Extract Even Bits Only from 32-bit Register

#include <stdio.h>
#include <stdint.h>
#define SET(reg, pos) reg |= (1 << pos)
#define CLEAR(reg, pos) reg &= ~(1 << pos)
uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint32_t out = 0;
    for(int i = 0, j = 0; i < 32; i += 2, j++){
        if((reg >> i) & 1){
            SET(out, j);
        }
        
    }
    return out;
}

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

Solving Approach