gen_crc32table.c

 1// SPDX-License-Identifier: GPL-2.0
 2#include <stdio.h>
 3#include "../../include/linux/crc32poly.h"
 4#include "../../include/generated/autoconf.h"
 5#include <inttypes.h>
 6
 7static uint32_t crc32table_le[256];
 8static uint32_t crc32table_be[256];
 9static uint32_t crc32ctable_le[256];
10
11/**
12 * crc32init_le() - allocate and initialize LE table data
13 *
14 * crc is the crc of the byte i; other entries are filled in based on the
15 * fact that crctable[i^j] = crctable[i] ^ crctable[j].
16 *
17 */
18static void crc32init_le_generic(const uint32_t polynomial, uint32_t tab[256])
19{
20	unsigned i, j;
21	uint32_t crc = 1;
22
23	tab[0] = 0;
24
25	for (i = 128; i; i >>= 1) {
26		crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
27		for (j = 0; j < 256; j += 2 * i)
28			tab[i + j] = crc ^ tab[j];
29	}
30}
31
32static void crc32init_le(void)
33{
34	crc32init_le_generic(CRC32_POLY_LE, crc32table_le);
35}
36
37static void crc32cinit_le(void)
38{
39	crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
40}
41
42/**
43 * crc32init_be() - allocate and initialize BE table data
44 */
45static void crc32init_be(void)
46{
47	unsigned i, j;
48	uint32_t crc = 0x80000000;
49
50	crc32table_be[0] = 0;
51
52	for (i = 1; i < 256; i <<= 1) {
53		crc = (crc << 1) ^ ((crc & 0x80000000) ? CRC32_POLY_BE : 0);
54		for (j = 0; j < i; j++)
55			crc32table_be[i + j] = crc ^ crc32table_be[j];
56	}
57}
58
59static void output_table(const uint32_t table[256])
60{
61	int i;
62
63	for (i = 0; i < 256; i += 4) {
64		printf("\t0x%08x, 0x%08x, 0x%08x, 0x%08x,\n",
65		       table[i], table[i + 1], table[i + 2], table[i + 3]);
66	}
67}
68
69int main(int argc, char** argv)
70{
71	printf("/* this file is generated - do not edit */\n\n");
72
73	crc32init_le();
74	printf("static const u32 ____cacheline_aligned crc32table_le[256] = {\n");
75	output_table(crc32table_le);
76	printf("};\n");
77
78	crc32init_be();
79	printf("static const u32 ____cacheline_aligned crc32table_be[256] = {\n");
80	output_table(crc32table_be);
81	printf("};\n");
82
83	crc32cinit_le();
84	printf("static const u32 ____cacheline_aligned crc32ctable_le[256] = {\n");
85	output_table(crc32ctable_le);
86	printf("};\n");
87
88	return 0;
89}