added cartridge loading

NES Emulator/CMakeLists.txt

@@ -1,3 +1,11 @@
 cmake_minimum_required (VERSION 3.8)
 
-add_executable (CMakeTarget "main.c"  "cpu.h" "types.h" "bus.h" "bus.c" "cartridge.h" "cpu.c" "cartridge.c")
+add_executable (nesemu "main.c"  "cpu.h" "types.h" "bus.h" "bus.c" "cartridge.h" "cpu.c" "cartridge.c")
+
+if(MSVC)
+target_compile_definitions(nesemu PUBLIC _CRT_SECURE_NO_WARNINGS)
+endif()
+
+add_custom_command(TARGET nesemu POST_BUILD
+	COMMAND ${CMAKE_COMMAND} -E copy_directory ${CMAKE_SOURCE_DIR}/roms $<TARGET_FILE_DIR:nesemu>/roms
+)

NES Emulator/bus.c

@@ -26,7 +26,7 @@ struct Bus* createBus()
 	bus->cpu = createCPU(bus);
 
 	// Create and insert cartridge
-	bus->cartridge = createCartridge(bus, "nestest.nes");
+	bus->cartridge = createCartridge(bus, "roms/nestest.nes");
 
 	return bus;
 }
@@ -42,10 +42,12 @@ void destroyBus(struct Bus* bus)
 
 Byte Read(struct Bus* bus, Word addr)
 {
+	Byte val = 0;
+
 	// Return from the appropriate device depending on the address
 	if (addr <= 0x1FFF)	// RAM (or one of the mirrored addresses)
 	{
-		return bus->ram[addr & 0x7FF];
+		val = bus->ram[addr & 0x7FF];
 	}
 	else if (0x4020 <= addr && addr <= 0xFFFF)	// Cartridge space
 	{
@@ -56,6 +58,8 @@ Byte Read(struct Bus* bus, Word addr)
 		fprintf(stderr, "Access violation at $%x", addr);
 		exit(1);
 	}
+
+	return val;
 }
 
 void Write(struct Bus* bus, Word addr, Byte val)

NES Emulator/cartridge.c

@@ -4,6 +4,33 @@
 
 #include "bus.h"
 
+struct INES_Header
+{
+	Byte nestext[4];
+	Byte prg_rom_size;
+	Byte chr_rom_size;
+	
+	struct
+	{
+		Byte mirror : 1;
+		Byte battery : 1;
+		Byte trainer : 1;
+		Byte ignore_mirror : 1;
+		Byte mapper_lower_nibble : 4;
+	} Flags6;
+
+	struct
+	{
+		Byte vs : 1;
+		Byte playchoice : 1;
+		Byte nes20 : 2;
+		Byte mapper_upper_nibble : 4;
+	} Flags7;
+
+	Byte prg_ram_size;
+	Byte unused[7];
+};
+
 struct Cartridge* createCartridge(struct Bus* parent, const char* filepath)
 {
 	struct Cartridge* cartridge = (struct Cartridge*)malloc(sizeof(struct Cartridge));
@@ -13,13 +40,35 @@ struct Cartridge* createCartridge(struct Bus* parent, const char* filepath)
 		exit(1);
 	}
 
-	cartridge->memory = NULL;
+	// Open ROM
+	FILE* fp = fopen(filepath, "rb");
+	
+	// Read header
+	struct INES_Header header;
+	fread(&header, sizeof(header), 1, fp);
+
+	cartridge->prg_rom = (Byte*)malloc(0x4000 * (size_t)header.prg_rom_size);
+	if (cartridge->prg_rom == NULL)
+	{
+		fprintf(stderr, "Failed to allocate PRG memory for cartridge, aborting.\n");
+		exit(1);
+	}
+
+	cartridge->chr_rom = (Byte*)malloc(0x2000 * (size_t)header.chr_rom_size);
+	if (cartridge->prg_rom == NULL)
+	{
+		fprintf(stderr, "Failed to allocate CHR memory for cartridge, aborting.\n");
+		exit(1);
+	}
+
 	cartridge->bus = parent;
 	return cartridge;
 }
 
 void destroyCartridge(struct Cartridge* cartridge)
 {
-	// free(cartridge->memory);
+	free(cartridge->chr_rom);
+	free(cartridge->prg_rom);
+
 	free(cartridge);
 }

NES Emulator/cartridge.h

@@ -7,7 +7,8 @@ struct Bus;
 
 struct Cartridge
 {
-	Byte* memory;
+	Byte* prg_rom;
+	Byte* chr_rom;
 
 	struct Bus* bus;
 };