olofk
Only set a vlogdefine, do not assign a value to it
Goal: have fusesoc pass a define as "being set/defined" to a tool, do not assign a value to it.
Currently we have code like this:
parameters:
SYNTHESIS:
datatype: str
paramtype: vlogdefine
target:
lint:
parameters:
- SYNTHESIS=1
Switching SYNTHESIS=1 to SYNTHESIS will only make the vlogdefine available to the tool, but not set it. This is documented and intended behavior and generally makes sense.
For the "only define, don't assign a value" use case we need to extend the syntax a bit.
In the target section, I don't see a way to distinguish between "make vlogdefine available", "set vlogdefine without value", and "set vlogdefine to a given value".
I'd instead propose a new datatype define or isset or something like that (no good ideas come to mind right now). Assigning a truthy value (like 1 or true) to it would result in the define being set and passed to the EDA tool. Assigning a falsy value to it will not pass it to the EDA tool.
IIRC I experimented with this a while ago to have vlogdefine with datatype bool only define the var without assigning a value. The problem as I remember it was that some tools wouldn't let me set a define without a value. Might be possible to work around that, but I stopped investigating as I couldn't really find a valid use case for it. Do you actually need to have the define set without a value, or is it mainly for symmetry?
