6 files changed, 22 insertions, 17 deletions
diff --git a/src/sim/controller.cc b/src/sim/controller.cc
index 17937eb..622f1dc 100644
--- a/src/sim/controller.cc
+++ b/src/sim/controller.cc
@@ -16,10 +16,9 @@ Controller::Controller(Stage *stage, Storage *storage, bool is_pipelined)
 
 void Controller::run_for(int number)
 {
-	InstrDTO instr;
 	int i;
 	for (i = 0; i < number; ++i) {
-		this->advance(instr, OK);
+		this->advance(OK);
 	}
 }
 
@@ -29,11 +28,11 @@ std::array<int, GPR_NUM> Controller::get_gprs() { return this->gprs; }
 
 int Controller::get_pc() { return this->pc; }
 
-Response Controller::advance(InstrDTO &next_instr, Response p)
+InstrDTO *Controller::advance(Response p)
 {
-	Response r;
+	InstrDTO *r;
 
-	r = this->next->advance(next_instr, p);
+	r = this->next->advance(p);
 	++this->clock_cycle;
 	return r;
 }
diff --git a/src/sim/ex.cc b/src/sim/ex.cc
index 5b561f8..3a1e92c 100644
--- a/src/sim/ex.cc
+++ b/src/sim/ex.cc
@@ -6,4 +6,4 @@
 
 EX::EX(Stage *stage) : Stage(stage) { this->id = EXEC; }
 
-Response EX::advance(InstrDTO &next_instr, Response p) { return OK; }
+InstrDTO *EX::advance(Response p) { return nullptr; }
diff --git a/src/sim/id.cc b/src/sim/id.cc
index da7b55c..969cb9d 100644
--- a/src/sim/id.cc
+++ b/src/sim/id.cc
@@ -8,22 +8,24 @@
 
 ID::ID(Stage *stage) : Stage(stage) { this->id = DCDE; }
 
-Response ID::advance(InstrDTO &next_instr, Response p)
+InstrDTO *ID::advance(Response p)
 {
+	InstrDTO *r = nullptr;
 	Response n;
 
 	this->advance_helper();
 	if (this->status == OK && p == OK) {
-	  // mutual consent
+		// mutual consent
 		this->curr_instr->set_time_of(this->id, this->clock_cycle);
-		next_instr = *this->curr_instr;
+		r = new InstrDTO(*this->curr_instr);
+		delete curr_instr;
 		curr_instr = nullptr;
 	}
 
 	n = (p != OK || this->status != OK) ? BLOCKED : OK;
 	// the power of consent
-	n = this->next->advance(*curr_instr, n);
-	return this->status;
+	this->curr_instr = this->next->advance(n);
+	return r;
 }
 
 void ID::get_instr_fields(
diff --git a/src/sim/if.cc b/src/sim/if.cc
index 3d53ad3..43132ed 100644
--- a/src/sim/if.cc
+++ b/src/sim/if.cc
@@ -6,17 +6,21 @@
 
 IF::IF(Stage *stage) : Stage(stage) { this->id = FETCH; }
 
-Response IF::advance(InstrDTO &next_instr, Response p)
+InstrDTO *IF::advance(Response p)
 {
+	InstrDTO *r = nullptr;
+
 	this->advance_helper();
 	if (this->status == OK && p == OK) {
 		// mutual consent
 		++this->pc;
 		this->curr_instr->set_time_of(this->id, this->clock_cycle);
-		next_instr = *this->curr_instr;
+		r = new InstrDTO(*this->curr_instr);
+		delete curr_instr;
 		curr_instr = nullptr;
 	}
-	return this->status;
+
+	return r;
 }
 
 void IF::advance_helper()
diff --git a/src/sim/mm.cc b/src/sim/mm.cc
index f394420..5bc5836 100644
--- a/src/sim/mm.cc
+++ b/src/sim/mm.cc
@@ -6,7 +6,7 @@
 
 MM::MM(Stage *stage) : Stage(stage) { this->id = MEM; } 
 
-Response MM::advance(InstrDTO &next_instr, Response p)
+InstrDTO *MM::advance(Response p)
 {
-	return OK;
+	return nullptr;
 }
diff --git a/src/sim/wb.cc b/src/sim/wb.cc
index bdea65a..7a8d64c 100644
--- a/src/sim/wb.cc
+++ b/src/sim/wb.cc
@@ -6,4 +6,4 @@
 
 WB::WB(Stage *stage) : Stage(stage) { this->id = WRITE; }
 
-Response WB::advance(InstrDTO &next_instr, Response p) { return OK; }
+InstrDTO *WB::advance(Response p) { return nullptr; }