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

Re: [f-cpu] Reamrks and suggestions about the manual



hi,

just a few remarks,

Michael Riepe wrote:
> On Sun, Jul 07, 2002 at 02:36:01PM +0200, Thomas Lavergne wrote:
> > Here's some remarks about the ISA decritpion in the manual, some are
> > little write error, other are remarks about coding of the ISA...
<snip>

as you have remarked : there are a lot of things to change.
But this manual is getting old and can be used as an historical
reference... the implementation has changed too quickly to
keep it acurate.

> [...]
> > At the top of the page you say 'logici.xxxx' so I understand this style
> > of codding 'logici.0111' like for the logic operand but ater you say
> > 'logici.s' like for bitop, we must clarify this and I think it was best
> > to have the same form for logic and logici even if we don't have all the
> > function of logic in logici.
> 
> The `logic[i].xxxx' instruction is obsolete. And it's rather hard to
> grok right because the function encoding is non-intuitive - e.g. does
> `logic.0010 A, B, C' mean `A and not B' or `B and not A'? Is `logic.0001'
> an AND or NOR operation? Both variants are possible, depending on the
> interpretation of the function field.

There is another problem : when one of the operands is negated
(ANDN and ORN), which one is it ?

currently, the VHDL source is the de facto reference and Cédric is
in charge of maintaining the manual, but it's a hard task.

WHYGEE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/