Fixed occasional flicker when changing video mode with F9. (Fixes AppleWin#611)

Author: tomcw

source/Frame.cpp

@@ -1295,7 +1295,8 @@ LRESULT CALLBACK FrameWndProc (
 			// TODO: Clean up code:FrameRefreshStatus(DRAW_TITLE) DrawStatusArea((HDC)0,DRAW_TITLE)
 			DrawStatusArea( (HDC)0, DRAW_TITLE );
 
-			VideoReinitialize();
+			VideoReinitialize(false);
+
 			if (g_nAppMode != MODE_LOGO)
 			{
 				if (g_nAppMode == MODE_DEBUG)

source/NTSC.cpp

@@ -2120,14 +2120,15 @@ void NTSC_VideoInit( uint8_t* pFramebuffer ) // wsVideoInit
 }
 
 //===========================================================================
-void NTSC_VideoReinitialize( DWORD cyclesThisFrame )
+void NTSC_VideoReinitialize( DWORD cyclesThisFrame, bool bInitVideoScannerAddress )
 {
 	_ASSERT(cyclesThisFrame < VIDEO_SCANNER_6502_CYCLES);
 	if (cyclesThisFrame >= VIDEO_SCANNER_6502_CYCLES) cyclesThisFrame = 0;	// error
 	g_nVideoClockVert = (uint16_t) (cyclesThisFrame / VIDEO_SCANNER_MAX_HORZ);
 	g_nVideoClockHorz = cyclesThisFrame % VIDEO_SCANNER_MAX_HORZ;
 
-	updateVideoScannerAddress();	// Pre-condition: g_nVideoClockVert
+	if (bInitVideoScannerAddress)		// GH#611
+		updateVideoScannerAddress();	// Pre-condition: g_nVideoClockVert
 }
 
 //===========================================================================

source/NTSC.h

@@ -11,7 +11,7 @@
 	extern void     NTSC_VideoClockResync( const DWORD dwCyclesThisFrame );
 	extern uint16_t NTSC_VideoGetScannerAddress( const ULONG uExecutedCycles );
 	extern void     NTSC_VideoInit( uint8_t *pFramebuffer );
-	extern void     NTSC_VideoReinitialize( DWORD cyclesThisFrame );
+	extern void     NTSC_VideoReinitialize( DWORD cyclesThisFrame, bool bInitVideoScannerAddress );
 	extern void     NTSC_VideoInitAppleType();
 	extern void     NTSC_VideoInitChroma();
 	extern void     NTSC_VideoUpdateCycles( long cycles6502 );

source/Video.cpp

@@ -625,9 +625,9 @@ void VideoRefreshScreen ( uint32_t uRedrawWholeScreenVideoMode /* =0*/, bool bRe
 }
 
 //===========================================================================
-void VideoReinitialize ()
+void VideoReinitialize (bool bInitVideoScannerAddress /*= true*/)
 {
-	NTSC_VideoReinitialize( g_dwCyclesThisFrame );
+	NTSC_VideoReinitialize( g_dwCyclesThisFrame, bInitVideoScannerAddress );
 	NTSC_VideoInitAppleType();
 	NTSC_SetVideoStyle();
 	NTSC_SetVideoTextMode( g_uVideoMode &  VF_80COL ? 80 : 40 );

source/Video.h

@@ -177,7 +177,7 @@ void    VideoRedrawScreenDuringFullSpeed(DWORD dwCyclesThisFrame, bool bInit = f
 void    VideoRedrawScreenAfterFullSpeed(DWORD dwCyclesThisFrame);
 void    VideoRedrawScreen (void);
 void    VideoRefreshScreen (uint32_t uRedrawWholeScreenVideoMode = 0, bool bRedrawWholeScreen = false);
-void    VideoReinitialize ();
+void    VideoReinitialize (bool bInitVideoScannerAddress = true);
 void    VideoResetState ();
 enum VideoScanner_e {VS_FullAddr, VS_PartialAddrV, VS_PartialAddrH};
 WORD    VideoGetScannerAddress(DWORD nCycles, VideoScanner_e videoScannerAddr = VS_FullAddr);