From eceb8d790b0d9b7ae3e3b0c2d65c29bd74285e64 Mon Sep 17 00:00:00 2001
From: Sour <mesenemu@gmail.com>
Date: Tue, 26 May 2020 00:14:19 -0400
Subject: [PATCH] GB: PPU - Removed unnecessary sort operation

---
 Core/GbPpu.cpp | 17 ++++-------------
 Core/GbPpu.h   |  1 -
 2 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/Core/GbPpu.cpp b/Core/GbPpu.cpp
index dc432fe..e847a6a 100644
--- a/Core/GbPpu.cpp
+++ b/Core/GbPpu.cpp
@@ -111,7 +111,6 @@ void GbPpu::ExecCycle()
 		case 4: {
 			if(_state.Scanline < 144) {
 				_spriteCount = 0;
-				_prevSprite = 0;
 				ChangeMode(PpuMode::OamEvaluation);
 			} else if(_state.Scanline == 144) {
 				ChangeMode(PpuMode::VBlank);
@@ -123,14 +122,6 @@ void GbPpu::ExecCycle()
 
 		case 84: {
 			if(_state.Scanline < 144) {
-				std::sort(_spriteIndexes, _spriteIndexes + _spriteCount, [=](uint8_t a, uint8_t b) {
-					if(_oam[a + 1] == _oam[b + 1]) {
-						return a < b;
-					} else {
-						return _oam[a + 1] < _oam[b + 1];
-					}
-				});
-				std::sort(_spriteX, _spriteX + _spriteCount);
 				ChangeMode(PpuMode::Drawing);
 				ResetRenderer();
 			}
@@ -319,11 +310,11 @@ void GbPpu::ClockSpriteFetcher()
 
 void GbPpu::FindNextSprite()
 {
-	if(_prevSprite < _spriteCount && _fetchSprite < 0 && (_state.SpritesEnabled || _state.CgbEnabled)) {
-		for(int i = _prevSprite; i < _spriteCount; i++) {
+	if(_fetchSprite < 0 && (_state.SpritesEnabled || _state.CgbEnabled)) {
+		for(int i = 0; i < _spriteCount; i++) {
 			if((int)_spriteX[i] - 8 == _drawnPixels) {
 				_fetchSprite = _spriteIndexes[i];
-				_prevSprite++;
+				_spriteX[i] = 0xFF; //Prevent processing the same sprite again
 				_oamFetcher.Step = 0;
 				break;
 			}
@@ -729,7 +720,7 @@ void GbPpu::Serialize(Serializer& s)
 	s.Stream(
 		_bgFetcher.Attributes, _bgFetcher.Step, _bgFetcher.Addr, _bgFetcher.LowByte, _bgFetcher.HighByte,
 		_oamFetcher.Attributes, _oamFetcher.Step, _oamFetcher.Addr, _oamFetcher.LowByte, _oamFetcher.HighByte,
-		_drawnPixels, _fetchColumn, _fetchWindow, _fetchSprite, _spriteCount, _prevSprite,
+		_drawnPixels, _fetchColumn, _fetchWindow, _fetchSprite, _spriteCount,
 		_bgFifo.Position, _bgFifo.Size, _oamFifo.Position, _oamFifo.Size
 	);
 
diff --git a/Core/GbPpu.h b/Core/GbPpu.h
index 0c8fbc4..2a8a52f 100644
--- a/Core/GbPpu.h
+++ b/Core/GbPpu.h
@@ -38,7 +38,6 @@ private:
 	bool _fetchWindow = false;
 
 	int16_t _fetchSprite = -1;
-	uint8_t _prevSprite = 0;
 	uint8_t _spriteCount = 0;
 	uint8_t _spriteX[10] = {};
 	uint8_t _spriteIndexes[10] = {};