31. Rotate Left in an 8-bit Register

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

uint8_t rotate_left(uint8_t reg, uint8_t n) {

    uint8_t mask = (((1 << n) - 1) << (8 - n)) & reg;
    reg <<= n;
    mask >>= (8-n);
    reg |= mask ;

    return reg;
}

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