Author: Uri Blass
Date: 03:35:26 06/20/01
Go up one level in this thread
On June 20, 2001 at 05:26:48, Daniel Clausen wrote:
>Hi
>
>On June 20, 2001 at 04:36:44, Uri Blass wrote:
>>I use the perft command in crafty in order to debug my move generator.
>>
>>I found that perft 4 gave me correct result when perft 5 does not give me
>>correct result and I got 4865621 instead of 4865609.
>>
>>After finding it
>>I calculated the perft 4 after every legal move and found that perft 4 does not
>>give correct result after 1.d3
>>
>>After finding it I checked perft 3 after d3 to see where my program is wrong
>>and found that after 1.d3 c5 I got 15972 instead of 15971.
>>
>>I now need to continue in this way to check where is the error.
>
>Personally I found the position/numbers given in KiwiPete's finger notes on CCC
>to be extremely useful to debug my move generator:
>
> 6: The following position is a move generation test. Listed are the number
> of different games from that position to ply 1,2,3,4, and 5.
> 7: r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -
> 8: 48; 2,039; 97,862; 4,085,603; 193,690,690
>
>The position includes all move-types I could think of, which the initial
>position obviously doesn't. (ie promotion, castling after 5 plies) Obviously a
>'setup position' feature is needed to use this though..
Setup positions is not needed
The following loop is enough to generate every legal position.
while (ply<numplies)
{
gen();
makemove(gen_dat[first_move[ply]+a[ply]].m.b);
}
The only problem is to calculate the game that gives the position
and to calculate the array a[ply](for example 1.e4 means a[0]=11 in my program)
so it may be faster to generate setup position function.
I can add that I corrected the mistake of assuming that
1.d3 c5 2.Kd2 Qa5 3.Ke1 is a leagl game so perft 5 gives correct result for the
initial position.
My mistake was that I used ~x instead of x==0(I have no variable with the name x
in my program and I used a long expression).
x is truth but the problem is that ~x is also not 0 and is also truth.
Uri
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