ConcatSignal misbehavior converting to hdl #364

rafaelcorsi · 2022-03-29T16:37:02Z

On simulation ConcatSignal requires more than one argument 1 but it gives a error when converting to vhdl/verilog.

Not supported: extra positional arguments

System information

MyHDL Version: 0.11
Python Version: 3.10.2 (I also tested on python2)

Test Modules:

@block
def bar(a, y):
    @always_comb
    def comb():
        y.next = a

    return comb


@block
def foo(x, q, n=4):
    sig_x = [x(i) for i in range(n)]
    sig_q = [Signal(bool(0)) for i in range(n)]

    bar_list = [None for i in range(n)]
    for i in range(n):
        bar_list[i] = bar(sig_x[i], sig_q[i])

    @always_comb
    def comb():
        q.next = ConcatSignal(*reversed(sig_q))

    return instances()

Simulation works fine:

@block
def test_foo():
    x = Signal(intbv(0))
    q = Signal(intbv(0))

    foo_1 = foo(x, q)

    @instance
    def stimulus():
        x.next = 2
        yield delay(10)
        print(q)

    return foo_1, stimulus

Converting to vhdl gives an error

def convert_foo(hdl):
    x, q = [Signal(intbv(0)[15:0]) for i in range(2)]
    add_1 = foo(x, q)
    add_1.convert(hdl=hdl)

⚠️ Erro:

  File "/home/corsi/.local/lib/python3.10/site-packages/myhdl/conversion/_analyze.py", line 299, in visit_Call
    self.raiseError(node, _error.NotSupported, "extra positional arguments")
  File "/home/corsi/.local/lib/python3.10/site-packages/myhdl/conversion/_misc.py", line 148, in raiseError
    raise ConversionError(kind, msg, info)
myhdl.ConversionError: in file /home/corsi/work/ElementosBCC/MyHDL/z01/c-ula/modulos.py, line 48:
    Not supported: extra positional arguments

The text was updated successfully, but these errors were encountered:

rafaelcorsi · 2022-03-29T18:09:11Z

here is a implementation that works, is there a easy/ compact way to do this?

@block
def foo(x, q, n=4):
    sig_x = [x(i) for i in range(n)]
    sig_q = [Signal(bool(0)) for i in range(n)]

    bar_list = [None for i in range(n)]
    for i in range(n):
        bar_list[i] = bar(sig_x[i], sig_q[i])

    out_q = ConcatSignal(*reversed(sig_q))

    @always_comb
    def comb():
        q.next = out_q

    return instances()

josyb · 2022-07-30T10:17:28Z

You found out the right way to use ConcatSignal(). The simulation of the original description works fine as it simply creates a new ConcatSignal at every run of the @always_comb generator.
In theory one could expect that the convertor be able to handle it, but it is incompatible with the current flow of the conversion process. A possible option could be to expand concat() to handle a list of Signals; then you could write:

    @always_comb
    def comb():
        q.next = concat(*reversed(sig_q))

This enhancement is easy for simulation but hard to add to conversion :(

You can do without the sig_x list by using a ShadowSignal() in the call to bar

@block
def foo(x, q, n=4):
    sig_q = [Signal(bool(0)) for i in range(n)]

    bar_list = [None for i in range(n)]
    for i in range(n):
        bar_list[i] = bar(sig_x(i), sig_q[i])

    out_q = ConcatSignal(*reversed(sig_q))

    @always_comb
    def comb():
        q.next = out_q

    return instances()

rafaelcorsi added the bug label Mar 29, 2022

josyb removed the bug label Jul 30, 2022

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