public static int FindMoveIndex(MGMove[] moves, ConverterMGMoveEncodedMove.FromTo moveSquares, int startIndex, int numMovesUsed)
{
short fromAndTo = moveSquares.FromAndToCombined;
// partially unroll the loop to improve instruction-level parallelism
int i = startIndex;
while (i < numMovesUsed - 3)
{
if (moves[i].FromAndToCombined == fromAndTo)
{
return(i);
}
if (moves[i + 1].FromAndToCombined == fromAndTo)
{
return(i + 1);
}
if (moves[i + 2].FromAndToCombined == fromAndTo)
{
return(i + 2);
}
if (moves[i + 3].FromAndToCombined == fromAndTo)
{
return(i + 3);
}
i += 4;
}
while (i < numMovesUsed)
{
if (moves[i].FromAndToCombined == fromAndTo)
{
return(i);
}
i++;
}
return(-1);
}
// --------------------------------------------------------------------------------------------
internal unsafe static int FindMoveIndexAVX(MGMove[] moves, ConverterMGMoveEncodedMove.FromTo moveSquares, int startIndex, int numMovesUsed)
{
// Use non-AVX version if few move to check
if (numMovesUsed - startIndex < 12)
{
return(MoveInMGMovesArrayLocator.FindMoveIndex(moves, moveSquares, startIndex, numMovesUsed));
}
void * ptrStart = Unsafe.AsPointer(ref moves[0]);
Span <int> ints = new Span <int>(ptrStart, numMovesUsed);
int foundIndex = FindIndexOfShortAtEvenIndexHavingValue(ints, moveSquares.FromAndToCombined, startIndex, numMovesUsed - 1);
if (foundIndex == -2)
{
// The AVX routine found a false pseudo-match at odd index
// Fallback to non AVX version
// This is expected to happen only very rarely
return(MoveInMGMovesArrayLocator.FindMoveIndex(moves, moveSquares, startIndex, numMovesUsed));
}
return(foundIndex);
}
