Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    uint32_t result = 0U;
    uint32_t mask = 1U;
    uint32_t bit_value;

    for (int pos = 0; pos < 16; pos++) {
        // read the bit at even position of reg
        bit_value = (reg >> 2*pos) & mask;

        // set this bit at correct position in result
        result |= bit_value << pos;
    }
    return result;
}

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