basic ppu background rendering

src/APU.cpp

@@ -0,0 +1,61 @@
+#include "APU.hpp"
+
+#include "Bus.hpp"
+
+APU::APU(Bus* bus) :
+	bus(bus)
+{
+}
+
+void APU::Powerup()
+{
+	mode = false;
+	disableInterrupt = false;
+}
+
+void APU::Reset()
+{
+	// Nothing for now
+}
+
+void APU::Tick()
+{
+	if (cycles == 0)
+		sequencer = 0;
+	else
+		cycles--;
+
+	if (!APUActionLatch)
+	{
+		APUActionLatch = !APUActionLatch;
+		return;
+	}
+
+	if (sequencer == 14914 || sequencer == 14915)
+	{
+		if(!mode && !disableInterrupt)
+			bus->IRQ();
+
+		if (sequencer == 14915)
+			sequencer = 0;
+	}
+	sequencer++;
+
+	APUActionLatch = !APUActionLatch;
+}
+
+void APU::WriteRegister(Word addr, Byte val)
+{
+	switch (addr)
+	{
+	case 0x4017:
+	{
+		mode = ((val & 0x80) == 0x80);
+		disableInterrupt = ((val & 0x40) == 0x40);
+
+		cycles = 3;
+		if (!APUActionLatch)
+			cycles++;
+	} break;
+	}
+}