Set Specific Bits in a 32-bit Register

Code

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

#define SHIFT(n) (1 << n) 

uint32_t set_bits(uint32_t reg, uint8_t pos, uint8_t len) {
    int counter = 0; 
    for (int i = 0; i < len; i++){ 
        reg |= SHIFT(pos + counter); 
        counter += 1; 
    }
    return reg;
}

int main() {
    uint32_t reg;
    uint8_t pos, len;
    scanf("%u %hhu %hhu", &reg, &pos, &len);
    printf("%u", set_bits(reg, pos, len));
    return 0;
}

Solving Approach