started opcodes

NES Emulator/cpu.c

@@ -13,6 +13,9 @@ struct CPU* createCPU(struct Bus* parent)
 		exit(1);
 	}
 
+	// TODO: THIS IS JUST FOR THE TEST ROM
+	cpu->pc = 0xC000;
+
 	cpu->bus = parent;
 	return cpu;
 }
@@ -21,3 +24,39 @@ void destroyCPU(struct CPU* cpu)
 {
 	free(cpu);
 }
+
+void tickCPU(struct CPU* cpu)
+{
+	if (cpu->fetchedVal != 0)
+	{
+		cpu->fetchedVal--;
+		return;
+	}
+
+	fetch(cpu);
+	execute(cpu);
+}
+
+void tickInstr(struct CPU* cpu)
+{
+	while (cpu->remainingCycles > 1)
+		tickCPU(cpu);
+}
+
+void fetch(struct CPU* cpu)
+{
+	Byte opcodeVal = readBus(cpu->bus, cpu->pc);
+	cpu->currentOpcode = OPCODE_TABLE + opcodeVal;
+
+	if (cpu->currentOpcode->op == Unknown)
+	{
+		fprintf(stderr, "Unknown opcode: %x", opcodeVal);
+		exit(1);
+	}
+
+
+}
+
+void execute(struct CPU* cpu)
+{
+}