Arrange for ports used as l-values to be declared as "reg".

Entity output ports may be used as l-values in a process within
the bound architecture. Detect that case during elaboration and
adjust the signal declaration so that it works in the Verilog pass.

vhdlpp/Makefile.in

@@ -59,8 +59,10 @@ LIBS = @LIBS@ @EXTRALIBS@
 
 M = StringHeap.o LineInfo.o
 
-O = main.o architec.o architec_elaborate.o compiler.o entity.o entity_elaborate.o \
-    expression.o package.o scope.o sequential.o vsignal.o vtype.o vtype_elaborate.o \
+O = main.o architec.o compiler.o entity.o \
+    expression.o package.o scope.o sequential.o vsignal.o vtype.o \
+    architec_elaborate.o entity_elaborate.o expression_elaborate.o \
+    sequential_elaborate.o vtype_elaborate.o \
     lexor.o lexor_keyword.o parse.o \
     parse_misc.o library.o vhdlreal.o vhdlint.o \
     architec_emit.o entity_emit.o expression_emit.o sequential_emit.o vtype_emit.o \

vhdlpp/architec_elaborate.cc

@@ -20,6 +20,7 @@
 # include  "architec.h"
 # include  "entity.h"
 # include  "expression.h"
+# include  "sequential.h"
 # include  <typeinfo>
 # include  <cassert>
 
@@ -45,7 +46,7 @@ int ComponentInstantiation::elaborate(Entity*ent, Architecture*arc)
 {
       int errors = 0;
 
-      const ComponentBase*base = arc->find_component(cname_);
+      ComponentBase*base = arc->find_component(cname_);
       if (base == 0) {
 	    cerr << get_fileline() << ": error: No component declaration"
 		 << " for instance " << iname_
@@ -71,5 +72,12 @@ int ComponentInstantiation::elaborate(Entity*ent, Architecture*arc)
 
 int ProcessStatement::elaborate(Entity*ent, Architecture*arc)
 {
-      return 0;
+      int errors = 0;
+
+      for (list<SequentialStmt*>::iterator cur = statements_list_.begin()
+		 ; cur != statements_list_.end() ; ++cur) {
+	    errors += (*cur)->elaborate(ent, arc);
+      }
+
+      return errors;
 }

vhdlpp/entity.cc

@@ -20,6 +20,7 @@
 
 # include  "entity.h"
 # include  "architec.h"
+# include  <cassert>
 
 using namespace std;
 
@@ -69,3 +70,10 @@ Architecture* Entity::add_architecture(Architecture*that)
 
       return arch_[that->get_name()] = that;
 }
+
+void Entity::set_declaration_l_value(perm_string nam, bool flag)
+{
+      map<perm_string,VType::decl_t>::iterator cur = declarations_.find(nam);
+      assert(cur != declarations_.end());
+      cur->second.reg_flag = flag;
+}

vhdlpp/entity.h

@@ -33,6 +33,8 @@ class Architecture;
 
 class InterfacePort : public LineInfo {
     public:
+      InterfacePort() { mode = PORT_NONE; type=0; }
+
 	// Port direction from the source code.
       port_mode_t mode;
 	// Name of the port from the source code
@@ -92,7 +94,17 @@ class Entity : public ComponentBase {
 	// returned pointer is the same as the passed pointer.
       Architecture* add_architecture(Architecture*);
 
+	// After the architecture is bound, elaboration calls this
+	// method to elaborate this entity. This method arranges for
+	// elaboration to hapen all the way through the architecture
+	// that is bound to this entity.
       int elaborate();
+
+	// During elaboration, it may be discovered that a port is
+	// used as an l-value in an assignment. This method tweaks the
+	// declaration to allow for that case.
+      void set_declaration_l_value(perm_string by_name, bool flag);
+
       int emit(ostream&out);
 
       void dump(ostream&out, int indent = 0) const;

vhdlpp/entity_emit.cc

@@ -69,6 +69,8 @@ int Entity::emit(ostream&out)
 			break;
 		      case PORT_OUT:
 			out << "output ";
+			if (decl.reg_flag)
+			      out << "reg ";
 			if (decl.msb != decl.lsb)
 			      out << "[" << decl.msb
 				  << ":" << decl.lsb << "] ";

vhdlpp/expression.h

@@ -40,6 +40,13 @@ class Expression : public LineInfo {
       Expression();
       virtual ~Expression() =0;
 
