R-value expressions are more general then L-value expressions, in that
the expression type may be a bit more complex. If the R-value expression
is part of an assignment, then elaborate with the constrained type from
the L-value. In other cases, where the expression type is not as obvious,
use expression type probes to figure out the type of the expression and
elaborate using that calculated type.
VHDL doesn't have a direct way to express "always @(posedge...)"
statements, but we do want to detect common paradigms that naturally
translate. This makes for a better translation.
Get to the point where our sample program parses completely, and
the sequential statements generate SequentialStmt objects and a
process object in the architecture.
Also add a few missing expression types.
Significant rework of scope management to unify the handling of
types in the ieee library and types/constants/components in packages.
This involved adjusting the parser rules to manage a stack of scopes
and rewriting the IEEE library support to not use global maps for
the loaded types.
Up till now only "global" use clauses were parsed
and as a result libraries were loaded.
Since use clauses can appear not only in global context,
parsing of non-global clauses has been introduced and
selected names are now handled (like name1.name2.name3).
These signals are declared in the architecture and are local to
the module. The Architecture already parsed and stored these signal
declarations, but this patch adds the ability to actually emit these
signals in the generated code.
In the process of doing this, I had to regularize the elaboration
and emit of VTypes, so that it can be used in multiple places, not
just in entity headers (for ports).
I also added support for bit selects of signals. This effected a couple
places in the parser, and expressions in general.
There are internal types that are unbounded arrays. Allow subtype
syntax that creates bounded versions of these arrays, and elaborate
them as vectors at port boundaries. This makes some interesting types
work out.
Also start replacing vhdlint and vhdlreal with int64_t and double,
which are reasonable values for universal_integer and universal_real
from the VHDL standard. I need these cleaned up because the ints in
particular are used for the literal expressions in array index constraints.
Elaboration will need a parse tree for expressions. Create one for
the expression types that are currently supported. Also add rules
and the keywords for all the remaining binary logical operators.
Stephen Williams
Pawel Szostek