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95 lines
2.1 KiB
95 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Generate lookup table for the table-driven CRC64 calculation. |
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* |
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* gen_crc64table is executed in kernel build time and generates |
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* lib/crc64table.h. This header is included by lib/crc64.c for |
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* the table-driven CRC64 calculation. |
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* |
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* See lib/crc64.c for more information about which specification |
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* and polynomial arithmetic that gen_crc64table.c follows to |
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* generate the lookup table. |
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* |
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* Copyright 2018 SUSE Linux. |
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* Author: Coly Li <[email protected]> |
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*/ |
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#include <inttypes.h> |
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#include <stdio.h> |
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#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL |
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#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL |
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static uint64_t crc64_table[256] = {0}; |
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static uint64_t crc64_rocksoft_table[256] = {0}; |
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static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly) |
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{ |
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uint64_t i, j, c, crc; |
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for (i = 0; i < 256; i++) { |
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crc = 0ULL; |
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c = i; |
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for (j = 0; j < 8; j++) { |
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if ((crc ^ (c >> j)) & 1) |
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crc = (crc >> 1) ^ poly; |
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else |
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crc >>= 1; |
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} |
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table[i] = crc; |
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} |
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} |
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static void generate_crc64_table(uint64_t table[256], uint64_t poly) |
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{ |
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uint64_t i, j, c, crc; |
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for (i = 0; i < 256; i++) { |
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crc = 0; |
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c = i << 56; |
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for (j = 0; j < 8; j++) { |
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if ((crc ^ c) & 0x8000000000000000ULL) |
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crc = (crc << 1) ^ poly; |
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else |
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crc <<= 1; |
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c <<= 1; |
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} |
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table[i] = crc; |
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} |
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} |
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static void output_table(uint64_t table[256]) |
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{ |
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int i; |
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for (i = 0; i < 256; i++) { |
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printf("\t0x%016" PRIx64 "ULL", table[i]); |
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if (i & 0x1) |
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printf(",\n"); |
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else |
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printf(", "); |
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} |
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printf("};\n"); |
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} |
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static void print_crc64_tables(void) |
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{ |
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printf("/* this file is generated - do not edit */\n\n"); |
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printf("#include <linux/types.h>\n"); |
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printf("#include <linux/cache.h>\n\n"); |
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printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); |
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output_table(crc64_table); |
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printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n"); |
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output_table(crc64_rocksoft_table); |
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} |
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int main(int argc, char *argv[]) |
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{ |
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generate_crc64_table(crc64_table, CRC64_ECMA182_POLY); |
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generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY); |
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print_crc64_tables(); |
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return 0; |
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}
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