Author: Bernd Nürnberger
Date: 05:49:11 05/06/04
Go up one level in this thread
On May 06, 2004 at 08:43:20, James Swafford wrote:
>On May 06, 2004 at 07:07:57, Bernd Nürnberger wrote:
>
>>Hello,
>>
>>I have a really strange bug in my move generator, but in the meantime,
>>after thourough debugging, I am more and more convinced, that it is not
>>a bug in my programming but a bug in Java itself or in the OS/Hardware
>>(but I am still hoping, I made a mistake somewhere ...).
>>
>>I have a iBook 300, Mac OS 9.x, and the latest Java for Mac OS 9.x (I think
>>its MRJ SDK 2.2.4 or so).
>>
>>HERE COMES THE PROBLEM:
>>
>>Some 64 bit long values behave really strange: the upper part (the 32 MSBs)
>>are trashed from time to time (lower 32 bits are OK, upper 32 bits seem
>>more or less random). I looked through the code again and again, so that
>>all literals have a "L" appended, and all literals seems ok now.
>>
>>Could it be, that some operators in Java on long values are not properly
>>implemented and make errors on certain circumstances? Maybe a set upper
>>bit (64th bit, sign bit) causes problems in some cases?
>>
>>I would be really glad to hear your thoughts are even solutions to this
>>kind of problem.
>>
>>Many many thanks in advance for your answers!
>
>My SWAG: your 'trash' in the upper 32 bits are coming from
>an OR op. You're sure all your bitboards are properly
>initialized?
>
>Hard to say any more without looking over code. :-/
>
>--
>James
Thanks for this hint. I will also try to get a good Java
Debugger to get deeper into this problem. More strangly is the
behaviour that, if I output blackLegalMoves, for instance,
I get correct values!!
--- snippet ---
// k -- black king
/////////////////////
from = board.blackKing;
mvboard = KING_MOVES[from] & blackLegalMoves;
halfply = from | Move.BPC_KING;
while (mvboard != 0L) {
to = Bitboard.last(mvboard);
mvboard &= Bitboard.CLEAR_MASK[to];
moves[mvidx++] = halfply | to << Move.TO | piece[to] << Move.CAPTY;
}
--- snippet ---
Greetings, Bernd
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