OptHexRadixSort.m

+ (void)hexadecimalRadixSort2:(int[])input length:(int)l {
    int max = [self findMax:input length:l];
    int partiallySorted[l];
    int i;
    
    int powerOf16 = 0;
    int bin[16];
    while ((1 << (powerOf16 << 2)) < max) {
        for (int i = 0; i < 16; i++) bin[i] = 0;
        
        for (i = 0; i < l; i++) bin[(input[i] >> (powerOf16 << 2)) & 0x0f]++; // get counts of current digits
        for (i = 1; i < 16; i++) bin[i] += bin [i - 1]; // convert counts to array indices
        
        for (i = l - 1; i >= 0; i--) partiallySorted[--bin[(input[i] >> (powerOf16 << 2)) & 0x0f]] = input[i];
        for (i = 0; i < l; i++) input[i] = partiallySorted[i];
        
        powerOf16++;
    }
}