31. Rotate Left in an 8-bit Register

#include <stdio.h>
#include <stdint.h>

uint8_t rotate_left(uint8_t reg, uint8_t n) {
    // Your code here
    uint8_t buff = 0;
    n = n%8;
    uint8_t mask = ((1<<n)-1) << 8-n;
    buff = reg & mask;
    buff >>= 8-n;
    reg <<= n;
    reg |= buff;
    return reg;
}

int main() {
    uint8_t reg, n;
    scanf("%hhu %hhu", &reg, &n);
    printf("%u", rotate_left(reg, n));
    return 0;
}