Add forward declarations for functions

This patch adds a forward declaration for every user funciton.
This fixes VHDL compile problems if a function calls another
before it has been declared.

tgt-vhdl/scope.cc

@@ -529,6 +529,11 @@ static int draw_function(ivl_scope_t scope, ivl_scope_t parent)
    }
    set_active_entity(NULL);
 
+   // Add a forward declaration too in case it is called by
+   // another function that has already been added
+   ent->get_arch()->get_scope()->add_forward_decl
+      (new vhdl_forward_fdecl(func));
+   
    ent->get_arch()->get_scope()->add_decl(func);   
    return 0;
 }

tgt-vhdl/vhdl_syntax.cc

@@ -48,6 +48,11 @@ void vhdl_scope::add_decl(vhdl_decl *decl)
    decls_.push_back(decl);
 }
 
+void vhdl_scope::add_forward_decl(vhdl_decl *decl)
+{
+   decls_.push_front(decl);
+}
+
 vhdl_decl *vhdl_scope::get_decl(const std::string &name) const
 {
    decl_list_t::const_iterator it;
@@ -831,6 +836,16 @@ void vhdl_function::emit(std::ostream &of, int level) const
    of << "end function;";
 }
 
+void vhdl_forward_fdecl::emit(std::ostream &of, int level) const
+{
+   of << "function " << f_->get_name() << " (";
+   emit_children<vhdl_decl>(of, f_->scope_.get_decls(), level, ";");
+   of << ") ";
+   newline(of, level);
+   of << "return " << f_->type_->get_string() << ";";
+   newline(of, level);
+}
+
 void vhdl_param_decl::emit(std::ostream &of, int level) const
 {
    of << name_ << " : ";

tgt-vhdl/vhdl_syntax.hh

@@ -608,6 +608,7 @@ public:
    ~vhdl_scope();
    
    void add_decl(vhdl_decl *decl);
+   void add_forward_decl(vhdl_decl *decl);
    vhdl_decl *get_decl(const std::string &name) const;
    bool have_declared(const std::string &name) const;
    bool contained_within(const vhdl_scope *other) const;
@@ -647,6 +648,7 @@ protected:
 
 
 class vhdl_function : public vhdl_decl, public vhdl_procedural {
+   friend class vhdl_forward_fdecl;
 public:
    vhdl_function(const char *name, vhdl_type *ret_type);
    
@@ -657,6 +659,16 @@ private:
    vhdl_scope variables_;
 };
 
+class vhdl_forward_fdecl : public vhdl_decl {
+public:
+   vhdl_forward_fdecl(const vhdl_function *f)
+      : vhdl_decl((f->get_name() + "_Forward").c_str()), f_(f) {}
+
+   void emit(std::ostream &of, int level) const;
+private:
+   const vhdl_function *f_;
+};
+
 
 class vhdl_process : public vhdl_conc_stmt, public vhdl_procedural {
 public: