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 reg_copy = reg;
    uint8_t bot_mask = ((1 << (8-n)) - 1);
    reg = ((bot_mask & reg) << n);
    reg |= (reg_copy >> (8-n));
    return reg;
}

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