Compress Interleaved Bits Reverse Bit Spreading

Code

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

uint8_t compress_bits(uint16_t val) {
    int b;
    int res;
    for (int i=0;i<8;i++)
        {
            b = (val >> (2*i)) & 1;
            res |= (b << i);
        }
    return res;
}

int main() {
    uint16_t val;
    scanf("%hu", &val);

    uint8_t result = compress_bits(val);
    printf("%u", result);
    return 0;
}

Solving Approach