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

Author: Matthias Gemuh

Date: 10:38:02 05/18/02


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.

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