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