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.
The Cygwin compiler is a bit picky. This patch adds some casts
to remove compilation warnings. In the past I have had warnings
off because of problems with the STL, but we may as well get
rid of the warnings we can. It also does not recognize that an
assert(0) or assert(false) ends a routine so it complains about
no return at end of function or variables not being defined.
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
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.
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
This patch is a fix for pr2516774.
The idea is to generate a local variable inside
a function whenever an argument is assigned to. The
variable has an initial value of the argument value
and is used in its place for the remainder of the
function. This patch also handles the case where the
argument is assigned to inside a while loop.
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.
This patch generates a sensitivity list for combinatorial
VHDL processes if they don't contain a wait statement, and
a wait-on statement if they do contain another wait statement.
This should help synthesisers correctly identifier
level-sensitive latches.
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)
This changes the assignment statement generator so that
each VHDL declaration "knows" which type of assignment
statement can/should be used on (i.e. signals must be
assigned with <=). This will help us catch cases when
we try to use, for example, := with signals. This occurs
in pr2362211 where we try to assign to a signal within
a function (where only := can be used).
With this small patch, building succeeds with Debian's current gcc-snapshot,
gcc (Debian 20081130-1) 4.4.0 20081130 (experimental) [trunk revision 142292]
That gcc also warns about the remaining #idents in
vvp/concat.cc
vvp/dff.h
The resulting build shows some regressions in the test suite, that
I am still investigating. The patch does not break building, or show
test suite regressions, with gcc-4.3.
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.
Emitting a VHDL expression like Resize("01", 32) is ambiguous
between interpreting "01" as a Signed or an Unsigned. There's
no point actually outputting this as we can sign-extend the
constant value in the code generator, which is what this
patch does.
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.
This splits up the monolithic and confusing vhdl_expr::cast function into
several smaller to_XXX functions which each generate code to cast an
expression to type XXX. This makes it much easier to understand and maintain.
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'.
Christian Taedcke
Cary R
Nick Gasson
Stephen Williams
Larry Doolittle