From 44da7de651dce8e348256a5d24e6e3866c548264 Mon Sep 17 00:00:00 2001
From: Maciej Suminski <maciej.suminski@cern.ch>
Date: Wed, 8 Oct 2014 10:26:37 +0200
Subject: [PATCH] vhdlpp: prange_t may have the direction determined
 automatically.

---
 vhdlpp/parse_types.h      |  6 +++++-
 vhdlpp/sequential_emit.cc | 44 ++++++++++++++++++++++++++-------------
 2 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/vhdlpp/parse_types.h b/vhdlpp/parse_types.h
index 2e517127f..625312762 100644
--- a/vhdlpp/parse_types.h
+++ b/vhdlpp/parse_types.h
@@ -71,7 +71,7 @@ class instant_list_t {
 class prange_t {
     public:
       prange_t(Expression* left, Expression* right, bool dir)
-        : left_(left), right_(right), direction_(dir) {}
+        : left_(left), right_(right), direction_(dir), auto_dir_(false) {}
       ~prange_t() { delete left_; delete right_; }
       void dump(ostream&out, int indent) const;
 
@@ -79,12 +79,16 @@ class prange_t {
       inline Expression*lsb() { return direction_? right_: left_;  }
 
       inline bool is_downto() const { return direction_; }
+      inline void set_auto_dir(bool enabled = true) { auto_dir_ = enabled; };
+      inline bool is_auto_dir() const { return auto_dir_; }
+
       inline Expression*expr_left() { return left_; }
       inline Expression*expr_right() { return right_; }
 
     private:
       Expression *left_, *right_;
       bool direction_;
+      bool auto_dir_;
 
     private: //not implemented
       prange_t(const prange_t&);
diff --git a/vhdlpp/sequential_emit.cc b/vhdlpp/sequential_emit.cc
index 4f4b9c705..e046ef756 100644
--- a/vhdlpp/sequential_emit.cc
+++ b/vhdlpp/sequential_emit.cc
@@ -213,21 +213,37 @@ int ForLoopStatement::emit(ostream&out, Entity*ent, Architecture*arc)
       out << "begin : " << scope_name << endl;
       out << "longint \\" << it_ << " ;" << endl;
       out << "for (\\" << it_ << " = ";
-      if (range_->is_downto()) {
-            range_->msb()->emit(out, ent, arc);
-            out << " ; \\" << it_ << " >= ";
-            range_->lsb()->emit(out, ent, arc);
-      } else {
-            range_->lsb()->emit(out, ent, arc);
-            out << " ; \\" << it_ << " <= ";
-            range_->msb()->emit(out, ent, arc);
-      }
+      range_->expr_left()->emit(out, ent, arc);
 
-      out << "; \\" << it_ << " = \\" << it_;
-      if (range_->is_downto())
-	    out << " - 1";
-      else
-	    out << " + 1";
+        // Determining the loop direction at the runtime
+      if (range_->is_auto_dir() || true) {
+            out << " ;\n(";
+            range_->expr_left()->emit(out, ent, arc);
+            out << " < ";
+            range_->expr_right()->emit(out, ent, arc);
+            out << " ? \\" << it_ << " <= ";
+            range_->expr_right()->emit(out, ent, arc);
+            out << " : \\" << it_ << " >= ";
+            range_->expr_right()->emit(out, ent, arc);
+            out << ");\n\\" << it_ << " = \\" << it_ << " + (";
+            range_->expr_left()->emit(out, ent, arc);
+            out << " < ";
+            range_->expr_right()->emit(out, ent, arc);
+            out << " ? 1 : -1)";
+      } else {
+            if (range_->is_downto())
+                out << " ; \\" << it_ << " >= ";
+            else
+                out << " ; \\" << it_ << " <= ";
+            range_->expr_right()->emit(out, ent, arc);
+
+            out << "; \\" << it_ << " = \\" << it_;
+
+            if (range_->is_downto())
+                out << " - 1";
+            else
+                out << " + 1";
+      }
 
       out << ") begin" << endl;