This also changes `decoder` a bit: when an enum is used as a decoder,
it is converted to a `Format.Enum` instead. The original enum is still
stored on the `decoder` attribute, so that it can be propagated
on `Signal.like`.
This includes a few minor code changes:
- Removing redundant `lib.memory.Memory.Init = hdl.MemoryData.Init`
re-export;
- Renaming `FrozenError` to `FrozenMemory` and moving it to `.hdl`;
- Marking `ReadPort` and `WritePort` as `@final`.
This check was originally added out of abundance of caution, but since
then it was observed that reset-less-ness is purely an implementation
detail (see #1220), and furthermore it interferes with adaptation of
`FIFOInterface`` signals (where `[rw]_data` are reset-less) for RFC 61.
These accessors used to be necessary (in addition to `.shape()`) while
the AST nodes were mutable. However, after commit 2bf1b4da that made
AST nodes immutable, there is no technical requirement to keep them
around. Additionally:
- `len(value)` is shorter than `value.width` and works with any `value`
- `value.shape().signed` is longer than `value.signed` but works with
any `value`
* Given a private name `$\d+` in RTLIL (as they are not named in the IR)
* Not automatically added to VCD files (as they are not named in the IR)
* Cannot be traced to a VCD (as they have no name to put in the file)
* Cannot be used with an unnamed top-level port (as there is no name)
If delta cycles are expanded (i.e. if the `fs_per_delta` argument to
`Simulator.write_vcd` is not zero), then create a string typed variable
for each testbench in the simulation, which reflects the current
command being executed by that testbench. To make all commands visible,
insert a (visual) delta cycle after each executed command, and ensure
that there is a change/crossing point in the waveform display each time
a command is executed, even if several identical ones in a row.
If delta cycles are not expanded, the behavior is unchanged.
