[Iverilog-devel] The $min/$max$abs special functions (was Re: Snapshot and release plan)

[Stephen W. <st...@ic...>]

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Cary R. wrote:
| First I would like to see the full integration of the
| 1364-2005 math functions. Some of this is just using
| $clog2() as a template for the rest. The $min(), $max()
| and $abs() functions are a bit special in that they are
| effectively polymorphic. They support both a real result
| or if the input(s) are exclusively bit based a bit based
| result. We do not currently support a bit based result
| for any of these functions and even $clog2() is only an
| integer result. It is likely these three will need to be
| fully integrated into the VVP run time to support this.

I think it would be good to have the full-polymorphic behaviors
of $min(), $max() and $abs(). They are *not* defined by the
IEEE1364-2005 standard so they would be an extension. Obviously,
they should be enabled by the -gverilog-ams flag, but I think
it also makes sense to enable them with the -gicarus-misc flag.
(The icarus-misc generation flag is by default on.) Since they
start with "$", the name space pollution they cause is minor,
and by enabling them with -gicarus-misc, they can be turned
off by -gno-icarus-misc if even that bit is a problem.

And if it is easy to be better then the other guys, we should
certainly do it;-)

All the other math functions are part of 1364-2005 and should
be available to pure Verilog-2005 code. If they remain as
replaceable system functions, then we need not bother to disable
them for non-2005 generation settings.

- --
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
http://www.icarus.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."
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