Support functions for converting (un)signed -> boolean

tgt-vhdl/Makefile.in

@@ -50,7 +50,7 @@ dep:
 	mv $*.d dep
 
 O = vhdl.o vhdl_element.o vhdl_type.o vhdl_syntax.o scope.o process.o \
-	stmt.o expr.o lpm.o display.o
+	stmt.o expr.o lpm.o display.o support.o
 
 ifeq (@WIN32@,yes)
   TGTLDFLAGS=-L.. -livl

tgt-vhdl/support.cc

@@ -0,0 +1,50 @@
+/*
+ *  Support functions for VHDL output.
+ *
+ *  Copyright (C) 2008  Nick Gasson (nick@nickg.me.uk)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it 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.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "vhdl_target.h"
+#include "support.hh"
+
+#include <cassert>
+
+void unsigned_to_boolean::emit(std::ostream &of, int level) const
+{
+   of << "function " << function_name()
+      << "(X : unsigned) return Boolean is";
+   newline(of, level);
+   of << "begin";
+   newline(of, indent(level));
+   of << "return X /= To_Unsigned(0, X'Length);";
+   newline(of, level);
+   of << "end function;";
+   newline(of, level);
+}
+
+void signed_to_boolean::emit(std::ostream &of, int level) const
+{
+   of << "function " << function_name()
+      << "(X : signed) return Boolean is";
+   newline(of, level);
+   of << "begin";
+   newline(of, indent(level));
+   of << "return X /= To_Signed(0, X'Length);";
+   newline(of, level);
+   of << "end function;";
+   newline(of, level);
+}

tgt-vhdl/support.hh

@@ -0,0 +1,45 @@
+/*
+ *  Support functions for VHDL output.
+ *
+ *  Copyright (C) 2008  Nick Gasson (nick@nickg.me.uk)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it 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.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef INC_SUPPORT_HH
+#define INC_SUPPORT_HH
+
+#include "vhdl_syntax.hh"
+
+class unsigned_to_boolean : public vhdl_function {
+public:
+   unsigned_to_boolean()
+      : vhdl_function(function_name(), vhdl_type::boolean()) {}
+   void emit(std::ostream &of, int level) const;
+
+   static const char *function_name() { return "Unsigned_To_Boolean"; }
+};
+
+
+class signed_to_boolean : public vhdl_function {
+public:
+   signed_to_boolean()
+      : vhdl_function(function_name(), vhdl_type::boolean()) {}
+   void emit(std::ostream &of, int level) const;
+
+   static const char *function_name() { return "Signed_To_Boolean"; }
+};
+
+#endif

tgt-vhdl/vhdl_syntax.cc

@@ -21,6 +21,9 @@
 #include "vhdl_syntax.hh"
 #include "vhdl_helper.hh"
 
+#include "vhdl_target.h"
+#include "support.hh"
+
 #include <cassert>
 #include <iostream>
 #include <typeinfo>
@@ -428,6 +431,25 @@ vhdl_expr *vhdl_expr::cast(const vhdl_type *to)
          return new vhdl_binop_expr
             (this, VHDL_BINOP_EQ, one, vhdl_type::boolean());
       }
+      else if (type_->get_name() == VHDL_TYPE_UNSIGNED) {
+         // Need to use a support function for this conversion
+         require_support_function<unsigned_to_boolean>();
+
+         vhdl_fcall *conv =
+            new vhdl_fcall(unsigned_to_boolean::function_name(),
+                           vhdl_type::boolean());
+         conv->add_expr(this);
+         return conv;
+      }
+      else if (type_->get_name() == VHDL_TYPE_SIGNED) {
+         require_support_function<signed_to_boolean>();
+
+         vhdl_fcall *conv =
+            new vhdl_fcall(signed_to_boolean::function_name(),
+                           vhdl_type::boolean());
+         conv->add_expr(this);
+         return conv;
+      }
       else {
          assert(false);
       }

tgt-vhdl/vhdl_syntax.hh

@@ -614,7 +614,7 @@ class vhdl_function : public vhdl_decl, public vhdl_procedural {
 public:
    vhdl_function(const char *name, vhdl_type *ret_type);
    
-   void emit(std::ostream &of, int level) const;
+   virtual void emit(std::ostream &of, int level) const;
    vhdl_scope *get_scope() { return &variables_; }
    void add_param(vhdl_param_decl *p) { scope_.add_decl(p); }
 private:

tgt-vhdl/vhdl_target.h

@@ -41,5 +41,13 @@ ivl_signal_t find_signal_named(const string &name, const vhdl_scope *scope);
 int draw_stask_display(vhdl_procedural *proc, stmt_container *container,
                        ivl_statement_t stmt, bool newline = true);
 
+template <class T>
+void require_support_function()
+{
+   vhdl_scope *scope = get_active_entity()->get_arch()->get_scope();
+   if (!scope->have_declared(T::function_name()))
+      scope->add_decl(new T);
+}
+
 #endif /* #ifndef INC_VHDL_TARGET_H */