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Subject: Re: Begging for assembler FirstOne() and LastOne()

Author: Andrew Dados

Date: 10:52:57 05/18/02

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On May 18, 2002 at 13:38:02, Matthias Gemuh wrote:

>
>Hi Experts,
>I want to speed up my chess engine and need assembler versions of these
>functions. These below seem to be pentium-specific. I need something general
>and don't understand assembler.
>
>int FirstBit(BITBOARD a)
>{
>  __asm {
>        bsr     edx, dword ptr a+4
>        mov     eax, 31
>        jnz     l6
>        bsr     edx, dword ptr a
>        mov     eax, 63
>        jnz     l6
>        mov     edx, -1
>  l6:   sub     eax, edx
>  }
>}
>
>int LastBit(BITBOARD a)
>{
>  __asm {
>        bsf     edx, dword ptr a
>        mov     eax, 63
>        jnz     l7
>        bsf     edx, dword ptr a+4
>        mov     eax, 31
>        jnz     l7
>        mov     edx, -33
>  l7:   sub     eax, edx
>  }
>}
>
>Please, help me.
>
>Thanks,
>Matthias.

Those functions will work on all i386 - compatible processors. They are as
general as assembler can get.

-Andrew-

• Re: Begging for assembler FirstOne() and LastOne() Matthias Gemuh 12:48:52 05/18/02
  • Re: Begging for assembler FirstOne() and LastOne() Tim Foden 01:00:32 05/19/02
    • Re: Begging for assembler FirstOne() and LastOne() Matthias Gemuh 02:08:16 05/19/02

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