Re: IM201

Hi Russ,

> In pure simulation, users could run with full 4-state support. The IFLC
> process, however, would map "X" and "Z" types into some TBD 2-state
> representation (or, optionally, if an emulator implementation provided 4
> state, no mapping would be required).

I see two cases:

  1) Imported functions

  2) Exported functions/tasks

In case 1 no mapping is needed.  Either the emulator/simulator
supports 4-state and just passes them as is, or it only supports
2-state, but again, it can pass them as is; the user would just
never see values except 0 and 1.

In case 2 mapping would have to be done when the user is passing
X or Z to the HDL side if the target does not support 4-state.
Several choices present themselves here:

  1) Issue an error if X or Z is passed.

  2) Issue a warning and map X/Z.

  3) Silently map X/Z.

Platforms that do support X/Z would pass them unchanged of course.
As we talked about at the meeting there many opportunities for
incompatibilities between different implementations, and there
certainly enough rope for the user to shoot themselves in the foot,
as they say ;-)

Per

-- 
Per Bojsen                                Email: <bojsen@zaiqtech.com>
Zaiq Technologies, Inc.                   WWW:   http://www.zaiqtech.com
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