From a547b7e1d82796fccae0a48e31540749a863190f Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 13 Aug 2016 17:21:25 -0400
Subject: [PATCH] Took basic steps towards supporting memory expansions.

---
 Machines/Commodore/Vic-20/Vic20.cpp | 28 ++++++++++++++++++++++++----
 Machines/Commodore/Vic-20/Vic20.hpp |  8 ++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/Machines/Commodore/Vic-20/Vic20.cpp b/Machines/Commodore/Vic-20/Vic20.cpp
index 097d63cfe..3050216e8 100644
--- a/Machines/Commodore/Vic-20/Vic20.cpp
+++ b/Machines/Commodore/Vic-20/Vic20.cpp
@@ -35,9 +35,33 @@ Machine::Machine() :
 	_tape.set_delegate(this);
 
 	// establish the memory maps
+	set_memory_size(MemorySize::Default);
+
+//	_debugPort.reset(new ::Commodore::Serial::DebugPort);
+//	_debugPort->set_serial_bus(_serialBus);
+//	_serialBus->add_port(_debugPort);
+}
+
+void Machine::set_memory_size(MemorySize size)
+{
 	memset(_processorReadMemoryMap, 0, sizeof(_processorReadMemoryMap));
 	memset(_processorWriteMemoryMap, 0, sizeof(_processorWriteMemoryMap));
 
+	switch(size)
+	{
+		default: break;
+		case ThreeKB:
+			write_to_map(_processorReadMemoryMap, _expansionRAM, 0x0000, 0x1000);
+			write_to_map(_processorWriteMemoryMap, _expansionRAM, 0x0000, 0x1000);
+		break;
+		case ThirtyTwoKB:
+			write_to_map(_processorReadMemoryMap, _expansionRAM, 0x0000, 0x8000);
+			write_to_map(_processorWriteMemoryMap, _expansionRAM, 0x0000, 0x8000);
+		break;
+	}
+
+
+	// install the ROMs and VIC-visible memory
 	write_to_map(_processorReadMemoryMap, _userBASICMemory, 0x0000, sizeof(_userBASICMemory));
 	write_to_map(_processorReadMemoryMap, _screenMemory, 0x1000, sizeof(_screenMemory));
 	write_to_map(_processorReadMemoryMap, _colorMemory, 0x9400, sizeof(_colorMemory));
@@ -48,10 +72,6 @@ Machine::Machine() :
 	write_to_map(_processorWriteMemoryMap, _userBASICMemory, 0x0000, sizeof(_userBASICMemory));
 	write_to_map(_processorWriteMemoryMap, _screenMemory, 0x1000, sizeof(_screenMemory));
 	write_to_map(_processorWriteMemoryMap, _colorMemory, 0x9400, sizeof(_colorMemory));
-
-//	_debugPort.reset(new ::Commodore::Serial::DebugPort);
-//	_debugPort->set_serial_bus(_serialBus);
-//	_serialBus->add_port(_debugPort);
 }
 
 void Machine::write_to_map(uint8_t **map, uint8_t *area, uint16_t address, uint16_t length)
diff --git a/Machines/Commodore/Vic-20/Vic20.hpp b/Machines/Commodore/Vic-20/Vic20.hpp
index 29a1fe3e5..e1b4b8a3c 100644
--- a/Machines/Commodore/Vic-20/Vic20.hpp
+++ b/Machines/Commodore/Vic-20/Vic20.hpp
@@ -32,6 +32,12 @@ enum ROMSlot {
 	Drive
 };
 
+enum MemorySize {
+	Default,
+	ThreeKB,
+	ThirtyTwoKB
+};
+
 #define key(line, mask) (((mask) << 3) | (line))
 
 enum Key: uint16_t {
@@ -259,6 +265,7 @@ class Machine:
 			_userPortVIA->set_joystick_state(input, isPressed);
 			_keyboardVIA->set_joystick_state(input, isPressed);
 		}
+		void set_memory_size(MemorySize size);
 
 		inline void set_use_fast_tape_hack(bool activate) { _use_fast_tape_hack = activate; }
 		inline void set_should_automatically_load_media(bool activate) { _should_automatically_load_media = activate; }
@@ -291,6 +298,7 @@ class Machine:
 		uint8_t _characterROM[0x1000];
 		uint8_t _basicROM[0x2000];
 		uint8_t _kernelROM[0x2000];
+		uint8_t _expansionRAM[0x8000];
 
 		uint8_t *_rom;
 		uint16_t _rom_address, _rom_length;