From 2b7d4dee3d105460e4a8d89f6eee2f93afea8a3f Mon Sep 17 00:00:00 2001
From: Riyyi <riyyi3@gmail.com>
Date: Wed, 31 Aug 2022 21:43:56 +0200
Subject: [PATCH] Emulator: Add LCDC register to PPU

---
 src/emu.cpp |  3 ++-
 src/ppu.cpp | 13 ++++++++++---
 src/ppu.h   | 17 ++++++++++++++++-
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/emu.cpp b/src/emu.cpp
index b4de96d..57f930e 100644
--- a/src/emu.cpp
+++ b/src/emu.cpp
@@ -69,7 +69,8 @@ void Emu::writeMemory(uint32_t address, uint32_t value)
 		if (address == 0xff50) {
 			Loader::the().disableBootrom();
 		}
-		else if (address >= memory.start_address && address <= memory.end_address) {
+
+		if (address >= memory.start_address && address <= memory.end_address) {
 			// Note: ECHO RAM hack
 			if (address >= 0xc000 && address <= 0xddff) {
 				writeMemory(address + (0xe000 - 0xc000), value);
diff --git a/src/ppu.cpp b/src/ppu.cpp
index c7c3569..ed584a9 100644
--- a/src/ppu.cpp
+++ b/src/ppu.cpp
@@ -5,11 +5,13 @@
  * SPDX-License-Identifier: MIT
  */
 
+#include <cstdint> // uint32_t
+
+#include "emu.h"
 #include "ppu.h"
 #include "ruc/format/print.h"
-#include <iostream>
 
-PPU ::PPU(unsigned int frequency)
+PPU ::PPU(uint32_t frequency)
 	: ProcessingUnit(frequency)
 {
 }
@@ -20,5 +22,10 @@ PPU ::~PPU()
 
 void PPU::update()
 {
-	// print("ppu update\n");
+	LCDC lcd_control = static_cast<LCDC>(Emu::the().readMemory(0xff40));
+	if (!(lcd_control & LCDC::LCDandPPUEnable)) {
+		return;
+	}
+
+	print("PPU update\n");
 }
diff --git a/src/ppu.h b/src/ppu.h
index 8c243a9..ba17cef 100644
--- a/src/ppu.h
+++ b/src/ppu.h
@@ -7,11 +7,26 @@
 
 #pragma once
 
+#include <cstdint> // uint8_t, uint32_t
+
 #include "processing-unit.h"
+#include "ruc/meta/core.h"
+
+enum LCDC : uint8_t {
+	None = 0,
+	BGandWindowEnable = BIT(0),
+	OBJEnable = BIT(1),
+	OBJSize = BIT(2),                 // 0 = 8x8, 1 = 8x16
+	BGTileMapArea = BIT(3),           // 0 = 9800-9bff, 1 = 9c00-9fff
+	BGandWindowTileDataArea = BIT(4), // 0 = 8800-97ff, 1 = 8000-8fff
+	WindowEnable = BIT(5),            //
+	WindowTileMapArea = BIT(6),       // 0 = 9800-9bff, 1 = 9c00-9fff
+	LCDandPPUEnable = BIT(7),
+};
 
 class PPU final : public ProcessingUnit {
 public:
-	PPU(unsigned int frequency);
+	PPU(uint32_t frequency);
 	virtual ~PPU();
 
 	virtual void update() override;