22. Extract Even Bits Only from 32-bit Register

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

#define PATTERN_MASK        0x55555555
#define PATTERN_CLEANUP     0x0000FFFF

uint32_t extract_even_bits(uint32_t reg) { 
    uint32_t result = 0;
    for (uint32_t maskIndex = 0; maskIndex < 32; maskIndex+=2)
    {
        result = result | ((reg & (1 << maskIndex)) >> (maskIndex/2));
    }

    return result;
}

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