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