18. Set Multiple Bits in 8-bit Register

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

uint8_t set_range(uint8_t reg, uint8_t start, uint8_t end) {
    // Your code here
    // for(int i = start; i <= end; i++){
    //     reg |= 1 << i;
    // }
    if ( start > end || end >= 8){
        return reg;
    }
    uint8_t mask;
    uint8_t width;

    width = end - start + 1;
    mask = ((1 << width) - 1) << start;

    return reg | mask;
}

int main() {
    uint8_t reg, start, end;
    scanf("%hhu %hhu %hhu", &reg, &start, &end);
    printf("%u", set_range(reg, start, end));
    return 0;
}