Subject: Re: [sv-cc] DirectC C Layer - encoding of x/z
From: Andrzej Litwiniuk (Andrzej.Litwiniuk@synopsys.com)
Date: Tue Feb 04 2003 - 16:05:33 PST
> > /* canonical representation */
> >
> > #define sv_0 0
> > #define sv_1 1
> > #define sv_z 2 /* representation of 4-st scalar z */
> > #define sv_x 3 /* representation of 4-st scalar x */
KEVIN:
> Value, strength and certainty are orthogonal, this would be better as:
>
> #define sv_0 0
> #define sv_1 1
> #define sv_z 2 /* representation of 4-st scalar z */
> #define sv_x 4 /* representation of 4-st scalar x */
>
> - this is relevent if you are bridging into a mixed-signal/analog environment.
The proposed representation of x and z is consistent with Verilog 1364-1995
standard, see LRM p. 340:
aval bval value
---------------------
0 0 0
1 0 1
0 1 z
1 1 x
I assumed that numerical representation is calculated as {bval,aval}.
BTW, I prefer VCS notation with "c" and "d" fields, cf. svLogicVec32,
because it seems more intuitive: "c" stands for "control" and "d" stands for
"data".
Andrzej
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