[C] Invertire il valore binario di una variabile

[andbin]

Semplice:

unsigned int bit_reverse (unsigned int val)
{
    unsigned int res = 0;
    int i;
    for (i = 0; i < sizeof(unsigned int)*8; i++, val>>=1)
        res = res << 1 | (val & 1);
    return res;
}