Author: Tim Foden
Date: 01:48:03 06/20/02
Go up one level in this thread
On June 18, 2002 at 13:14:28, Gerd Isenberg wrote: >On June 18, 2002 at 12:15:09, Adriano Bedeschi de Souza wrote: > >>Could someone help me with LSB (MSB) and POPCOUNT optimization? >> >>thx, >>Bedeschi > >some sample source code for msc6 with sone inline asm: > >LSB with reset found bit: > >// precondition: bb not null >__forceinline unsigned int BitSearchAndReset(BitBoard &bb) >{ >#ifdef _M_IX86 > __asm > { > mov edx, [bb] > bsf eax, [edx+4] > xor eax, 32 > bsf eax, [edx] > btr [edx],eax > } I'm afriad the above code won't work as intended, as the "btr [edx], eax" line will always affect the low 32 bits and never the high 32 bits. Cheers, Tim.
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