Author: Sune Fischer
Date: 13:15:51 12/05/03
Go up one level in this thread
On December 05, 2003 at 13:43:05, Russell Reagan wrote:
>On December 05, 2003 at 07:20:37, Gerd Isenberg wrote:
>
>>Was it your intention to mix lsb- with msb-routines?
>
>For this program they produce the same checksum since all of the bitboards have
>a population of one (msb == lsb, in this test).
>
>It probably doesn't matter for a lot of bitboard chess programs. For most, any
>bit will do. For some it matters. I know for some of the filler stuff I've
>written I had to make sure I used a lsb or msb. I think both will be
>approximately the same speed, or very close.
You can optimize some of the routines to take advantage of that.
For instance you save the &'s in the TableBitscan16 version:
int TableOneBitscan16 (Bitboard b) {
if (b<<48)
return table16[b];
if (b<<32)
return table16[b >> 16] + 16;
if (b<<16)
return table16[b >> 32] + 32;
return table16[b >> 48] + 48;
}
-S.
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