private static void ReduceEach <T>(int j, DataForReduce <T> arg)
{
var k = 1 << arg.d;
var i = 2 * j * k;
var a0 = k * (2 * j + 1) - 1;
var a1 = 2 * k * (j + 1) - 1;
arg.tmp1[a1] = arg.addop(arg.tmp0[a0], arg.tmp0[a1]);
}
public static T Reduce <T>(this T[] input, System.Func <T, T, T> addop)
{
var n = input.Length.Po2();
var tmp0 = new T[n];
var tmp1 = new T[n];
System.Array.Copy(input, tmp0, input.Length);
var dlim = Mathf.RoundToInt(Mathf.Log(n, 2f));
for (var d = 0; d < dlim; d++)
{
var j = n >> (d + 1);
var arg = new DataForReduce <T>(tmp0, tmp1, d, addop);
Parallel.For(0, j, ReduceEach, arg);
Swap(ref tmp0, ref tmp1);
}
return(tmp0[tmp0.Length - 1]);
}
