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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 | 19 | #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL |
cbc0a40e | 20 | #define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL |
feba04fd CL |
21 | |
22 | static uint64_t crc64_table[256] = {0}; | |
cbc0a40e | 23 | static uint64_t crc64_rocksoft_table[256] = {0}; |
feba04fd | 24 | |
cbc0a40e KB |
25 | static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly) |
26 | { | |
27 | uint64_t i, j, c, crc; | |
28 | ||
29 | for (i = 0; i < 256; i++) { | |
30 | crc = 0ULL; | |
31 | c = i; | |
32 | ||
33 | for (j = 0; j < 8; j++) { | |
34 | if ((crc ^ (c >> j)) & 1) | |
35 | crc = (crc >> 1) ^ poly; | |
36 | else | |
37 | crc >>= 1; | |
38 | } | |
39 | table[i] = crc; | |
40 | } | |
41 | } | |
42 | ||
43 | static void generate_crc64_table(uint64_t table[256], uint64_t poly) | |
feba04fd CL |
44 | { |
45 | uint64_t i, j, c, crc; | |
46 | ||
47 | for (i = 0; i < 256; i++) { | |
48 | crc = 0; | |
49 | c = i << 56; | |
50 | ||
51 | for (j = 0; j < 8; j++) { | |
52 | if ((crc ^ c) & 0x8000000000000000ULL) | |
cbc0a40e | 53 | crc = (crc << 1) ^ poly; |
feba04fd CL |
54 | else |
55 | crc <<= 1; | |
56 | c <<= 1; | |
57 | } | |
58 | ||
cbc0a40e | 59 | table[i] = crc; |
feba04fd CL |
60 | } |
61 | } | |
62 | ||
cbc0a40e | 63 | static void output_table(uint64_t table[256]) |
feba04fd CL |
64 | { |
65 | int i; | |
66 | ||
feba04fd | 67 | for (i = 0; i < 256; i++) { |
cbc0a40e | 68 | printf("\t0x%016" PRIx64 "ULL", table[i]); |
feba04fd CL |
69 | if (i & 0x1) |
70 | printf(",\n"); | |
71 | else | |
72 | printf(", "); | |
73 | } | |
74 | printf("};\n"); | |
75 | } | |
76 | ||
cbc0a40e KB |
77 | static void print_crc64_tables(void) |
78 | { | |
79 | printf("/* this file is generated - do not edit */\n\n"); | |
80 | printf("#include <linux/types.h>\n"); | |
81 | printf("#include <linux/cache.h>\n\n"); | |
82 | printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); | |
83 | output_table(crc64_table); | |
84 | ||
85 | printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n"); | |
86 | output_table(crc64_rocksoft_table); | |
87 | } | |
88 | ||
feba04fd CL |
89 | int main(int argc, char *argv[]) |
90 | { | |
cbc0a40e KB |
91 | generate_crc64_table(crc64_table, CRC64_ECMA182_POLY); |
92 | generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY); | |
93 | print_crc64_tables(); | |
feba04fd CL |
94 | return 0; |
95 | } |