ia64/linux-2.6.18-xen.hg

view lib/gen_crc32table.c @ 0:831230e53067

Import 2.6.18 from kernel.org tarball.
author Ian Campbell <ian.campbell@xensource.com>
date Wed Apr 11 14:15:44 2007 +0100 (2007-04-11)
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1 #include <stdio.h>
2 #include "crc32defs.h"
3 #include <inttypes.h>
5 #define ENTRIES_PER_LINE 4
7 #define LE_TABLE_SIZE (1 << CRC_LE_BITS)
8 #define BE_TABLE_SIZE (1 << CRC_BE_BITS)
10 static uint32_t crc32table_le[LE_TABLE_SIZE];
11 static uint32_t crc32table_be[BE_TABLE_SIZE];
13 /**
14 * crc32init_le() - allocate and initialize LE table data
15 *
16 * crc is the crc of the byte i; other entries are filled in based on the
17 * fact that crctable[i^j] = crctable[i] ^ crctable[j].
18 *
19 */
20 static void crc32init_le(void)
21 {
22 unsigned i, j;
23 uint32_t crc = 1;
25 crc32table_le[0] = 0;
27 for (i = 1 << (CRC_LE_BITS - 1); i; i >>= 1) {
28 crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
29 for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
30 crc32table_le[i + j] = crc ^ crc32table_le[j];
31 }
32 }
34 /**
35 * crc32init_be() - allocate and initialize BE table data
36 */
37 static void crc32init_be(void)
38 {
39 unsigned i, j;
40 uint32_t crc = 0x80000000;
42 crc32table_be[0] = 0;
44 for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
45 crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
46 for (j = 0; j < i; j++)
47 crc32table_be[i + j] = crc ^ crc32table_be[j];
48 }
49 }
51 static void output_table(uint32_t table[], int len, char *trans)
52 {
53 int i;
55 for (i = 0; i < len - 1; i++) {
56 if (i % ENTRIES_PER_LINE == 0)
57 printf("\n");
58 printf("%s(0x%8.8xL), ", trans, table[i]);
59 }
60 printf("%s(0x%8.8xL)\n", trans, table[len - 1]);
61 }
63 int main(int argc, char** argv)
64 {
65 printf("/* this file is generated - do not edit */\n\n");
67 if (CRC_LE_BITS > 1) {
68 crc32init_le();
69 printf("static const u32 crc32table_le[] = {");
70 output_table(crc32table_le, LE_TABLE_SIZE, "tole");
71 printf("};\n");
72 }
74 if (CRC_BE_BITS > 1) {
75 crc32init_be();
76 printf("static const u32 crc32table_be[] = {");
77 output_table(crc32table_be, BE_TABLE_SIZE, "tobe");
78 printf("};\n");
79 }
81 return 0;
82 }