Author: Tom Likens
Date: 07:51:04 02/19/03
Go up one level in this thread
On February 19, 2003 at 09:41:35, Dezhi Zhao wrote:
>On February 19, 2003 at 06:39:49, Uri Blass wrote:
>
>>I try to do movei faster and there are things that are supposed to do it
>>slightly faster but for some reasons do it slower so I deleted them(Maybe it is
>>better if I ignore it because it is a compiler optimization noise but I do not
>>like to see the program slower even if it is only 0.1% slower).
>>
>>Note that I do not use now compiler optimization except optimize for speed with
>>visual C++6.
>>
>>
>>Here is an example:
>>My function of adding pawn moves to the stack of moves get 2 numbers(from,to).
>>
>>I found that special functions to generate white moves one square forward,white
>>moves 2 pawns forward,black pawns one square forward,...helped me to do movei
>>faster.
>>
>>Common sense say that now I do not need 2 numbers in my functions because
>>I always have to=from-8 in
>>
>>Here is my function.
>>to is always from-8 and the question is if I can take advantage of that fact.
>>
>>static void gen_quietblackslowpawns(int from,int to)
>>{
>> gen_t *g;
>> if (to<=7)
>> {
>> gen_promote(from,to);
>> return;
>> }
>> g=&gen_dat[first_move[ply+1]++];
>> g->m.b.from=(char)from;
>> g->m.b.to=(char) to;
>> g->m.b.promote=0;
>> g->m.b.bits=16;
>> #if MODE!=MODE_PERFT
>> g->score = history[from][to];
>> g->index=-10000;
>> #endif
>>}
>
>I think you can get a little from that fact. It will save a few push and pop
>operations.
>
>By the way, if you really want to optimize this function, you should consider
>re-designing the b structure so that the move can be saved in a single write
>operation, instead of 4. After this optimization, you may find out this
>function is too small and fast to be a function entity, and get it inlined.
Uri,
One of the things I did to speed this up in my program was to store a
move in an unsigned integer and use bit operations (shifts, ANDs, ORs)
to access the various fields. For example, I stored the 'from/to' fields
in the lower 12-bits and then declared my history arrays as
w_history[4096]
b_history[4096]
instead of w_history[64][64]. Then when I wanted to update one of
the arrays, it was just a simply AND operation to get the index into
the table. Also copying moves becomes much faster, etc.
regards,
--tom
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