Re: [fpu] Architecture

["Damjan Lampret" <damjan.lampret@arnes.si>]

>
> Thats fine but do you have to modify the existing datapath controller to
handel
> the FPU?

For single precision no. For double you need register file with 64-bit
registers and you still don't need to modify datapath controller. But if you
want to combine to 32-bit registers to get one 64-bit FP operand then one
needs to modify datapath controller since register file will need 4 read
ports.

>
> So what do you suggest to support 80-bit data "it should be the same as
128"
> according to OR1K architecture. can we add special rergister file only for
FPU
> that has 80 bit width?

Do we really need 80 and 128 bit precision? I guess at least for a start
single and double precision would be enough. In fact I would put in our
first silicon test run (hopefully this will happen at the end of summer)
only single precision FPU since I think it is important to have small die
(at least for the first silicon). Idea is to be able to "sell" this first
implementation chips for a price of a hamburger. ;-)

regards, Damjan