Extract Even Bits Only from 32-bit Register

Code

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

uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint32_t res = 0;
    uint32_t mask = (1U <<31);
    reg <<=1;
    while(reg > 0)
    {
        res <<= 1;
        if(reg & mask)
        {
            res |= 1;  
        }
        reg <<= 2;

    }
    return res;
}

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

Solving Approach