Author: Dan Newman
Date: 02:32:15 12/09/98
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On December 06, 1998 at 10:23:54, Robert Hyatt wrote:
>I haven't finished this yet... I've sent it to a couple of people in draft
>form when they asked... And will do the same for you if you are interested.
>Note that it is a rough draft, reasonably complete, but not "polished" yet...
I'd be interested in a copy too (hope you're not too inundated with
requests). email: dnewman@bellatlantic.net
After reading the lastest posts on bitboards, I've begun trying my
hand at them (again). The main sticking point with me was the cost
of bit index extraction--I was only able to get bitboard move
generation to go at about half the speed of 0x88. But, I just did
an experiment with the BSF instruction (inline assembly) and have
gotten the best results yet--something less than 9 clocks per
bit-index on a P6. My previous best was 16 clocks using pure C.
One trick I just discovered (which is pretty obvious actually) is
using XOR to clear the bit: I had been doing this:
bitboard &= ~(1 << index);
but this can be done, saving one operation, like this:
bitboard ^= (1 << index);
since we know the bit is set.
-Dan.
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