From 2dec4d0a11aca1cb7b045f7c7475fd55c99cc6a9 Mon Sep 17 00:00:00 2001
From: Peter Veenstra <qbix79@users.sourceforge.net>
Date: Fri, 7 Feb 2020 15:39:21 +0000
Subject: [PATCH] Limit max software scaler line limit to a 4k monitor.
 (relevant for people who use larger scalers)

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4316
---
 src/gui/render.cpp         |  9 +++++++++
 src/gui/render_scalers.cpp |  6 +++---
 src/gui/render_scalers.h   | 15 ++++++++++++---
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/gui/render.cpp b/src/gui/render.cpp
index 6db94cfe..39596c70 100644
--- a/src/gui/render.cpp
+++ b/src/gui/render.cpp
@@ -281,6 +281,11 @@ static void RENDER_Reset( void ) {
 		gfx_scalew = 1;
 		gfx_scaleh = 1;
 	}
+
+	/* Don't do software scaler sizes larger than 4k */
+	Bitu maxsize_current_input = SCALER_MAXLINE_WIDTH/width;
+	if (render.scale.size > maxsize_current_input) render.scale.size = maxsize_current_input;
+
 	if ((dblh && dblw) || (render.scale.forced && !dblh && !dblw)) {
 		/* Initialize always working defaults */
 		if (render.scale.size == 2)
@@ -348,6 +353,10 @@ static void RENDER_Reset( void ) {
 #endif
 	} else if (dblw) {
 		simpleBlock = &ScaleNormalDw;
+		if (width * simpleBlock->xscale > SCALER_MAXLINE_WIDTH) {
+			// This should only happen if you pick really bad values... but might be worth adding selecting a scaler that fits
+			simpleBlock = &ScaleNormal1x;
+		}
 	} else if (dblh) {
 		simpleBlock = &ScaleNormalDh;
 	} else  {
diff --git a/src/gui/render_scalers.cpp b/src/gui/render_scalers.cpp
index caa04c65..1abf56d4 100644
--- a/src/gui/render_scalers.cpp
+++ b/src/gui/render_scalers.cpp
@@ -31,9 +31,9 @@ Bitu Scaler_ChangedLineIndex;
 
 static union {
 	 //The +1 is a at least for the normal scalers not needed. (-1 is enough)
-	Bit32u b32 [SCALER_MAX_MUL_HEIGHT+1][SCALER_MAXWIDTH*SCALER_MAX_MUL_WIDTH];
-	Bit16u b16 [SCALER_MAX_MUL_HEIGHT+1][SCALER_MAXWIDTH*SCALER_MAX_MUL_WIDTH];
-	Bit8u b8 [SCALER_MAX_MUL_HEIGHT+1][SCALER_MAXWIDTH*SCALER_MAX_MUL_WIDTH];
+	Bit32u b32 [SCALER_MAX_MUL_HEIGHT + 1][SCALER_MAXLINE_WIDTH];
+	Bit16u b16 [SCALER_MAX_MUL_HEIGHT + 1][SCALER_MAXLINE_WIDTH];
+	Bit8u   b8 [SCALER_MAX_MUL_HEIGHT + 1][SCALER_MAXLINE_WIDTH];
 } scalerWriteCache;
 //scalerFrameCache_t scalerFrameCache;
 scalerSourceCache_t scalerSourceCache;
diff --git a/src/gui/render_scalers.h b/src/gui/render_scalers.h
index 0fb6a0c0..d2efa2c8 100644
--- a/src/gui/render_scalers.h
+++ b/src/gui/render_scalers.h
@@ -26,16 +26,25 @@
 #define SCALER_MAX_MUL_HEIGHT 3
 
 #if RENDER_USE_ADVANCED_SCALERS>0
-#define SCALER_MAXWIDTH		1280 
+#define SCALER_MAXWIDTH 	1280 
 #define SCALER_MAXHEIGHT	1024
+#define SCALER_MAXX     	4096
 #else
 // reduced to save some memory
-#define SCALER_MAXWIDTH		800 
+#define SCALER_MAXWIDTH 	800 
 #define SCALER_MAXHEIGHT	600
+#define SCALER_MAXX     	2048
 #endif
 
+#if (SCALER_MAX_MUL_WIDTH * SCALER_MAXWIDTH) > SCALER_MAXX
+#define SCALER_MAXLINE_WIDTH SCALER_MAXX
+#else 
+#define SCALER_MAXLINE_WIDTH (SCALER_MAX_MUL_WIDTH * SCALER_MAXWIDTH)
+#endif
+
+
 #if RENDER_USE_ADVANCED_SCALERS>1
-#define SCALER_COMPLEXWIDTH		800
+#define SCALER_COMPLEXWIDTH 	800
 #define SCALER_COMPLEXHEIGHT	600
 #endif