Re: [vhdl-200x] Corrections to Minutes for VHDL-200X-FT meeting, San Jose Dec 4, 2003

Subject: Re: [vhdl-200x] Corrections to Minutes for VHDL-200X-FT meeting, San Jose Dec 4, 2003
From: Hamish Moffatt (hamish_moffatt@agilent.com)
Date: Tue Dec 16 2003 - 14:46:44 PST

Bailey, Stephen wrote:
> Active Low:
>
> if not we_n then
> ... -- Do write operation
> end if;

>
> Perhaps Andy has better examples that demonstrate his points?

I think this example demonstrates a good point: what test would COND
operator use on std_logic? Probably test for '1'. Thus the above is not
equivalent in the presence of metavalues;

    if not we_n then

is not the same as

    if we_n = '0' then

but really is

    if we_n /= '1' then

I think if you want boolean equivalence you are probably better to use
boolean types. Good synthesis and simulation tools will support them, so
why not?

Hamish 

-- 
Hamish Moffatt
R&D Engineer
Data Networks Division
Agilent Technologies
+61 3 9210 5782 (T210 5782) Tel

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