From d5e50f5ea0e37126304b9dfdfc52734f188ef7b7 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 26 Jun 2016 12:30:01 -0400
Subject: [PATCH] Got a bit more explicit about how ports are identified on the
 6522.

---
 Components/6522/6522.hpp                      | 21 ++++++++++++-------
 Machines/Vic-20/Vic20.hpp                     |  4 ++--
 .../Mac/Clock SignalTests/MOS6522Bridge.mm    |  2 +-
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/Components/6522/6522.hpp b/Components/6522/6522.hpp
index 509e83109..bf541ac0d 100644
--- a/Components/6522/6522.hpp
+++ b/Components/6522/6522.hpp
@@ -38,6 +38,11 @@ template <class T> class MOS6522 {
 		};
 
 	public:
+		enum Port {
+			A = 0,
+			B = 1
+		};
+
 		/*! Sets a register value. */
 		inline void set_register(int address, uint8_t value)
 		{
@@ -47,12 +52,12 @@ template <class T> class MOS6522 {
 			{
 				case 0x0:
 					_registers.output[1] = value;
-					static_cast<T *>(this)->set_port_output(1, value, _registers.data_direction[1]);	// TODO: handshake
+					static_cast<T *>(this)->set_port_output(Port::B, value, _registers.data_direction[1]);	// TODO: handshake
 				break;
 				case 0xf:
 				case 0x1:
 					_registers.output[0] = value;
-					static_cast<T *>(this)->set_port_output(0, value, _registers.data_direction[0]);	// TODO: handshake
+					static_cast<T *>(this)->set_port_output(Port::A, value, _registers.data_direction[0]);	// TODO: handshake
 				break;
 //					// No handshake, so write directly
 //					_registers.output[0] = value;
@@ -117,9 +122,9 @@ template <class T> class MOS6522 {
 //			printf("6522 %p: %d\n", this, address);
 			switch(address)
 			{
-				case 0x0:	return get_port_input(1, _registers.data_direction[1], _registers.output[1]);
+				case 0x0:	return get_port_input(Port::B, _registers.data_direction[1], _registers.output[1]);
 				case 0xf:	// TODO: handshake, latching
-				case 0x1:	return get_port_input(0, _registers.data_direction[0], _registers.output[0]);
+				case 0x1:	return get_port_input(Port::A, _registers.data_direction[0], _registers.output[0]);
 
 				case 0x2:	return _registers.data_direction[1];
 				case 0x3:	return _registers.data_direction[0];
@@ -152,7 +157,7 @@ template <class T> class MOS6522 {
 			return 0xff;
 		}
 
-		inline void set_control_line_input(int port, int line, bool value)
+		inline void set_control_line_input(Port port, int line, bool value)
 		{
 		}
 
@@ -226,12 +231,12 @@ template <class T> class MOS6522 {
 
 	private:
 		// Expected to be overridden
-		uint8_t get_port_input(int port)										{	return 0xff;	}
-		void set_port_output(int port, uint8_t value, uint8_t direction_mask)	{}
+		uint8_t get_port_input(Port port)										{	return 0xff;	}
+		void set_port_output(Port port, uint8_t value, uint8_t direction_mask)	{}
 //		void set_interrupt_status(bool status)			{}
 
 		// Input/output multiplexer
-		uint8_t get_port_input(int port, uint8_t output_mask, uint8_t output)
+		uint8_t get_port_input(Port port, uint8_t output_mask, uint8_t output)
 		{
 			uint8_t input = static_cast<T *>(this)->get_port_input(port);
 			return (input & ~output_mask) | (output & output_mask);
diff --git a/Machines/Vic-20/Vic20.hpp b/Machines/Vic-20/Vic20.hpp
index cf677b1f0..1862daca8 100644
--- a/Machines/Vic-20/Vic20.hpp
+++ b/Machines/Vic-20/Vic20.hpp
@@ -66,7 +66,7 @@ class KeyboardVIA: public MOS::MOS6522<KeyboardVIA>, public MOS::MOS6522IRQDeleg
 		}
 
 		// to satisfy MOS::MOS6522
-		uint8_t get_port_input(int port) {
+		uint8_t get_port_input(Port port) {
 			if(!port) {
 				uint8_t result = 0xff;
 				for(int c = 0; c < 8; c++)
@@ -80,7 +80,7 @@ class KeyboardVIA: public MOS::MOS6522<KeyboardVIA>, public MOS::MOS6522IRQDeleg
 			return 0xff;
 		}
 
-		void set_port_output(int port, uint8_t value, uint8_t mask) {
+		void set_port_output(Port port, uint8_t value, uint8_t mask) {
 			if(port)
 				_activation_mask = (value & mask) | (~mask);
 		}
diff --git a/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm
index 8dd444a05..ac05933f5 100644
--- a/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm	
+++ b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm	
@@ -23,7 +23,7 @@ class VanillaVIA: public MOS::MOS6522<VanillaVIA> {
 			irq_line = new_status;
 		}
 
-		uint8_t get_port_input(int port)
+		uint8_t get_port_input(Port port)
 		{
 			return port ? port_b_value : port_a_value;
 		}