Initial commit

NES Emulator/bus.c

@@ -0,0 +1,77 @@
+#include "bus.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "cpu.h"
+#include "cartridge.h"
+
+struct Bus* createBus()
+{
+	struct Bus* bus = (struct Bus*)malloc(sizeof(struct Bus));
+	if (bus == NULL)
+	{
+		fprintf(stderr, "Failed to create Bus object, aborting.");
+		exit(1);
+	}
+
+	// 2KB of memory, equates to 2048 Bytes (0x800)
+	bus->ram = (Byte*)malloc(0x800);
+	if (bus->ram == NULL)
+	{
+		fprintf(stderr, "Failed to allocate memory for NES RAM, aborting.");
+		exit(1);
+	}
+
+	// Create CPU and attach it
+	bus->cpu = createCPU(bus);
+
+	// Create and insert cartridge
+	bus->cartridge = createCartridge(bus, "nestest.nes");
+
+	return bus;
+}
+
+void destroyBus(struct Bus* bus)
+{
+	destroyCartridge(bus->cartridge);
+	destroyCPU(bus->cpu);
+	
+	free(bus->ram);
+	free(bus);
+}
+
+Byte Read(struct Bus* bus, Word addr)
+{
+	// Return from the appropriate device depending on the address
+	if (addr <= 0x1FFF)	// RAM (or one of the mirrored addresses)
+	{
+		return bus->ram[addr & 0x7FF];
+	}
+	else if (0x4020 <= addr && addr <= 0xFFFF)	// Cartridge space
+	{
+		// rom->read()
+	}
+	else
+	{
+		fprintf(stderr, "Access violation at $%x", addr);
+		exit(1);
+	}
+}
+
+void Write(struct Bus* bus, Word addr, Byte val)
+{
+	// Write to the appropriate memory or device
+	if (addr <= 0x1FFF)	// RAM (or one of the mirrored addresses)
+	{
+		bus->ram[addr & 0x7FF] = val;
+	}
+	else if (0x4020 <= addr && addr <= 0xFFFF)	// Cartridge space
+	{
+		// rom->write()
+	}
+	else
+	{
+		fprintf(stderr, "Access violation at $%x", addr);
+		exit(1);
+	}
+}