From 595791cee0e2db4a99dd684d30392653af8496d7 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 18 Jun 2016 08:51:18 -0400
Subject: [PATCH] Made the base 6522 class more abstract: you must now opt-in
 if you want the IRQ line to be sent to a delegate.

---
 Components/6522/6522.hpp  | 34 ++++++++++++++++++++++------------
 Machines/Vic-20/Vic20.hpp |  6 +++---
 2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/Components/6522/6522.hpp b/Components/6522/6522.hpp
index 15458d465..816f7ce8d 100644
--- a/Components/6522/6522.hpp
+++ b/Components/6522/6522.hpp
@@ -14,11 +14,6 @@
 
 namespace MOS {
 
-class MOS6522Delegate {
-	public:
-		virtual void mos6522_did_change_interrupt_status(void *mos6522) = 0;
-};
-
 template <class T> class MOS6522 {
 	private:
 		enum InterruptFlag: uint8_t {
@@ -181,11 +176,6 @@ template <class T> class MOS6522 {
 			return !!interrupt_status;
 		}
 
-		void set_delegate(MOS6522Delegate *delegate)
-		{
-			_delegate = delegate;
-		}
-
 		MOS6522() :
 			_timer_is_running{false, false},
 			_last_posted_interrupt_status(false)
@@ -197,7 +187,6 @@ template <class T> class MOS6522 {
 		void set_port_output(int port, uint8_t value)	{}
 
 		// Delegate and communications
-		MOS6522Delegate *_delegate;
 		bool _last_posted_interrupt_status;
 		inline void reevaluate_interrupts()
 		{
@@ -205,7 +194,7 @@ template <class T> class MOS6522 {
 			if(new_interrupt_status != _last_posted_interrupt_status)
 			{
 				_last_posted_interrupt_status = new_interrupt_status;
-				if(_delegate) _delegate->mos6522_did_change_interrupt_status(this);
+				static_cast<T *>(this)->set_interrupt_status(new_interrupt_status);
 			}
 		}
 
@@ -228,6 +217,27 @@ template <class T> class MOS6522 {
 		bool _timer_is_running[2];
 };
 
+class MOS6522IRQDelegate {
+	public:
+		class Delegate {
+			public:
+				virtual void mos6522_did_change_interrupt_status(void *mos6522) = 0;
+		};
+
+		void set_delegate(Delegate *delegate)
+		{
+			_delegate = delegate;
+		}
+
+		void set_interrupt_status(bool new_status)
+		{
+			if(_delegate) _delegate->mos6522_did_change_interrupt_status(this);
+		}
+
+	private:
+		Delegate *_delegate;
+};
+
 }
 
 #endif /* _522_hpp */
diff --git a/Machines/Vic-20/Vic20.hpp b/Machines/Vic-20/Vic20.hpp
index 0910b8f40..ea4d26e3b 100644
--- a/Machines/Vic-20/Vic20.hpp
+++ b/Machines/Vic-20/Vic20.hpp
@@ -44,10 +44,10 @@ enum Key: uint16_t {
 	Key9		= key(0, 0x10),		KeyPlus		= key(0, 0x20),		KeyGBP			= key(0, 0x40),		KeyDelete	= key(0, 0x80),
 };
 
-class UserPortVIA: public MOS::MOS6522<UserPortVIA> {
+class UserPortVIA: public MOS::MOS6522<UserPortVIA>, public MOS::MOS6522IRQDelegate {
 };
 
-class KeyboardVIA: public MOS::MOS6522<KeyboardVIA> {
+class KeyboardVIA: public MOS::MOS6522<KeyboardVIA>, public MOS::MOS6522IRQDelegate {
 	public:
 		void set_key_state(Key key, bool isPressed) {
 			if(isPressed)
@@ -88,7 +88,7 @@ class KeyboardVIA: public MOS::MOS6522<KeyboardVIA> {
 		uint8_t _activation_mask;
 };
 
-class Machine: public CPU6502::Processor<Machine>, public CRTMachine::Machine, public MOS::MOS6522Delegate {
+class Machine: public CPU6502::Processor<Machine>, public CRTMachine::Machine, public MOS::MOS6522IRQDelegate::Delegate {
 	public:
 		Machine();
 		~Machine();