From 9ab5ac3c13a0d4ea6189d280a7383fd10a3aab01 Mon Sep 17 00:00:00 2001
From: Lauchmelder <robert.trololo@gmail.com>
Date: Sat, 30 Oct 2021 19:42:17 +0200
Subject: [PATCH] added ppu read latch

---
 NES Emulator/ppu.c | 6 ++++--
 NES Emulator/ppu.h | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/NES Emulator/ppu.c b/NES Emulator/ppu.c
index fb258ac..4e20927 100644
--- a/NES Emulator/ppu.c	
+++ b/NES Emulator/ppu.c	
@@ -131,7 +131,8 @@ Byte ppuRead(struct PPU* ppu, Word addr)
 	{
 		if (ppu->ppuAddress.raw < 0x2000)
 		{
-			val = readCartridgePPU(ppu->bus->cartridge, ppu->ppuAddress.raw);
+			val = ppu->ppuReadLatch;
+			ppu->ppuReadLatch = readCartridgePPU(ppu->bus->cartridge, ppu->ppuAddress.raw);
 		}
 		else if (0x2000 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x3F00)
 		{
@@ -140,7 +141,8 @@ Byte ppuRead(struct PPU* ppu, Word addr)
 			if (effectiveAddress >= 0x2800)
 				effectiveAddress -= 0x0400;
 
-			val = ppu->nameTables[0][(effectiveAddress - 0x2000) & 0x0FFF];
+			val = ppu->ppuReadLatch;
+			ppu->ppuReadLatch = ppu->nameTables[0][(effectiveAddress - 0x2000) & 0x0FFF];
 		}
 		else if (0x3F00 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x4000)
 		{
diff --git a/NES Emulator/ppu.h b/NES Emulator/ppu.h
index d0259cd..7d3c3bc 100644
--- a/NES Emulator/ppu.h	
+++ b/NES Emulator/ppu.h	
@@ -113,6 +113,7 @@ struct PPU
 		Word raw;
 	} ppuAddress;
 	Byte ppuAddressWriteTarget;
+	Byte ppuReadLatch;
 
 	Byte oamdma;