Tydi TODO

[jvanstraten]

The following things have come up that are either broken or aren't very nice about the current specification.

• Asynchronous signals cannot be reversed (Non-stream signal reversibility #23). Proposed solutions:
  • Make reversal part of fields instead of Stream nodes. (This is problematic because at best it introduces implicit streams again. It also means tools cannot reasonably place registers/clock domain crossings automatically.)
  • Remove the signals from the specification, but add a separate type system (based on Tydi, bit supporting reversal) for user-defined signals.
  • Keep the current specification for signals that tools may insert registers into, but add a separate type system (based on Tydi) for user-defined signals that supports reversal that the tools don't do anything with.
• Order of asynchronous signals and streams is not maintained.
• The user-friendly representation notes should be removed. This and any requirements on field names beside uniqueness are entirely in user control. Code generators are considered to be users in this context; this means that generators may impose additional constraints.
• Add a flag to Stream nodes and to physical streams that specifies whether empty sequences are supported or not.
• Maybe add a note that Tuple(N, T) may be used as a shorthand for Group(0: T, 1: T, ..., N-1: T).