Fixes regression of simple_gen test.
Also extended ivl_lpm_size API call to support all LPM types. This
simplifies some of the VHDL LPM generation code a little.
This changes the implementation of $display/$write to use VHDL
report statements rather the the std.textio functions. The code
produced is simpler and more like what a real VHDL designed would
write. However it no longer exactly matches the Verilog output as
most VHDL simulators prepend the text with simulation time, entity
name, severity level, etc. There is a corresponding change in
ivtest to support this.
Conflicts:
tgt-vhdl/cast.cc
tgt-vhdl/display.cc
tgt-vhdl/vhdl_syntax.cc
tgt-vhdl/vhdl_target.h
Previous we generated a "wait for 0 ns" statement after
every blocking assignment that wasn't the last statement
in the process. While this implements the Verilog semantics,
it generates excessive waits, and cannot usually be synthesised.
This patch only generates "wait for 0 ns" statements when it
cannot be avoid (e.g. when the target of a blocking assignment
is read in the same process).
An example:
begin
x = 5;
if (x == 2)
y = 7;
end
Becomes:
x <= 5;
wait for 0 ns; -- Required to implement assignment semantics
if x = 2 then
y <= 7; -- No need for wait here, not read
-- wait for 0 ns (previously)
end if;
Conflicts:
tgt-vhdl/process.cc
tgt-vhdl/stmt.cc
tgt-vhdl/vhdl_target.h
This changes the implementation of $display/$write to use VHDL
report statements rather the the std.textio functions. The code
produced is simpler and more like what a real VHDL designed would
write. However it no longer exactly matches the Verilog output as
most VHDL simulators prepend the text with simulation time, entity
name, severity level, etc. There is a corresponding change in
ivtest to support this.
Previous we generated a "wait for 0 ns" statement after
every blocking assignment that wasn't the last statement
in the process. While this implements the Verilog semantics,
it generates excessive waits, and cannot usually be synthesised.
This patch only generates "wait for 0 ns" statements when it
cannot be avoid (e.g. when the target of a blocking assignment
is read in the same process).
An example:
begin
x = 5;
if (x == 2)
y = 7;
end
Becomes:
x <= 5;
wait for 0 ns; -- Required to implement assignment semantics
if x = 2 then
y <= 7; -- No need for wait here, not read
-- wait for 0 ns (previously)
end if;
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.
This avoids generating invalid VHDL signal names in the
following cases:
- The name begins or ends with an underscore
- The name contains two consecutive underscores
- The name is the same as a component declaration
- The name differs from another only in case
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).
This patch changes the output of VHDL unsigned bit strings
which are 4, 8, 16, 32, or 64 bits to use VHDL hex string
constants.
So the following:
"00000001"
Becomes
X"01"
Which is much easier to read
Previously the VHDL code generator managed memory for
the AST objects by requiring that each AST element be
responsible for deleting its children. The disadvantages
of this are that it's quite easy to accidentally leak
memory by forgetting to delete a child, and no AST pointers
may be shared by multiple parents (or we'd end up with
double-deletes) -- this results in unnecessary copies of
objects being made.
There's no real need for fine-grained memory management of
AST objects since once they're allocated they tend to
persist until the code generator is about to terminate, when
they should all be freed.
This patch provides a custom new/delete operator for
vhdl_element which logs the vhdl_element objects allocated
in a std::vector (after calling the default operator new).
Once the code generator is finished a single free_all_objects
call deletes all the AST objects in one go. The custom delete
operator is required so that we can still explicitly deallocate
vhdl_element objects before the code generator completes.
There are also some allocation statistics printed at the end
when -pdebug=1 is specified.
This patch generates VHDL sensitivity lists for sequential
as well as combinatorial processes which do not contain
a wait statement. Otherwise it falls back on the original
wait-on/until behaviour.
This should make the generated VHDL more acceptable to
synthesisers.
Finish cleaning up shadowed variables, flagged by turning on -Wshadow.
No intended change in functionality. Patch looks right, and is tested
to compile and run on my machine. No regressions in the test suite.
This is the end of the simple, coordination-free patches.
The remaining shadows are special cases that will need extra attention.
Specifying -pdepth=N only outputs entities that correspond
to Verilog modules found at depth < N in the hierarchy.
Setting -pdepth=0 (the default) outputs all entities.
This is for feature request 2391457
This patch optimises away straight line sequences like:
wait for 0 ns;
wait for X ns;
to:
wait for X ns;
This tidies up the output a bit.
It also has the effect of removing all code from initial
processes where the assignments have been extracted as
VHDL signal intialisers. (c.f. pr2391337)
A casex statement cannot be directly translated to a VHDL case
statement as VHDL does not treat the don't-care bit as special.
The solution here is to generate an if statement from the casex
which compares only the non-don't-care bit positions.
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 this was handled by creating an internal
signal that was connected to the output and could also
be read inside the entity. The correct solution is to
make the output `buffer' rather than `out'. However, this
does not work in the case when an output is connected to
an output of a child entity, and that values is read
in the parent. In this case *both* the outputs of the child
and the parent need to be made `buffer'.
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.
Cary R
Nick Gasson
Stephen Williams
Larry Doolittle