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 = (1U << n) -1;
    uint8_t new_reg = (reg & (mask << (8-n)));
    reg = reg << n;
    new_reg >>=(8-n);
    reg |= new_reg;
    return reg;
}

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