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Re: [f-cpu] Register Bank



hi, and thanks to Stéphane for the hints,

Michael Riepe wrote:
> 
> On Thu, Aug 02, 2001 at 10:09:11PM +0200, turlututu@bechamail.com wrote:
> [...]
> >       Some vendors (ST micro, IBM, Atmel, ...) seem to dislike
> > asynchronous resets in designs. They strongly prefer synchronous
> > resets. Resets are managed in a unique module but we have to modify
> > sequential processes; the original code is :
> [...]
> 
> >       Note that the use of a constant for the reset value is the best way
> > because you don\'t always know if the reset is active high or low before the
> > choice of a vendor.
> >       Do not forget that a majority of vendors do not support tri-states
> > ( \'Z\' ) in the core of a design, so we have to replace them with muxes.
> 
> This is only a case study, not the real code.
> 
> On the other hand, coding hints are welcome.  Thank you :)

it seems that we have found another code reviewer, cool ! :-P

> >       Could somebody tell me why there are
> > \"Write_0, Write_1, Write_Enable_0, Write_Enable_1\"
> > signals in the sensitivity list ?
> 
> Because some tools complain if they're not present.  I don't know why;
> as far as I understood, only Clk is needed in a sequential circuit with
> no asynchronous controls (which you just confirmed, somehow).

while we're at it, can you try to see what is necessary to have
"partial register write" ?
The current FC0 study requires the ability to write specifically
to the following : bits 0-7, 8-15, 16-31, 32-47, 48-63 (5 subfields).
the interface to the register set specifies 2x register
address (6 bits each) and 5 bits for each address, counting as
"write enable" for the subfields...


Concerning the register set reset, it can probably be performed
with some "tricks" : "hard" reset is probably not necessary.
i think that a "smart" use of the scheduler can trigger a burst
of register writes after a reset. what do you think ? :-)


>  Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
WHYGEE
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