Minor fixes and code reorganization to remove a few more issues
that cppcheck is complaining about. It has a few false warnings
and some issues that need more investigation.
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).
Noticed this as part of the test case for pr2516774b. Under some
circumstances the input arguments would be cast to the wrong type.
This patch ensures that all the arguments have the correct type.
VHDL can't select bits from arbitrary expression so sometimes
translating IVL_EX_SELECT would fail. This is easily fixed by
replacing the select with a shift in this instance (and the
resizing)
The exponentiation operator in VHDL is not defined for numeric_std
types. We can get around this by converting the operands to integers,
performing the operation, then converting the result back to the
original type. This will work OK in simulation but certainly will not
synthesise unless the operands are constant.
However, even this does not work quite correctly. The Integer type in
VHDL is signed and usually only 32 bits, therefore any result larger
than this will overflow and raise an exception. I can't see a way
around this at the moment.
Previously only signedness was only corrected for the
result. This patch ensures the VHDL operands have the
same signedness as their Verilog counterparts.
This fixes a few of the signedX tests.
Mostly this ensures that a recursive call to a function
is made with the correct types (this may involve generating
code to cast expressions to the correct type).
Initial processes set a magic flag in the code generator
which allows it to push constant assignments into the
VHDL signal initialisation and omit the assignment.
However, it should only do this if the signal has not
already been read (otherwise the previous read would
not get the undefined value as expected)
Previously the code generator tried to infer the VHDL types. Now it
takes a much more dumb approach and forces the VHDL type to be
the same as the ivl type (derived from ivl_expr_signed and
ivl_expr_width) in the expression tree. This works much better :-)
Nick Gasson
Cary R