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feba04fd CL |
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 | ||
feba04fd CL |
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 | } |