From 21a23b3a7a862180dd057321c5fb317c7d9865c4 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Fri, 31 Jul 2020 22:01:11 -0700
Subject: [PATCH] 3DS: Use "wide mode" where applicable for slightly better
 filtering

---
 CHANGES                 |  1 +
 src/platform/3ds/main.c | 43 ++++++++++++++++++++++++-----------------
 2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/CHANGES b/CHANGES
index 938ba84d4..90ae34920 100644
--- a/CHANGES
+++ b/CHANGES
@@ -56,6 +56,7 @@ Other fixes:
  - SM83: Simplify register pair access on big endian
  - Wii: Fix pixelated filtering on interframe blending (fixes mgba.io/i/1830)
 Misc:
+ - 3DS: Use "wide mode" where applicable for slightly better filtering
  - GB: Allow pausing event loop while CPU is blocked
  - GBA: Allow pausing event loop while CPU is blocked
  - Debugger: Keep track of global cycle count
diff --git a/src/platform/3ds/main.c b/src/platform/3ds/main.c
index 2f26c49d1..6ffe46da2 100644
--- a/src/platform/3ds/main.c
+++ b/src/platform/3ds/main.c
@@ -20,6 +20,7 @@
 #include <mgba-util/gui/file-select.h>
 #include <mgba-util/gui/font.h>
 #include <mgba-util/gui/menu.h>
+#include <mgba-util/math.h>
 #include <mgba-util/memory.h>
 
 #include <mgba-util/platform/3ds/3ds-vfs.h>
@@ -114,8 +115,13 @@ static bool _initGpu(void) {
 		return false;
 	}
 
-	topScreen[0] = C3D_RenderTargetCreate(240, 400, GPU_RB_RGB8, 0);
-	topScreen[1] = C3D_RenderTargetCreate(240, 400, GPU_RB_RGB8, 0);
+	if (gfxIsWide()) {
+		topScreen[0] = C3D_RenderTargetCreate(240, 800, GPU_RB_RGB8, 0);
+		topScreen[1] = C3D_RenderTargetCreate(240, 800, GPU_RB_RGB8, 0);
+	} else {
+		topScreen[0] = C3D_RenderTargetCreate(240, 400, GPU_RB_RGB8, 0);
+		topScreen[1] = C3D_RenderTargetCreate(240, 400, GPU_RB_RGB8, 0);
+	}
 	bottomScreen[0] = C3D_RenderTargetCreate(240, 320, GPU_RB_RGB8, 0);
 	bottomScreen[1] = C3D_RenderTargetCreate(240, 320, GPU_RB_RGB8, 0);
 	if (!topScreen[0] || !topScreen[1] || !bottomScreen[0] || !bottomScreen[1]) {
@@ -470,6 +476,7 @@ static u32 _setupTex(int out, bool faded) {
 
 static void _drawTex(struct mCore* core, bool faded, bool both) {
 	unsigned screen_w, screen_h;
+	bool isWide = screenMode >= SM_PA_TOP && gfxIsWide();
 	switch (screenMode) {
 	case SM_PA_BOTTOM:
 		C3D_FrameDrawOn(bottomScreen[doubleBuffer]);
@@ -478,7 +485,7 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 		break;
 	case SM_PA_TOP:
 		C3D_FrameDrawOn(topScreen[doubleBuffer]);
-		screen_w = 400;
+		screen_w = isWide ? 800 : 400;
 		screen_h = 240;
 		break;
 	default:
@@ -487,6 +494,7 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 		screen_h = 512;
 		break;
 	}
+	int wide = isWide ? 2 : 1;
 
 	unsigned corew, coreh;
 	core->desiredVideoDimensions(core, &corew, &coreh);
@@ -497,24 +505,16 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 		w = GB_VIDEO_HORIZONTAL_PIXELS;
 		h = GB_VIDEO_VERTICAL_PIXELS;
 	}
-	int innerw = w;
-	int innerh = h;
-	// Get greatest common divisor
-	while (w != 0) {
-		int temp = h % w;
-		h = w;
-		w = temp;
-	}
-	int gcd = h;
-	unsigned aspectw = innerw / gcd;
-	unsigned aspecth = innerh / gcd;
+	int aspectw = w;
+	int aspecth = h;
+	int gcd = reduceFraction(&aspecth, &aspectw);
 	int x = 0;
 	int y = 0;
 
 	switch (screenMode) {
 	case SM_PA_TOP:
 	case SM_PA_BOTTOM:
-		w = corew;
+		w = corew * wide;
 		h = coreh;
 		x = (screen_w - w) / 2;
 		y = (screen_h - h) / 2;
@@ -544,8 +544,8 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 	}
 	ctrFlushBatch();
 
-	innerw = corew;
-	innerh = coreh;
+	int innerw = corew;
+	int innerh = coreh;
 	corew = w;
 	coreh = h;
 	screen_h = 240;
@@ -554,7 +554,7 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 		screen_w = 320;
 	} else {
 		C3D_FrameDrawOn(topScreen[doubleBuffer]);
-		screen_w = 400;
+		screen_w = isWide ? 800 : 400;
 	}
 	ctrSetViewportSize(screen_w, screen_h, true);
 
@@ -566,6 +566,7 @@ static void _drawTex(struct mCore* core, bool faded, bool both) {
 	case SM_AF_BOTTOM:
 		afw = screen_w / (float) aspectw;
 		afh = screen_h / (float) aspecth;
+		innerw *= wide;
 		if (afw * aspecth > screen_h) {
 			w = innerw * afh / gcd;
 			h = innerh * afh / gcd;
@@ -846,6 +847,12 @@ int main() {
 
 	gfxInit(GSP_BGR8_OES, GSP_BGR8_OES, true);
 
+	u8 model = 0;
+	CFGU_GetSystemModel(&model);
+	if (model != 3 /* o2DS */) {
+		gfxSetWide(true);
+	}
+
 	if (!_initGpu()) {
 		outputTexture[0].data = 0;
 		_cleanup();