From caa956d120b34e4c0deadb9e61af509a88debd09 Mon Sep 17 00:00:00 2001
From: neonloop
Date: Fri, 25 Mar 2022 21:34:32 +0000
Subject: Skips main loop fb flip when screen is skipped

If core hasn't updated screen, no need to flip. Can save vsync delay,
makes ff faster
---
 plat_sdl.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/plat_sdl.c b/plat_sdl.c
index 5d996b3..0beb924 100644
--- a/plat_sdl.c
+++ b/plat_sdl.c
@@ -29,6 +29,8 @@ static char msg[HUD_LEN];
 static unsigned msg_priority = 0;
 static unsigned msg_expire = 0;
 
+static bool frame_dirty = false;
+
 static void video_expire_msg(void)
 {
 	msg[0] = '\0';
@@ -209,6 +211,7 @@ void plat_video_set_msg(const char *new_msg, unsigned priority, unsigned msec)
 
 void plat_video_process(const void *data, unsigned width, unsigned height, size_t pitch) {
 	static int had_msg = 0;
+	frame_dirty = true;
 	SDL_LockSurface(screen);
 
 	if (had_msg) {
@@ -230,7 +233,10 @@ void plat_video_process(const void *data, unsigned width, unsigned height, size_
 
 void plat_video_flip(void)
 {
-	fb_flip();
+	if (frame_dirty)
+		fb_flip();
+
+	frame_dirty = false;
 }
 
 void plat_video_close(void)
-- 
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