67 lines
1.4 KiB
C
67 lines
1.4 KiB
C
// 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 <colyli@suse.de>
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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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static uint64_t crc64_table[256] = {0};
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static void generate_crc64_table(void)
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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) ^ CRC64_ECMA182_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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crc64_table[i] = crc;
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}
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}
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static void print_crc64_table(void)
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{
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int i;
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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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for (i = 0; i < 256; i++) {
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printf("\t0x%016" PRIx64 "ULL", crc64_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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int main(int argc, char *argv[])
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{
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generate_crc64_table();
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print_crc64_table();
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return 0;
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}
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