Author: Dann Corbit
Date: 12:07:56 02/23/06
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On February 23, 2006 at 15:02:25, Christopher Conkie wrote: >On February 23, 2006 at 14:49:01, Dann Corbit wrote: > >>On February 23, 2006 at 14:47:23, Christopher Conkie wrote: >> >>>Is there a way to keep board representations entirely in hexadecimal format >>>until output of moves are required. How would one accomplish rotation for >>>diagonals without conversion. For example, is it needed to convert pieces to a >>>number if you started with something like..... >>> >>>typedef unsigned long long bitboard; >>> >>>bitboard B_Occ = 0xffff000000000000ULL; >>>bitboard W_Occ = 0x000000000000ffffULL; >>> >>>bitboard All_P = 0x00ff00000000ff00ULL; >>>bitboard All_N = 0x4200000000000042ULL; >>>bitboard All_B = 0x2400000000000024ULL; >>>bitboard All_R = 0x8100000000000081ULL; >>>bitboard All_Q = 0x1000000000000010ULL; >>>bitboard All_K = 0x0800000000000008ULL; >>> >>>I have been toying with this idea but am not quite sure of the validity of it's >>>basis. I was thinking that if less conversion took place it would improve speed >>>significantly. >>> >>>Any thoughts would be nice. >> >>Internally, all the numbers are binary. If you assign them a decimal number, it >>gets converted to binary internal format. It happens at compile time and so the >>speed difference is 0.00000% >> >>Or maybe you are joking and left out the smiley. > >Yes and no. ;-) > >Seriously I am looking at ways to improve speed without having to use arrays to >rotate for diagonals. > >There is a max of 7 squares in any one specific horizontal, vertical or diagonal >direction for a piece to move to. If we know that, why not have a table that >looks at each of the 8 directions and subsequent squares in turn until a >friendly or opposing piece is found and deal with that accordingly. This would >require a table that is stepped through consisting of the 56 values that shift >up, down or across. > >Did I explain that well enough. It is a bit bitty I know..... > >It just seems to me simpler to me to comprehend. Question is would it be >significantly slower or maybe even faster? > >:-) > >Christopher OK, now I see what you were after. Actually, I have done something very similar to your idea. You can write a program to write a program. What the program does is to examine all (max of 128) possible bit combinations for a slider on a given square. Then the result is a giant switch statement with integral constants. This idea is a good one and the results are very fast. You can output not only the captures and non-captures, but also the pins and half-pins as bit masks. You can also know which of your own chessmen is defended and by what piece types they are defended. All of this can be put into a precomputed data structure.
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