I originally picked :pc: as it is short for "python code", but it is
obscure and :py: is not taken, so a much more obvious role can be used
instead. Also, we all typo :pc: as :py: all the time anyway.
In this environment it's not feasible, or at least it's not documented
how, to distribute JavaScript code by packaging it as a wheel; only
Wasm code (as shared objects) can be distributed this way. The current
`amaranth-yosys` strategy would not work even though wheels can be
installed on Pyodide, and Yosys will need to be explicitly provided by
the environment instead.
The implementation is sufficiently generic that non-Pyodide hosts could
potentially make use of it, though it doesn't seem like any exist at
the moment.
In some environments (e.g. Pyodide) it may be advantageous to not load
this library, and with the import at file level, it makes the entire
simulator unusable, not just `PySimEngine.write_vcd`.
This might also help people whose Python environments are unusually
broken, whom we've historically accommodated.
The new intermediate representation will enable global analyses
on Amaranth code without lowering it to another representation
such as RTLIL.
This commit also changes the RTLIL builder to use the new IR.
Co-authored-by: Wanda <wanda@phinode.net>
The source location is set to the place where `In`/`Out` was created.
The source location of the instantiation is tracked but overwritten;
we will need to change the internal structure storing those to be able
to include both.
Fixes#1085.
This closes#721 by implementing get_async_ff_sync() using FDPE
primitives to obtain exactly the netlist that we want. This consits
of a chain of N FPDEs (by default N = 2) with all their PRE pins
connected to the reset for a positive edge reset or to the ~reset
for a negative edge reset. The D pin of the first FDPE in the chain
is connected to GND.
To make timing analysis work correctly, two new attributes are
introduced: amaranth.vivado.false_path_pre and
amaranth.vivado.max_delay_pre. These work similarly to
amaranth.vivado.false_path and amaranth.vivado.max_delay, but affect
only the PRE pin, which is what is needed for this synchronizer.
The TCL has been modified to generate constraints using these
attributes, and there are comments explaining how to use the attributes
directly in an XDC file in case the user wants to manage their XDC
file manually instead of using the TCL.
