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Subject: Re: Bitboard question

Author: Andrew Dados

Date: 14:58:06 12/03/98

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On December 03, 1998 at 13:34:31, Inmann Werner wrote:

>Thanks a lot Robert and Peter!
>
>It is what I need, and i am on the right path.
>
>But-
>are prozessors really as silly, not to have a simple code (in the prozessor)
>doing the bit testing?
>
>Werner

   All 32-bit Intel processors (and compatibles) since 386 have BSF/BSR
instructions made just this sort of bit testing/setting/resetting. For example
this assembler sequence:

mov ecx,32
bsf eax,ecx
jz @@nobits

will give you number of first set bit in eax (5 in this case). Zero flag will be
set if no set bits
were present. BSR additionally resets first found bit.

  Andrew



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