Newer versions of GHDL seem to be stricter when checking this than
older versions. ModelSim still accepts an incomplete with-select,
however.
This patch makes the output 'U' if none of the conditions match.
I forgot to modify the LPM generating code with the
last patch. This *should* now always ensure a signal
is readable before code is generated to read from it.
This patch corrects several bugs with the generation of
VHDL `buffer' ports. The code generator should now
generate a buffer only if the port needs to be read inside
the architecture, otherwise it will stay `out'.
This also correct a bug where an output port is connected
directly to the output of an instantiated component. Generating
`buffer's would work here, but a more idiomatic VHDL approach is
to declare an intermediate signal which both outputs are connected
to. This is implemented in the patch (fixes the regression of
readout.v in the testsuite).
Combinatorial UDPs will be implemented with a `with ... select'
statemetnt. However the input to this must be "locally static".
This patch joins the inputs into a vector which can be used as
the select expression.