Re: [fpu] FPU operations

[Jamil Khatib <jamilkhatib75@yahoo.com>]

--- Damjan Lampret <damjanlampret@yahoo.com> wrote:
> > > - SF compare
> > compare for equality only?
> > 
> Depends. You want one insn that will set status bits
> (eq, lt, gt) or do
> you want separate compare instructions. GCC really
> doesn't care.
> 

So it is OK to have one instruction for all three
operations, but what about all status and control
registers? I'll put all of them internallay in the FPU
but we need to define a method to access them

FPU Internal registers are:
1) compare result 
2) Rounding mode
3) Exception flags
4) Exception masks

> > 
> > If we are going to define MAC we should have a
> > seperate block for it
> 
> Why? With one block for Mul and the other for Add
> you get MAC if they
> work as a pipeline (though you need accumulator
> register)

Yes this will do the operation but it will not give
any speed up. Usally MAC operations are used to
produce speed up over the two stage mul-add


Regards
Jamil Khatib


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