+	// This virtual method handles the special case of elaborating
+	// an expression that is the l-value of a sequential variable
+	// assignment. This generates an error for most cases, but
+	// expressions that are valid l-values return 0 and set any
+	// flags needed to indicate their status as writable variables.
+      virtual int elaborate_lval(Entity*ent, Architecture*arc);
+
 	// The emit virtual method is called by architecture emit to
 	// output the generated code for the expression. The derived
 	// class fills in the details of what exactly happened.
@@ -196,6 +203,7 @@ class ExpName : public Expression {
       ~ExpName();
 
     public: // Base methods
+      int elaborate_lval(Entity*ent, Architecture*arc);
       int emit(ostream&out, Entity*ent, Architecture*arc);
       bool is_primary(void) const;
       bool evaluate(ScopeBase*scope, int64_t&val) const;
@@ -213,6 +221,7 @@ class ExpNameALL : public ExpName {
       ExpNameALL() : ExpName(perm_string()) { }
 
     public:
+      int elaborate_lval(Entity*ent, Architecture*arc);
       void dump(ostream&out, int indent =0) const;
 };
 

vhdlpp/expression_elaborate.cc

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2011 Stephen Williams (steve@icarus.com)
+ *
+ *    This source code is free software; you can redistribute it
+ *    and/or modify it in source code form under the terms of the GNU
+ *    General Public License as published by the Free Software
+ *    Foundation; either version 2 of the License, or (at your option)
+ *    any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *    Picture Elements, Inc., 777 Panoramic Way, Berkeley, CA 94704.
+ */
+
+# include  "expression.h"
+# include  "architec.h"
+# include  "entity.h"
+# include  <iostream>
+
+using namespace std;
+
+int Expression::elaborate_lval(Entity*, Architecture*)
+{
+      cerr << get_fileline() << ": error: Expression is not a valie l-value." << endl;
+      return 1;
+}
+
+int ExpName::elaborate_lval(Entity*ent, Architecture*arc)
+{
+      int errors = 0;
+
+      if (const InterfacePort*cur = ent->find_port(name_)) {
+	    if (cur->mode != PORT_OUT) {
+		  cerr << get_fileline() << ": error: Assignment to "
+			"input port " << name_ << "." << endl;
+		  return errors += 1;
+	    }
+
+	    ent->set_declaration_l_value(name_, true);
+	    return errors;
+      }
+
+      Signal*sig = arc->find_signal(name_);
+      if (sig == 0) {
+	    cerr << get_fileline() << ": error: Signal/variable " << name_
+		 << " not found in this context." << endl;
+	    return errors + 1;
+      }
+
+      return errors;
+}
+
+int ExpNameALL::elaborate_lval(Entity*ent, Architecture*arc)
+{
+      return Expression::elaborate_lval(ent, arc);
+}

vhdlpp/scope.cc

@@ -93,3 +93,12 @@ ComponentBase* Scope::find_component(perm_string by_name)
       else
 	    return cur->second;
 }
+
+Signal* Scope::find_signal(perm_string by_name)
+{
+      map<perm_string,Signal*>::const_iterator cur = signals_.find(by_name);
+      if (cur == signals_.end())
+	    return 0;
+      else
+	    return cur->second;
+}

vhdlpp/scope.h

@@ -64,6 +64,8 @@ class Scope : public ScopeBase {
 
       ComponentBase* find_component(perm_string by_name);
 
