Author: Uri Blass
Date: 11:09:56 01/03/03
Go up one level in this thread
On January 03, 2003 at 14:04:23, Ricardo Gibert wrote:
>On January 03, 2003 at 12:03:45, Uri Blass wrote:
>
>>code B is slightly faster than code A.
>>I know that side can get only 0 or 1(something that the compiler does not know)
>>and B is eqvivalent to A if you assume that side gets only 0 or 1.
>>
>>Is it possible to write a third code that will be even faster than B?
>>
>>I think that if the compiler can know that side is or 0 or 1 it can do B even
>>faster.
>>
>>code A:
>>
>>if (side==LIGHT)
>>{
>> if (to>=56)
>> {
>> gen_promote(from,to,bits);
>> return;
>> }
>>}
>>else
>>{
>> if (to<=7)
>> {
>> gen_promote(from,to,bits);
>> return;
>> }
>>}
>
>
>Try something like this:
>
>if ((to<=7) || (to>=56))
> {
> gen_promote(from,to,bits);
> return;
> }
>
>
>Note: Above is untested.
>
>I've assumed from "gen_promote(from,to,bits)" that this code is executed for
>pawn moves only and is intended to test whether promotions should be generated.
>
>The test "side==LIGHT" is not neccessary since, the test "to>=56" can only be
>true if it is Whites move (white pawns can't move to the squares 0 thru 7) and
>for "to<=7" the reasoning is analogous.
>
>I've also assumed that "to<=7" is false even more often than "to>=56", so I
>placed it first. White has the advantage of the first move after all!
You are right.
Thanks
I did not think about that simple fact but I still think that I can earn more
speed from having 2 different codes for white and black because in this case
I can even avoid if ((to<=7) || (to>=56)) and use only one condition inside the
if and I already know before calling the function if it is white or black.
Uri
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