Adds support for negative edge-triggered Sequentials. In some cases, downstream tools may treat an inverted clock fed into a sequential differently than a negative edge triggered sequential. Functionally, in simulation, the behavior is the same for either option. Generators may choose to generate these differently (e.g. using negedge vs. posedge in SystemVerilog generation).
Additionally fixed a bug where a multi-triggered Sequential may not generate X's if one trigger is valid and another (later specified) trigger is invalid.
The changes also motivated some refactoring of trigger handling in Sequential, as well as renaming of the first positional argument in Sequential.multi.
Related Issue(s)
This is related to the discussion on #42, where previously it was decided not to include negedge due to lack of motivation. Downstream tool differences now motivate adding the feature.
Testing
Added new tests, existing tests pass.
Backwards-compatibility
Is this a breaking change that will not be backwards-compatible? If yes, how so?
No, but the signature of Sequential.multi has been slightly expanded and modified:
first positional argument changed name from clks to posedgeTriggers
added negedgeTriggers as a named optional argument
Documentation
Does the change require any updates to documentation? If so, where? Are they included?
This is a relatively uncommon feature, so documentation added onto the API docs should be sufficient (extra example in user guide not really needed).
Description & Motivation
Adds support for negative edge-triggered
Sequentials. In some cases, downstream tools may treat an inverted clock fed into a sequential differently than a negative edge triggered sequential. Functionally, in simulation, the behavior is the same for either option. Generators may choose to generate these differently (e.g. usingnegedgevs.posedgein SystemVerilog generation).Additionally fixed a bug where a multi-triggered
Sequentialmay not generate X's if one trigger is valid and another (later specified) trigger is invalid.The changes also motivated some refactoring of trigger handling in
Sequential, as well as renaming of the first positional argument inSequential.multi.Related Issue(s)
This is related to the discussion on #42, where previously it was decided not to include
negedgedue to lack of motivation. Downstream tool differences now motivate adding the feature.Testing
Added new tests, existing tests pass.
Backwards-compatibility
No, but the signature of
Sequential.multihas been slightly expanded and modified:clkstoposedgeTriggersnegedgeTriggersas a named optional argumentDocumentation
This is a relatively uncommon feature, so documentation added onto the API docs should be sufficient (extra example in user guide not really needed).