Author: Bas Hamstra
Date: 12:33:39 04/24/01
Go up one level in this thread
On April 23, 2001 at 19:30:20, Alex Boby wrote:
>
>I used to have this:
>
>------------
>void parseBitboard (int from, struct MoveList *ml, bitboard attack)
> {
> int i;
>
> for (i=0; i<64; i++)
> {
> if (attack&mask[i])
> [add move to list]
> }
> }
>------------
>and got this in the profile:
>7301.351 3.9 37127.739 19.6 538488 _parseBitboard (pierre.obj)
>
>and then, figuring I would get a significant speed increase, I switched to this:
>
>-----------------
>int findBitIndex(bitboard data)
> {
> int index;
>
> __asm
> {
> bsr edx, dword ptr data+4
> mov eax, 32
> jnz s1
> bsr edx, dword ptr data
> mov eax, 0
> jnz s1
> mov edx, -1
> s1: add edx, eax
> mov index, edx
> }
>
> return index;
> }
>
>void parseBitboard (int from, struct MoveList *ml, bitboard attack)
> {
> int index;
>
> while ((index = findBitIndex(attack))!=-1)
> {
> [add move to list]
> attack -= mask[index];
> }
> }
>-------------
>and then got this in the profile:
> 6763.331 4.4 32424.707 21.1 530420 _parseBitboard (pierre.obj)
> 1313.554 0.9 1313.554 0.9 3523746 _findBitIndex (pierre.obj)
>
>with about a 10% drop in nodes/sec.
>
>I thought that BSF & BSR were supposed to be fast! What am I doing wrong?
>This is on an Intel P3/500 w/ win2k.
I use:
int LastOne(BB M)
{ __asm
{ mov EAX, dword ptr [M]
bsf EAX, EAX
jnz Done
mov EAX, dword ptr [M+4]
bsf EAX, EAX
add EAX, 32
Done:
}
}
That saves one jump. Also, VC inlines the assembly flawlessly, while Borland
does NOT inline asm. IE in Borland when you use "inline LastOne()" it ignores
it. I am curious if the other routines posted are faster.
Best regards,
Bas.
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