NibbleSort-Vetter

static const unsigned long counting_table[16 * 16];
static const unsigned long result_table[16 * 16 * 8];
static const unsigned char shifting_table[16 *16];

void counting_nibble_sort_lookup(unsigned long* buf)
{
    for (int num = 0; num < 1024; num++) {
        unsigned long value = buf[num];
        unsigned long count = 0;
        for (int i = 0; i < 16; i += 2)
            count += counting_table[(value >> (i * 4)) & 0xFF];

    if ((count & (count - 1)) == 0)
            continue;

        unsigned long result = 0;
        for (int i = 0; i < 16; i += 2) {
            int double_nibble_count = ((count >> (56 - 4 * i)) & 0xFF);
            result <<= shifting_table[double_nibble_count];
            result |= result_table[double_nibble_count + i * 16 * 8];
        }
        buf[num] = result;
    }
}