LogicNets, inOuts, and TriStateBuffer (support for bidirectional wires)

[mkorbel1]

Description & Motivation

Support for bidirectional wires (LogicNets) and in-out ports (inOuts).

• Added LogicNet
• Added inOut ports to Module
• Added TriStateBuffer
• Deprecated CustomSytemVerilog and replaced with similar but more flexible APIs for SystemVerilog. BREAKING: This also impacted InlineSystemVerilog and ExternalSystemVerilogModule, whose APIs have changed.
• Improved naming of intermediate, structure, and array signals in various places to make debug easier.
• BREAKING: increased minimum Dart SDK to 3.0.0
• BREAKING: updated Interface.connectIO API for inOutTags
• Fixed a bug where expressionlessInputs may not have been honored in non-inline custom SystemVerilog modules.
• Fixed a bug where in some cases an xor between two LogicValues could cause an exception due to a false width mismatch.
• Added better checking, error handling, and message when module hierarchy cannot be properly resolved (e.g. self-containing modules, modules within multiple hierarchies).
• Breaking: Updated APIs for Synthesizer.synthesize and down the stack to use a Function to calculate the instance type of a module instead of a Map look-up table.
• Added srcConnections API to Logic to make it easier to trace drivers of subtypes of Logic which contain multiple drivers.

Related Issue(s)

Fix #8
Fix #476
Fix #477

Testing

Extensive new tests added for new features and bug fixes.

Backwards-compatibility

Is this a breaking change that will not be backwards-compatible? If yes, how so?

Yes!

• Breaking: ExternalSystemVerilogModule and InlineSystemVerilog now extend SystemVerilog instead of CustomSystemVerilog, meaning the instantiationVerilog API arguments have been modified.
• Breaking: Increased minimum Dart SDK version to 3.0.0.
• Breaking: Interface.connectIO has an additional optional named argument for inOutTags. Implementations of Interface which override connectIO will need to be updated.
• Breaking: Updated APIs for Synthesizer.synthesize and down the stack to use a Function to calculate the instance type of a module instead of a Map look-up table.

Documentation

Does the change require any updates to documentation? If so, where? Are they included?

Yes! Added to and updated user guide