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 #include <linux/swab.h> 20 21 #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL 22 23 static uint64_t crc64_table[256] = {0}; 24 25 static void generate_crc64_table(void) 26 { 27 uint64_t i, j, c, crc; 28 29 for (i = 0; i < 256; i++) { 30 crc = 0; 31 c = i << 56; 32 33 for (j = 0; j < 8; j++) { 34 if ((crc ^ c) & 0x8000000000000000ULL) 35 crc = (crc << 1) ^ CRC64_ECMA182_POLY; 36 else 37 crc <<= 1; 38 c <<= 1; 39 } 40 41 crc64_table[i] = crc; 42 } 43 } 44 45 static void print_crc64_table(void) 46 { 47 int i; 48 49 printf("/* this file is generated - do not edit */\n\n"); 50 printf("#include <linux/types.h>\n"); 51 printf("#include <linux/cache.h>\n\n"); 52 printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); 53 for (i = 0; i < 256; i++) { 54 printf("\t0x%016" PRIx64 "ULL", crc64_table[i]); 55 if (i & 0x1) 56 printf(",\n"); 57 else 58 printf(", "); 59 } 60 printf("};\n"); 61 } 62 63 int main(int argc, char *argv[]) 64 { 65 generate_crc64_table(); 66 print_crc64_table(); 67 return 0; 68 } 69