diff options
Diffstat (limited to 'lib/gen_crc32table.c')
-rw-r--r-- | lib/gen_crc32table.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c new file mode 100644 index 00000000..85d0e412 --- /dev/null +++ b/lib/gen_crc32table.c @@ -0,0 +1,99 @@ +#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[4][LE_TABLE_SIZE]; +static uint32_t crc32table_be[4][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] = 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[0][i + j] = crc ^ crc32table_le[0][j]; + } + for (i = 0; i < LE_TABLE_SIZE; i++) { + crc = crc32table_le[0][i]; + for (j = 1; j < 4; j++) { + crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); + crc32table_le[j][i] = crc; + } + } +} + +/** + * 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 < 4; j++) { + crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8); + crc32table_be[j][i] = crc; + } + } +} + +static void output_table(uint32_t table[4][256], int len, char *trans) +{ + int i, j; + + for (j = 0 ; j < 4; 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 const u32 crc32table_le[4][256] = {"); + output_table(crc32table_le, LE_TABLE_SIZE, "tole"); + printf("};\n"); + } + + if (CRC_BE_BITS > 1) { + crc32init_be(); + printf("static const u32 crc32table_be[4][256] = {"); + output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); + printf("};\n"); + } + + return 0; +} |