Set Specific Bits in a 32-bit Register

#include <stdio.h>
#include <stdint.h>
uint32_t setBits(uint32_t reg,int pos,int len){
    uint32_t mask=((1U << len) -1) << pos;
    reg |= mask;
    return reg;
}
int main(){
    uint32_t reg;
    int pos, len;
    scanf("%u %d %d", &reg, &pos, &len);
    printf("%u\n", setBits(reg,pos,len));
    return 0;

}