emulator: Make sure index is valid when looking up an output value

2 files changed, 5 insertions, 3 deletions

diff --git a/emulator.cpp b/emulator.cpp
index dfcf78e..46abe5f 100644
--- a/emulator.cpp
+++ b/emulator.cpp
@@ -93,8 +93,10 @@ emulator::set_value(
 }
 
 value *
-emulator::get_output_value(int index)
+emulator::get_output_value(unsigned int index)
 {
-	//XXX: Make sure not to go over bounds.
+	if (index >= m_out_regs.size()) {
+		return NULL;
+	}
 	return m_out_regs[index]->simplify();
 }
diff --git a/emulator.h b/emulator.h
index 3f64ca4..f1a3437 100644
--- a/emulator.h
+++ b/emulator.h
@@ -23,7 +23,7 @@ public:
 	void set_value(
 		register_address addr,
 		value * val);
-	value * get_output_value(int index);
+	value * get_output_value(unsigned int index);
 
 private:
 	program_loader * m_loader;