22. Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    uint32_t even_bits = 0x0;

    for (uint8_t i = 0; i < 16; i++) {
        uint32_t cur = (reg >> (2 * i)) & 0x01;
        even_bits |= ((cur & 0x0F) << i);
    }

    return even_bits;
}

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