n"); 75 } 76 77 static void print_crc64_tables(void) 78 { 79 printf("/* this file is generated - do not edit */\n\n"); 80 printf("#include <linux/types.h>\n"); 81 printf("#include <linux/cache.h>\n\n"); 82 printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); 83 output_table(crc64_table); 84 85 printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n"); 86 output_table(crc64_rocksoft_table); 87 } 88 89 int main(int argc, char *argv[]) 90 { 91 generate_crc64_table(crc64_table, CRC64_ECMA182_POLY); 92 generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY); 93 print_crc64_tables(); 94 return 0; 95 } 96