added rom/bus interaction

NES Emulator/bus.c

@@ -28,6 +28,8 @@ struct Bus* createBus()
 	// Create and insert cartridge
 	bus->cartridge = createCartridge(bus, "roms/nestest.nes");
 
+	printf("Reset vector: $%x\n", ((Word)readCartridge(bus->cartridge, 0xFFFD) << 8) | (readCartridge(bus->cartridge, 0xFFFC)));
+
 	return bus;
 }
 
@@ -40,7 +42,7 @@ void destroyBus(struct Bus* bus)
 	free(bus);
 }
 
-Byte Read(struct Bus* bus, Word addr)
+Byte readBus(struct Bus* bus, Word addr)
 {
 	Byte val = 0;
 
@@ -62,9 +64,9 @@ Byte Read(struct Bus* bus, Word addr)
 	return val;
 }
 
-void Write(struct Bus* bus, Word addr, Byte val)
+void writeBus(struct Bus* bus, Word addr, Byte val)
 {
-	// Write to the appropriate memory or device
+	// writeCartridge to the appropriate memory or device
 	if (addr <= 0x1FFF)	// RAM (or one of the mirrored addresses)
 	{
 		bus->ram[addr & 0x7FF] = val;

NES Emulator/bus.h

@@ -22,7 +22,7 @@ struct Bus* createBus();
 void destroyBus(struct Bus* bus);
 
 // Read/Write to and from the bus
-Byte Read(struct Bus* bus, Word addr);
+Byte readBus(struct Bus* bus, Word addr);
-void Write(struct Bus* bus, Word addr, Byte val);
+void writeBus(struct Bus* bus, Word addr, Byte val);
 
 #endif // _BUS_H_

NES Emulator/cartridge.c

@@ -43,7 +43,7 @@ struct Cartridge* createCartridge(struct Bus* parent, const char* filepath)
 	// Open ROM
 	FILE* fp = fopen(filepath, "rb");
 	
-	// Read header
+	// readCartridge header
 	struct INES_Header header;
 	fread(&header, sizeof(header), 1, fp);
 
@@ -55,12 +55,15 @@ struct Cartridge* createCartridge(struct Bus* parent, const char* filepath)
 	}
 
 	cartridge->chr_rom = (Byte*)malloc(0x2000 * (size_t)header.chr_rom_size);
-	if (cartridge->prg_rom == NULL)
+	if (cartridge->chr_rom == NULL)
 	{
 		fprintf(stderr, "Failed to allocate CHR memory for cartridge, aborting.\n");
 		exit(1);
 	}
 
+	fread(cartridge->prg_rom, 0x4000, header.prg_rom_size, fp);
+	fread(cartridge->chr_rom, 0x2000, header.chr_rom_size, fp);
+
 	cartridge->bus = parent;
 	return cartridge;
 }
@@ -72,3 +75,35 @@ void destroyCartridge(struct Cartridge* cartridge)
 
 	free(cartridge);
 }
+
+Byte readCartridge(struct Cartridge* cartridge, Word addr)
+{
+	// TODO: Force M000 mapper for now
+	Byte val = 0;
+
+	if (0x6000 <= addr && addr <= 0x7FFF)	// PRG RAM
+	{
+		// do nothing for now
+	}
+	else if (0x8000 <= addr && addr <= 0xFFFF)	// PRG ROM
+	{
+		val = cartridge->prg_rom[addr & 0x1FFF];
+	}
+
+	return val;
+}
+
+void writeCartridge(struct Cartridge* cartridge, Word addr, Byte val)
+{
+	// TODO: Force M000 mapper for now
+
+	if (0x6000 <= addr && addr <= 0x7FFF)	// PRG RAM
+	{
+		// do nothing for now
+	}
+	else if (0x8000 <= addr && addr <= 0xFFFF)	// PRG ROM
+	{
+		cartridge->prg_rom[addr & 0x1FFF] = val;
+	}
+
+}

NES Emulator/cartridge.h

@@ -16,4 +16,8 @@ struct Cartridge
 struct Cartridge* createCartridge(struct Bus* parent, const char* filepath);
 void destroyCartridge(struct Cartridge* cartridge);
 
+// readCartridge/writeCartridge to and from the cartridge
+Byte readCartridge(struct Cartridge* cartridge, Word addr);
+void writeCartridge(struct Cartridge* cartridge, Word addr, Byte val);
+
 #endif //_CARTRIDGE_H_