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1// SPDX-License-Identifier: GPL-2.02/*3 * Generate lookup table for the table-driven CRC64 calculation.4 *5 * gen_crc64table is executed in kernel build time and generates6 * lib/crc64table.h. This header is included by lib/crc64.c for7 * the table-driven CRC64 calculation.8 *9 * See lib/crc64.c for more information about which specification10 * and polynomial arithmetic that gen_crc64table.c follows to11 * 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 0x42F0E1EBA9EA3693ULL20#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL21 22static uint64_t crc64_table[256] = {0};23static uint64_t crc64_rocksoft_table[256] = {0};24 25static 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 else37 crc >>= 1;38 }39 table[i] = crc;40 }41}42 43static 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 else55 crc <<= 1;56 c <<= 1;57 }58 59 table[i] = crc;60 }61}62 63static 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 else72 printf(", ");73 }74 printf("};\n");75}76 77static 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 89int 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