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Use a static CRC8 table

This commit is contained in:
Arun Prakash Jana 2019-02-06 01:04:35 +05:30
parent cebb2469d3
commit 22b95be810
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GPG Key ID: A75979F35C080412
1 changed files with 26 additions and 4 deletions
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30
src/nnn.c
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@ -331,9 +331,6 @@ static size_t g_tmpfplen; /* path to tmp files for copy without X, keybind help
static uchar g_crc;
static uchar BLK_SHIFT = 9;
/* CRC data */
static uchar crc8table[CRC8_TABLE_LEN] __attribute__ ((aligned));
/* For use in functions which are isolated and don't return the buffer */
static char g_buf[CMD_LEN_MAX] __attribute__ ((aligned));
@ -481,6 +478,7 @@ static int (*nftw_fn) (const char *fpath, const struct stat *sb, int typeflag, s
* CRC8 source:
* https://barrgroup.com/Embedded-Systems/How-To/CRC-Calculation-C-Code
*/
#if 0 // using a static table
static void crc8init()
{
uchar remainder, bit;
@ -504,12 +502,34 @@ static void crc8init()
crc8table[dividend] = remainder;
}
}
#endif
static uchar crc8fast(uchar const message[], size_t n)
{
static uchar data, remainder;
static size_t byte;
/* CRC data */
static const uchar crc8table[CRC8_TABLE_LEN] __attribute__ ((aligned)) =
{
0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53,
};
/* Divide the message by the polynomial, a byte at a time */
for (remainder = byte = 0; byte < n; ++byte) {
data = message[byte] ^ (remainder >> (WIDTH - 8));
@ -1222,7 +1242,7 @@ static int xstrverscmp(const char * const s1, const char * const s2)
/* S_Z */ S_N, S_F, S_Z
};
static const int8_t result_type[] =
static const int8_t result_type[] __attribute__ ((aligned)) =
{
/* state x/x x/d x/0 d/x d/d d/0 0/x 0/d 0/0 */
@ -4185,7 +4205,9 @@ int main(int argc, char *argv[])
/* Set locale */
setlocale(LC_ALL, "");
#if 0
crc8init();
#endif
/* Bind TAB to cycling */
rl_variable_bind("completion-ignore-case", "on");