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Logical NOT with MMX?
Am I missing something? I have just coded a RIPEMD160 Function in MMX only to just notice that there is no PNOT instruction.

This would make the next best way around this that I can think of: 


 AllSet QWORD 0ffffffffffffffffh



pnot MACRO mmX:REQ

   pxor mmX,AllSet

ENDM


Cheers! :)
Posted on 2002-07-02 23:05:44 by huh
Logical NOT with MMX?
Here is a lazy version without memory access:
pnot MACRO mmA:REQ, mmB:REQ

    pcmpeqd mmB,mmB ; set bits of scratch register

    pxor mmA,mmB ; reverse bits of destination

;   pandn mmA,mmB ; can replace pxor with this too

ENDM
The PANDN instruction allows you to optimize the NOT out of the algo, or maybe you could already have a register set (FF) - it is very useful to +/-1 or change sign of number.
Posted on 2002-07-03 07:03:34 by bitRAKE