[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: 6/8 bits imm instructions ( was Re: Rep:Re: [f-cpu] statistics of direct indexing usage)



On Fri, 10 Jan 2003 09:38:38 +0100 (CET)
devik <devik@cdi.cz> wrote:

> > > > like to use this particular combinaison?).
> > >
> > > uh uh, can you give me please some examples of such instruction ?
> >
> > It's the problème of bit 12-13 (manual 0.2.5).
> >
> > It's use in the scan instruction to bit-reverse the input or negate
> > it. It used as negate sign flag of the MAC instruction. All of this
> > flag can't be used in the 8 bits immediat of such fonction. So is a
> > pain or not ?
> 
> scan and mac doesn't use 12-13 (mac uses it for reg3) according
> manual 2.7. And why do you want to use immediates for scan !?
> 
> So that for me is still seems you are interested to have immediates
> for all insns (even for those where it makes no sense) and use
> 6 bits (register no) for it.
> 

yes, you get it.

> So I agree that it is possibly problem that 2 bits (8-6) can
> go into needed flag region.
> But still don't know what to do with it.
> Did you mean to use 6bit immediate for insns which have no
> room for 8bit imm and 8 bit for those whose have ?
> 

8 bit is better to have bigger number, but 6 bits is nicer because all
instructions could used. So it is a problem or not ?

> > orthogonal. But in other hand, 8 bit is fewer than 6 :)
> 
> he !? :)
> 
> devik
> 
> *************************************************************
> To unsubscribe, send an e-mail to majordomo@seul.org with
> unsubscribe f-cpu       in the body. http://f-cpu.seul.org/
> _____________________________________________________________________
> Envie de discuter en "live" avec vos amis ? Télécharger MSN Messenger
> http://www.ifrance.com/_reloc/m la 1ère messagerie instantanée de
> France
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/