Set Specific Bits in a 32-bit Register

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

uint32_t set_bits(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    int n = pos + len;
    uint32_t mask= 1;
    n--;
    for(int i =0;i<len;i++)
    {
        mask = (1<<n);
        reg = reg |mask;

        n--;
        mask =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;
}