Re: [Iverilog-devel] Real constants in compiler output.

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

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Cary R. wrote:
> While working on pr1869769 (real comparisons in cont. assign.) I have run
> into a number of slightly related problems. The major one I have left is
> that real constants Cr<xxx> are not handled very well. The code generator
> prints them with a plain %lg which limits the precision of the value
> passed to the run time. Is there a system agnostic way to find the maximum
> precision so we can pass that to %g?

Better would be to use the same sign-mantissa-exponent form as
is generated for the %loadi/wr instruction to get a real value.
This format is also clearly documented, along with ways to carry
the various zeros, infinities and NaNs.

> The other half of the problem is that when the real number prints with an
> exponent the runtime crashes. This is because a '+' is not considered a
> valid character in a Cr<xxx> constant and after fixing that it complains
> about an invalid name which I am assuming is the '+' again. Should I just
> add '+' as need to fix things or should I submit this as a separate bug
> report for a more thorough analysis?

This is an issue in the lexor. I started creating an IDENTIFIER
rule in the lexor.lex that is specially for matching Cr<...> and
its internal complexities. Just fix that.

- --
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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