Re: [f-cpu] opcodes : missing m4

[jaap stolk <jwstolk@yahoo.com>]

--- Yann Guidon <whygee@f-cpu.org> wrote:
> hi !
  -- snip -
> not in the decoder : the decoder decodes, and Xbar
> transmits.
ok i put it in the xbar. :-)

> > can't stall the xbar, because we need to keep re-
> > loading the data in case there is a bypass.
> hmmmmmmmgrmblgrmbl.... did i miss something ?....
to keep it in hardware terms:( i won't say re-run the
xbar..)
the decoder may discover a (posible) bypass during
the stall, and change the input signals of the x-bar.
that will do the bypass.

> Don't you think it would be better to split eu_rop2
> to solve all these troubles ?
> For example, we remove the fanout/xbar stage
> and we let the Xbar function do the switches when
> the control signals are ok....

i think its more of a docoder (or xbar) task.
doing anything in a EU before there is any data
is a bit confusing.

> ok. do i remove the pipeline stage (with
> tmp_function)
> from eu_rop2_cycle() ? i believe that there should
> be no mention of "stalled" in the execution units
i agree.

the stalled signal is not strictly needed, in the EU.
the decoder is stalled, so it will re-provide the
ROP2_function. but it will save a lot of computation
(or bit changes) when we stop the ROP2_function
signal.




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