Author: Simon Waters
Date: 11:56:02 10/30/00
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On October 28, 2000 at 22:01:27, Robert Hyatt wrote: > >Crafty still has C code for these, although they are replaced by asm modules >on the X86 machines... > >if you look in "boolean.c" you will find the way I do these things... Thanks - I found the assembler routines and stopped looking. I'd actually changed gnuchess to use the same algorithmn for PopCnt as Crafty before looking at the assembler - based on the excellent bitwtiddling paper from RICE - although it doesn't seem to have any performance benefit over the algorithmns you've already donated to gnuchess (At least I seem to have gained about 9% but can't be sure where it is coming from - my poor linux box was floating around run level 2 trying to produce some more consistent numbers). For leading bit I switched to the ffs builtin to gcc. These two changes take the routines nbits and leadz out of the leading positions when I profile without optimisation - which hints that they have helped - but I'm having trouble proving it when we get to -O3. Che Sera Sera.
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