Merge tag 'for-5.18/block-2022-04-01' of git://git.kernel.dk/linux-block
[platform/kernel/linux-rpi.git] / lib / gen_crc64table.c
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("\t0x%016" PRIx64 "ULL", table[i]);
69                 if (i & 0x1)
70                         printf(",\n");
71                 else
72                         printf(", ");
73         }
74         printf("};\n");
75 }
76
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
89 int main(int argc, char *argv[])
90 {
91         generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);
92         generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY);
93         print_crc64_tables();
94         return 0;
95 }