randomShuffle

[Diggory]

Here's the fixed one:

uint[] randomSample(uint N, uint M) {
	uint[] result = new uint[N];

	struct hashPair {
		uint key;
		uint index;
	}

	size_t tableSize = N*4;
	if (tableSize > M)
		tableSize = M;

	hashPair[] table = new hashPair[tableSize];

	for (uint i = 0; i < N; ++i) {
		uint v = (rndGen.front % (M-i))+i;
		uint newv = v, newi = i;
		rndGen.popFront();

		uint ihash = i%tableSize;
		while (table[ihash].index) {
			if (table[ihash].key == i) {
				newi = table[ihash].index-1;
				break;
			}
		}

		uint vhash = v%tableSize;

		while (table[vhash].index) {
			if (table[vhash].key == v) {
				newv = table[vhash].index-1;
				table[vhash].index = newi+1;
				goto done;
			}

			vhash = (vhash+1)%tableSize;
		}

		table[vhash].key = v;
		table[vhash].index = newi+1;

done:
		result[i] = newv;
	}

	return result;
}


Still a few places to optimise, and I think the compiler 
optimisation should be able to give a decent speed up as well. 
Would be interested to see how it compares in your benchmark!