Author: Uri Blass
Date: 14:41:26 02/19/04
Go up one level in this thread
On February 19, 2004 at 16:22:30, Gerd Isenberg wrote:
>On February 19, 2004 at 14:39:16, Uri Blass wrote:
>
>>Today I have an array direction[64][64] that gives me different numbers for
>>different directions(possible directions are queen direction that get 0-7 knight
>>directions that get -2,identical squares that get -9 or no direction that gets
>>-1 ).
>>
>>I thought about the idea to change it to the following definition:
>>
>>#define direction((i)(j)) directionnumber[translate[i]-translate[j]+128]
>>
>>The result is that I can get instead of one array of 4096 entries
>>2 arrays when translate is an array of 64 entries and directionnumber is an
>>array of 256 entries.
>>
>>My question is if it is a good idea from speed point of view.
>>It will probably be a simple change when I only need to construct the 2 arrays
>>and the main problem is to construct the translate array.
>>
>>It is probably only few hours of work but I do not like to spend time on
>>constructing these arrays only to discover later that it is not productive so I
>>ask for your opinion about it.
>>
>>Uri
>
>Only some few more aspects in addition to Bob's answer ....
>
>If it is frequently used eg. with generated moves, i would say the extra memory
>references and instructions don't pay off. It may even be faster with a 16KByte
>4096-int-array.
I see that it is not very frequently used in generating moves.
It is used in my genout_of_check function but I think that I can replace it.
for example:
if (direction[square][target]<4) can be replaced by
if ((fil0(square)==fil0(target))||(rank0(square)==rank0(target)) because in the
releavant case it is a king move and I want to check if the king moves to rook
direction(note that I jave special array for kingmoves so I do a loop on all the
squares that the king maybe can goto:
when I generate king moves
my move generator starts with
for (k=0;k<kingnumber[square];k++)
{
target=kingmove[square][k];
>
>I often found arrays of packed structs favorably with such 64*64 arrays with low
>ranges (eg. distance, taxidistance, unique distance relationship (see links
>below) or direction).
I aam not sure if I understand
Do you say that you found an array as faster than using macros?
I use today abs and max to calculate Distance and I do not use 64*64 array.
Do you suggest that it is probably better to use arrays?
Uri
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