Collect required packages as compilation progresses

tgt-vhdl/stmt.cc

@@ -25,10 +25,22 @@
 
 /*
  * Generate VHDL for the $display system task.
- * TODO: How is this going to work??
+ * This is implemented using the functions in std.textio. Each
+ * parameter is written to a line variable in the process and
+ * then the line is written to the special variable `Output'
+ * (which represents the console). Subsequent $displays will use
+ * the same line variable.
+ *
+ * It's possible, although quite unlikely, that there will be
+ * name collision with an existing variable called
+ * `Verilog_Display_Line' - do something about this? It's also
+ * possible for there to be a name collision with the special
+ * variable `Output'.
  */
 static int draw_stask_display(vhdl_process *proc, ivl_statement_t stmt)
 {
+   require_package("std.textio");
+   
    return 0;
 }
 

tgt-vhdl/vhdl.cc

@@ -27,11 +27,18 @@
 #include <cstdio>
 #include <cassert>
 #include <cstring>
+#include <list>
 
 static int g_errors = 0;  // Total number of errors encountered
 
 static entity_list_t g_entities;  // All entities to emit
 
+typedef std::string package_name_t;
+typedef std::list<package_name_t> require_list_t;
+
+static require_list_t g_requires;  // External packages required
+
+
 /*
  * Called when an unrecoverable problem is encountered.
  */
@@ -71,6 +78,21 @@ void remember_entity(vhdl_entity* ent)
    g_entities.push_back(ent);
 }
 
+/*
+ * Add a package to the list of packages that should be
+ * use-ed at the start of the program.
+ */
+void require_package(const char *name)
+{
+   package_name_t pname(name);
+   require_list_t::iterator it;
+   for (it = g_requires.begin(); it != g_requires.end(); ++it) {
+      if (*it == pname)
+         return;
+   }
+   g_requires.push_back(pname);
+}
+
 extern "C" int target_design(ivl_design_t des)
 {
    ivl_scope_t *roots;
@@ -86,14 +108,25 @@ extern "C" int target_design(ivl_design_t des)
    const char *ofname = ivl_design_flag(des, "-o");
    std::ofstream outfile(ofname);
 
-   entity_list_t::const_iterator it;
+   // Write all the required packages (and libraries?)
-   for (it = g_entities.begin(); it != g_entities.end(); ++it)
+   //outfile << "library ieee;" << std::endl;
+   for (require_list_t::iterator it = g_requires.begin();
+        it != g_requires.end();
+        ++it)
+      outfile << "use " << *it << ".all;" << std::endl;
+   outfile << std::endl;
+   
+   for (entity_list_t::iterator it = g_entities.begin();
+        it != g_entities.end();
+        ++it)
       (*it)->emit(outfile);
    
    outfile.close();
 
    // Clean up
-   for (it = g_entities.begin(); it != g_entities.end(); ++it)
+   for (entity_list_t::iterator it = g_entities.begin();
+        it != g_entities.end();
+        ++it)
       delete (*it);
    g_entities.clear();
    

tgt-vhdl/vhdl_target.h

@@ -16,6 +16,7 @@ int draw_stmt(vhdl_process *proc, ivl_statement_t stmt);
 
 void remember_entity(vhdl_entity *ent);
 vhdl_entity *find_entity(const std::string &tname);
+void require_package(const char *name);
 
 #endif /* #ifndef INC_VHDL_TARGET_H */