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
    uint32_t ret_val = (reg & 0b1);
    while(reg){
        ret_val <<= 1;
        reg >>=2;
        ret_val |= (reg & 0b1);
    }
    ret_val >>= 1;
    return ret_val;
}

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