Fsub

From: '\\\\o//'annabee ('\\o//'annabee)
Date: 03/08/05 

Date: Tue, 08 Mar 2005 12:16:27 +0100

Hello.

Do anyone know what is the diffrence between

fld D§ebx + D3DVector.z
fld D§eax + D3DVector.z
fsubrp ST0 ST1

and

fld D§eax + D3DVector.z
fld D§ebx + D3DVector.z
fsubp ST0 ST1

The result is the same, but is one better than the other ?

What would be even better way ? Maybe this ?

fld D§eax + D3DVector.x
fsub D§ebx + D3DVector.y

My test seem to indicate that this is slower:
     fld D§eax + D3DVector.x
     fsub D§ebx + D3DVector.y

And that this is slighly faster, and the same as the subp one
     fld D§ebx + D3DVector.y
     fld D§eax + D3DVector.y
     fsubrp ST0 ST1

I am wondering how do do the fastest subtract of two floats (4 bytes /
singles)
Is it in anyway possible to setup the hardware to subtract all components
of the
vector at once ? 

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