18. Set Multiple Bits in 8-bit Register

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

#define MASK(width, pos) (((1<<width)-1) << pos)

uint8_t set_range(uint8_t reg, uint8_t start, uint8_t end) {
    // Aproach 1:
    // for (int i =start; i <= end; i++){
    //     reg |= (1U << i);
    // }

    //Aproach 2:
    int width = (end - start)+1;  //include of endpoints
    reg |= MASK(width, start);

    return reg;
}

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