Root/lib/gen_crc32table.c

1#include <stdio.h>
2#include "../include/generated/autoconf.h"
3#include "crc32defs.h"
4#include <inttypes.h>
5
6#define ENTRIES_PER_LINE 4
7
8#if CRC_LE_BITS > 8
9# define LE_TABLE_ROWS (CRC_LE_BITS/8)
10# define LE_TABLE_SIZE 256
11#else
12# define LE_TABLE_ROWS 1
13# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
14#endif
15
16#if CRC_BE_BITS > 8
17# define BE_TABLE_ROWS (CRC_BE_BITS/8)
18# define BE_TABLE_SIZE 256
19#else
20# define BE_TABLE_ROWS 1
21# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
22#endif
23
24static uint32_t crc32table_le[LE_TABLE_ROWS][256];
25static uint32_t crc32table_be[BE_TABLE_ROWS][256];
26static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
27
28/**
29 * crc32init_le() - allocate and initialize LE table data
30 *
31 * crc is the crc of the byte i; other entries are filled in based on the
32 * fact that crctable[i^j] = crctable[i] ^ crctable[j].
33 *
34 */
35static void crc32init_le_generic(const uint32_t polynomial,
36                 uint32_t (*tab)[256])
37{
38    unsigned i, j;
39    uint32_t crc = 1;
40
41    tab[0][0] = 0;
42
43    for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
44        crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
45        for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
46            tab[0][i + j] = crc ^ tab[0][j];
47    }
48    for (i = 0; i < LE_TABLE_SIZE; i++) {
49        crc = tab[0][i];
50        for (j = 1; j < LE_TABLE_ROWS; j++) {
51            crc = tab[0][crc & 0xff] ^ (crc >> 8);
52            tab[j][i] = crc;
53        }
54    }
55}
56
57static void crc32init_le(void)
58{
59    crc32init_le_generic(CRCPOLY_LE, crc32table_le);
60}
61
62static void crc32cinit_le(void)
63{
64    crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
65}
66
67/**
68 * crc32init_be() - allocate and initialize BE table data
69 */
70static void crc32init_be(void)
71{
72    unsigned i, j;
73    uint32_t crc = 0x80000000;
74
75    crc32table_be[0][0] = 0;
76
77    for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
78        crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
79        for (j = 0; j < i; j++)
80            crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
81    }
82    for (i = 0; i < BE_TABLE_SIZE; i++) {
83        crc = crc32table_be[0][i];
84        for (j = 1; j < BE_TABLE_ROWS; j++) {
85            crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
86            crc32table_be[j][i] = crc;
87        }
88    }
89}
90
91static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
92{
93    int i, j;
94
95    for (j = 0 ; j < rows; j++) {
96        printf("{");
97        for (i = 0; i < len - 1; i++) {
98            if (i % ENTRIES_PER_LINE == 0)
99                printf("\n");
100            printf("%s(0x%8.8xL), ", trans, table[j][i]);
101        }
102        printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
103    }
104}
105
106int main(int argc, char** argv)
107{
108    printf("/* this file is generated - do not edit */\n\n");
109
110    if (CRC_LE_BITS > 1) {
111        crc32init_le();
112        printf("static u32 __cacheline_aligned "
113               "crc32table_le[%d][%d] = {",
114               LE_TABLE_ROWS, LE_TABLE_SIZE);
115        output_table(crc32table_le, LE_TABLE_ROWS,
116                 LE_TABLE_SIZE, "tole");
117        printf("};\n");
118    }
119
120    if (CRC_BE_BITS > 1) {
121        crc32init_be();
122        printf("static u32 __cacheline_aligned "
123               "crc32table_be[%d][%d] = {",
124               BE_TABLE_ROWS, BE_TABLE_SIZE);
125        output_table(crc32table_be, LE_TABLE_ROWS,
126                 BE_TABLE_SIZE, "tobe");
127        printf("};\n");
128    }
129    if (CRC_LE_BITS > 1) {
130        crc32cinit_le();
131        printf("static u32 __cacheline_aligned "
132               "crc32ctable_le[%d][%d] = {",
133               LE_TABLE_ROWS, LE_TABLE_SIZE);
134        output_table(crc32ctable_le, LE_TABLE_ROWS,
135                 LE_TABLE_SIZE, "tole");
136        printf("};\n");
137    }
138
139    return 0;
140}
141

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