From 43c5417e5098ce5a6b8de87e31beeb1a30dd1556 Mon Sep 17 00:00:00 2001
From: Patrice Mandin <patmandin@gmail.com>
Date: Sat, 12 Jan 2019 23:07:14 +0100
Subject: [PATCH] atari:xbios: On ST,STE, C2P routine has 4 bits planes as
 destination, calculate correct width

---
 src/video/xbios/SDL_xbios_st.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/video/xbios/SDL_xbios_st.c b/src/video/xbios/SDL_xbios_st.c
index 65ab8a3a5..e56ed6cca 100644
--- a/src/video/xbios/SDL_xbios_st.c
+++ b/src/video/xbios/SDL_xbios_st.c
@@ -158,6 +158,10 @@ static void getScreenFormat(_THIS, int bpp, Uint32 *rmask, Uint32 *gmask, Uint32
 
 static int getLineWidth(_THIS, xbiosmode_t *new_video_mode, int width, int bpp)
 {
+	if (bpp==4) {
+		return (width >> 1);
+	}
+
 	return (width * (((bpp==15) ? 16 : bpp)>>3));
 }