aboutsummaryrefslogtreecommitdiffstats
path: root/lib/gen_crc32table.c
blob: 71fcfcd964104f732c0e9c3ac0af45620fd438b7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
#include <stdio.h>
#include "../include/generated/autoconf.h"
#include "crc32defs.h"
#include <inttypes.h>

#define ENTRIES_PER_LINE 4

#if CRC_LE_BITS > 8
# define LE_TABLE_ROWS (CRC_LE_BITS/8)
# define LE_TABLE_SIZE 256
#else
# define LE_TABLE_ROWS 1
# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
#endif

#if CRC_BE_BITS > 8
# define BE_TABLE_ROWS (CRC_BE_BITS/8)
# define BE_TABLE_SIZE 256
#else
# define BE_TABLE_ROWS 1
# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
#endif

static uint32_t crc32table_le[LE_TABLE_ROWS][256];
static uint32_t crc32table_be[BE_TABLE_ROWS][256];
static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];

/**
 * crc32init_le() - allocate and initialize LE table data
 *
 * crc is the crc of the byte i; other entries are filled in based on the
 * fact that crctable[i^j] = crctable[i] ^ crctable[j].
 *
 */
static void crc32init_le_generic(const uint32_t polynomial,
				 uint32_t (*tab)[256])
{
	unsigned i, j;
	uint32_t crc = 1;

	tab[0][0] = 0;

	for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
		crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
		for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
			tab[0][i + j] = crc ^ tab[0][j];
	}
	for (i = 0; i < LE_TABLE_SIZE; i++) {
		crc = tab[0][i];
		for (j = 1; j < LE_TABLE_ROWS; j++) {
			crc = tab[0][crc & 0xff] ^ (crc >> 8);
			tab[j][i] = crc;
		}
	}
}

static void crc32init_le(void)
{
	crc32init_le_generic(CRCPOLY_LE, crc32table_le);
}

static void crc32cinit_le(void)
{
	crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
}

/**
 * crc32init_be() - allocate and initialize BE table data
 */
static void crc32init_be(void)
{
	unsigned i, j;
	uint32_t crc = 0x80000000;

	crc32table_be[0][0] = 0;

	for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
		crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
		for (j = 0; j < i; j++)
			crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
	}
	for (i = 0; i < BE_TABLE_SIZE; i++) {
		crc = crc32table_be[0][i];
		for (j = 1; j < BE_TABLE_ROWS; j++) {
			crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
			crc32table_be[j][i] = crc;
		}
	}
}

static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
{
	int i, j;

	for (j = 0 ; j < rows; j++) {
		printf("{");
		for (i = 0; i < len - 1; i++) {
			if (i % ENTRIES_PER_LINE == 0)
				printf("\n");
			printf("%s(0x%8.8xL), ", trans, table[j][i]);
		}
		printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
	}
}

int main(int argc, char** argv)
{
	printf("/* this file is generated - do not edit */\n\n");

	if (CRC_LE_BITS > 1) {
		crc32init_le();
		printf("static u32 __cacheline_aligned "
		       "crc32table_le[%d][%d] = {",
		       LE_TABLE_ROWS, LE_TABLE_SIZE);
		output_table(crc32table_le, LE_TABLE_ROWS,
			     LE_TABLE_SIZE, "tole");
		printf("};\n");
	}

	if (CRC_BE_BITS > 1) {
		crc32init_be();
		printf("static u32 __cacheline_aligned "
		       "crc32table_be[%d][%d] = {",
		       BE_TABLE_ROWS, BE_TABLE_SIZE);
		output_table(crc32table_be, LE_TABLE_ROWS,
			     BE_TABLE_SIZE, "tobe");
		printf("};\n");
	}
	if (CRC_LE_BITS > 1) {
		crc32cinit_le();
		printf("static u32 __cacheline_aligned "
		       "crc32ctable_le[%d][%d] = {",
		       LE_TABLE_ROWS, LE_TABLE_SIZE);
		output_table(crc32ctable_le, LE_TABLE_ROWS,
			     LE_TABLE_SIZE, "tole");
		printf("};\n");
	}

	return 0;
}