+      Signal* find_signal(perm_string by_name);
+
     public:
       void dump_scope(ostream&out) const;
 

vhdlpp/sequential.h

@@ -33,6 +33,7 @@ class SequentialStmt  : public LineInfo {
       virtual ~SequentialStmt() =0;
 
     public:
+      virtual int elaborate(Entity*ent, Architecture*arc);
       virtual int emit(ostream&out, Entity*entity, Architecture*arc);
       virtual void dump(ostream&out, int indent) const;
 };
@@ -45,6 +46,7 @@ class IfSequential  : public SequentialStmt {
       ~IfSequential();
 
     public:
+      int elaborate(Entity*ent, Architecture*arc);
       int emit(ostream&out, Entity*entity, Architecture*arc);
       void dump(ostream&out, int indent) const;
 
@@ -60,6 +62,7 @@ class SignalSeqAssignment  : public SequentialStmt {
       ~SignalSeqAssignment();
 
     public:
+      int elaborate(Entity*ent, Architecture*arc);
       int emit(ostream&out, Entity*entity, Architecture*arc);
       void dump(ostream&out, int indent) const;
 

vhdlpp/sequential_elaborate.cc

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2011 Stephen Williams (steve@icarus.com)
+ *
+ *    This source code is free software; you can redistribute it
+ *    and/or modify it in source code form under the terms of the GNU
+ *    General Public License as published by the Free Software
+ *    Foundation; either version 2 of the License, or (at your option)
+ *    any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+# include  "sequential.h"
+# include  "expression.h"
+
+int SequentialStmt::elaborate(Entity*, Architecture*)
+{
+      return 0;
+}
+
+int IfSequential::elaborate(Entity*ent, Architecture*arc)
+{
+      int errors = 0;
+
+      for (list<SequentialStmt*>::iterator cur = if_.begin()
+		 ; cur != if_.end() ; ++cur) {
+	    errors += (*cur)->elaborate(ent, arc);
+      }
+
+      for (list<SequentialStmt*>::iterator cur = else_.begin()
+		 ; cur != else_.end() ; ++cur) {
+	    errors += (*cur)->elaborate(ent, arc);
+      }
+
+      return errors;
+}
+
+int SignalSeqAssignment::elaborate(Entity*ent, Architecture*arc)
+{
+      int errors = 0;
+
+      errors += lval_->elaborate_lval(ent, arc);
+
+      return errors;
+}

vhdlpp/vtype.h

@@ -42,9 +42,10 @@ class VType {
       enum vtype_t { VNONE, VBOOL, VLOGIC };
       struct decl_t {
 	  public:
-	    decl_t() : signed_flag(false), type(VNONE), msb(0), lsb(0) { }
+	    decl_t() : reg_flag(false), signed_flag(false), type(VNONE), msb(0), lsb(0) { }
 	    int emit(std::ostream&out, perm_string name) const;
 	  public:
+	    bool reg_flag;
 	    bool signed_flag;
 	    vtype_t type;
 	    long msb, lsb;

vhdlpp/vtype_emit.cc

@@ -27,12 +27,14 @@ using namespace std;
 
 int VType::decl_t::emit(ostream&out, perm_string name) const
 {
+      const char*wire = reg_flag? "reg" : "wire";
+
       switch (type) {
 	  case VType::VNONE:
 	    out << "// N type for " << name << endl;
 	    break;
 	  case VType::VLOGIC:
-	    out << "wire logic ";
+	    out << wire<< " logic ";
 	    if (signed_flag)
 		  out << "signed ";
 	    if (msb != lsb)
@@ -40,7 +42,7 @@ int VType::decl_t::emit(ostream&out, perm_string name) const
 	    out << name << ";" << endl;
 	    break;
 	  case VType::VBOOL:
-	    out << "wire bool ";
+	    out << wire << " bool ";
 	    if (signed_flag)
 		  out << "signed ";
 	    if (msb != lsb)