From a304c4170664d4f8da197da1b278ce28767c1a30 Mon Sep 17 00:00:00 2001
From: Alberto Mardegan <mardy@users.sourceforge.net>
Date: Sun, 14 Jan 2024 11:23:05 +0300
Subject: [PATCH] ogc: implement double-buffering

---
 src/video/ogc/SDL_ogcvideo.c | 8 ++++++--
 src/video/ogc/SDL_ogcvideo.h | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/video/ogc/SDL_ogcvideo.c b/src/video/ogc/SDL_ogcvideo.c
index 28e0cccb1b5ce..b86da4ec633a5 100644
--- a/src/video/ogc/SDL_ogcvideo.c
+++ b/src/video/ogc/SDL_ogcvideo.c
@@ -108,7 +108,7 @@ int OGC_VideoInit(_THIS)
 
     /* Allocate the XFB */
     videodata->xfb[0] = MEM_K0_TO_K1(SYS_AllocateFramebuffer(vmode));
-    videodata->xfb[1] = NULL; /* We'll allocate this when double-buffering */
+    videodata->xfb[1] = MEM_K0_TO_K1(SYS_AllocateFramebuffer(vmode));
 
     VIDEO_ClearFrameBuffer(vmode, videodata->xfb[0], COLOR_BLACK);
     VIDEO_SetNextFramebuffer(videodata->xfb[0]);
@@ -172,20 +172,24 @@ void OGC_VideoQuit(_THIS)
 void *OGC_video_get_xfb(_THIS)
 {
     SDL_VideoData *videodata = _this->driverdata;
-    return videodata->xfb[0];
+    return videodata->xfb[videodata->fb_index];
 }
 
 void OGC_video_flip(_THIS, bool vsync)
 {
+    SDL_VideoData *videodata = _this->driverdata;
     void *xfb = OGC_video_get_xfb(_this);
     GX_CopyDisp(xfb, GX_TRUE);
     GX_DrawDone();
     GX_Flush();
 
+    VIDEO_SetNextFramebuffer(xfb);
     VIDEO_Flush();
     if (vsync) {
         VIDEO_WaitVSync();
     }
+
+    videodata->fb_index ^= 1;
 }
 
 #endif /* SDL_VIDEO_DRIVER_OGC */
diff --git a/src/video/ogc/SDL_ogcvideo.h b/src/video/ogc/SDL_ogcvideo.h
index 193d94e82f377..3821d1966c085 100644
--- a/src/video/ogc/SDL_ogcvideo.h
+++ b/src/video/ogc/SDL_ogcvideo.h
@@ -32,6 +32,7 @@ typedef struct SDL_VideoData
     GXRModeObj *vmode;
     u8 *gp_fifo;
     void *xfb[2];
+    u8 fb_index;
 } SDL_VideoData;
 
 typedef struct SDL_WindowData