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 | #define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL |
21 | |
22 | static uint64_t crc64_table[256] = {0}; |
23 | static uint64_t crc64_rocksoft_table[256] = {0}; |
24 | |
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) |
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) |
53 | crc = (crc << 1) ^ poly; |
54 | else |
55 | crc <<= 1; |
56 | c <<= 1; |
57 | } |
58 | |
59 | table[i] = crc; |
60 | } |
61 | } |
62 | |
63 | static void output_table(uint64_t table[256]) |
64 | { |
65 | int i; |
66 | |
67 | for (i = 0; i < 256; i++) { |
68 | printf(format: "\t0x%016" PRIx64 "ULL" , table[i]); |
69 | if (i & 0x1) |
70 | printf(format: ",\n" ); |
71 | else |
72 | printf(format: ", " ); |
73 | } |
74 | printf(format: "};\n" ); |
75 | } |
76 | |
77 | static void print_crc64_tables(void) |
78 | { |
79 | printf(format: "/* this file is generated - do not edit */\n\n" ); |
80 | printf(format: "#include <linux/types.h>\n" ); |
81 | printf(format: "#include <linux/cache.h>\n\n" ); |
82 | printf(format: "static const u64 ____cacheline_aligned crc64table[256] = {\n" ); |
83 | output_table(table: crc64_table); |
84 | |
85 | printf(format: "\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n" ); |
86 | output_table(table: crc64_rocksoft_table); |
87 | } |
88 | |
89 | int main(int argc, char *argv[]) |
90 | { |
91 | generate_crc64_table(table: crc64_table, CRC64_ECMA182_POLY); |
92 | generate_reflected_crc64_table(table: crc64_rocksoft_table, CRC64_ROCKSOFT_POLY); |
93 | print_crc64_tables(); |
94 | return 0; |
95 | } |
96 | |