Radix Sort, the value of r

Please refer to the following code for radix sort:

class RadixSort
{
    public static void radix_sort_uint(int[] a, int bits)
    {

        int[] b = new int[a.length];
        int[] b_orig = b;


        int rshift = 0;
        for (int mask = ~(-1 << bits); mask != 0; mask <<= bits, rshift += bits) {

            int[] cntarray = new int[1 << bits];

            for (int p = 0; p < a.length; ++p) {
                int key = (a[p] & mask) >> rshift;
                ++cntarray[key];
            }


        for (int i = 1; i < cntarray.length; ++i)
                        cntarray[i] += cntarray[i-1];


            for (int p = a.length-1; p >= 0; --p) {
                int key = (a[p] & mask) >> rshift;
                --cntarray[key];
                b[cntarray[key]] = a[p];
            }


            int[] temp = b; b = a; a = temp;
        }


        if (a == b_orig)
            System.arraycopy(a, 0, b, 0, a.length);
    }
}

This is downloaded from wikipedia.

I feel that the algorithm will work only for value of bits parameter that divide 32 perfectly. Thus, bits should be something like 2 or 4 , but not 10. P开发者_开发百科lease let me know if I am right.

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Short answer: No

Long answer:

The probable line of confusion is:

for (int mask = ~(-1 << bits); mask != 0; mask <<= bits, rshift += bits) {

mask <<= bits shifts the bits of mask left by bits, padding the right with zeros. If bits doesn't divide 32, then the full 32 bits won't be utilised. So while bits should divide 32, choosing a value that doesn't does not break the code.