| 1 | #include <stdio.h> |
| 2 | #include <stdint.h> |
| 3 | #include <stdlib.h> |
| 4 | #include <string.h> |
| 5 | #include <sys/time.h> |
| 6 |
|
| 7 | uint64_t us(void) { |
| 8 | uint64_t us; |
| 9 | struct timeval lnm_current_time; |
| 10 | gettimeofday(&lnm_current_time, NULL); |
| 11 | us = (lnm_current_time.tv_sec * 1000000ULL + lnm_current_time.tv_usec); |
| 12 | return us; |
| 13 | } |
| 14 |
|
| 15 | uint8_t bit_read(uint8_t bytes[], uint8_t pos) { |
| 16 | return bytes[pos >> 3] >> (pos & 7) & 1; |
| 17 | } |
| 18 |
|
| 19 | void bit_toggle(uint8_t bytes[], uint8_t pos) { |
| 20 | // byte = pos >> 3 == pos / 8 |
| 21 | // bit = pos & 7 == pos % 8 |
| 22 | // bit_select = 1 << bit |
| 23 | bytes[pos >> 3] ^= 1 << (pos & 7); |
| 24 | } |
| 25 |
|
| 26 | void print(uint8_t bytes[], uint8_t byte_count) { |
| 27 | for (unsigned short pos = 0; pos < byte_count * 8; pos++) { |
| 28 | printf("%c", 48 + bit_read(bytes, pos)); |
| 29 | } |
| 30 | putchar('\n'); |
| 31 | } |
| 32 |
|
| 33 | int main(){ |
| 34 | uint64_t a = us(); |
| 35 | uint8_t byte_count = 8; |
| 36 | srand(a); |
| 37 | uint64_t iter = rand() % 10000000; |
| 38 | uint8_t bytes[byte_count]; |
| 39 | memset(bytes, 0, byte_count); |
| 40 | for (uint64_t i = 0; i < iter; i++) { |
| 41 | bit_toggle(bytes, (bytes[0] ^ i) & (byte_count * 8 - 1)); |
| 42 | } |
| 43 | print(bytes, byte_count); |
| 44 | uint64_t elapsed = us() - a; |
| 45 | printf("Time elapsed: %luus (%fus per operation)\n", elapsed, elapsed/(float)iter); |
| 46 | return 0; |
| 47 | } |
| 48 |
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