Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint16_t res =0;
    while(reg!=0){
        if(reg & 0x01){
            res = res<<1;
            res|=0x01;
            reg = reg>>2;
        }
        else{
            res = res<<1;
            res|=0x00;
            reg = reg>>2; 
        }
    }
    return res;
}

int main() {
    uint32_t reg;
    scanf("%u", &reg);
    printf("%u", extract_even_bits(reg));
    return 0;
}