Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    unsigned int reg_val = 0;
    int mask = 0;
    for(int i = 0; i<16; i++)
    {
        mask = (reg >> (i * 2)) & 1U;
        reg_val |= (mask << i);
    }
    return reg_val;
}

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