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lib/gen_crc32table.c
1.78 KB
1da177e4c
Linux-2.6.12-rc2
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#include <stdio.h>
#include "crc32defs.h"
#include <inttypes.h>
#define ENTRIES_PER_LINE 4
#define LE_TABLE_SIZE (1 << CRC_LE_BITS)
#define BE_TABLE_SIZE (1 << CRC_BE_BITS)
static uint32_t crc32table_le[LE_TABLE_SIZE];
static uint32_t crc32table_be[BE_TABLE_SIZE];
/**
* 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(void)
{
unsigned i, j;
uint32_t crc = 1;
crc32table_le[0] = 0;
for (i = 1 << (CRC_LE_BITS - 1); i; i >>= 1) {
crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
crc32table_le[i + j] = crc ^ crc32table_le[j];
}
}
/**
* crc32init_be() - allocate and initialize BE table data
*/
static void crc32init_be(void)
{
unsigned i, j;
uint32_t crc = 0x80000000;
crc32table_be[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[i + j] = crc ^ crc32table_be[j];
}
}
static void output_table(uint32_t table[], int len, char *trans)
{
int i;
for (i = 0; i < len - 1; i++) {
if (i % ENTRIES_PER_LINE == 0)
printf("
");
printf("%s(0x%8.8xL), ", trans, table[i]);
}
printf("%s(0x%8.8xL)
", trans, table[len - 1]);
}
int main(int argc, char** argv)
{
printf("/* this file is generated - do not edit */
");
if (CRC_LE_BITS > 1) {
crc32init_le();
printf("static const u32 crc32table_le[] = {");
output_table(crc32table_le, LE_TABLE_SIZE, "tole");
printf("};
");
}
if (CRC_BE_BITS > 1) {
crc32init_be();
printf("static const u32 crc32table_be[] = {");
output_table(crc32table_be, BE_TABLE_SIZE, "tobe");
printf("};
");
}
return 0;
}
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