Function updateVideoScannerAddress

source/NTSC.cpp:748–804

===========================================================================

//===========================================================================
inline void updateVideoScannerAddress()
{
	if (g_nVideoMixed && GetVideo().GetVideoRefreshRate() == VR_50HZ)	// GH#763
	{
		if (g_nVideoClockVert >= VIDEO_SCANNER_Y_MIXED)
			g_nColorBurstPixels = 0;	// instantaneously kill color-burst!
		else if (g_nVideoClockVert == 0 && (GetVideo().GetVideoMode() & VF_TEXT) == 0)
			g_nColorBurstPixels = 1024;	// setup for line-0 (when TEXT is off), ie. so GetColorBurst() returns true below (GH#1119)
	}

	if (g_pFuncUpdateGraphicsScreen == updateScreenSHR)
	{
		g_pVideoAddress = g_nVideoClockVert < VIDEO_SCANNER_Y_DISPLAY_IIGS ? g_pScanLines[2 * g_nVideoClockVert] : g_pScanLines[0];
		return;
	}

	g_pVideoAddress = g_nVideoClockVert < VIDEO_SCANNER_Y_DISPLAY ? g_pScanLines[2 * g_nVideoClockVert] : g_pScanLines[0];

	// Adjust, as these video styles have 2x 14M pixels of pre-render
	// NB. For VT_COLOR_MONITOR_NTSC, also check color-burst so that TEXT and MIXED(HGR+TEXT) render the TEXT at the same offset (GH#341)
	if (GetVideo().GetVideoType() == VT_MONO_TV || GetVideo().GetVideoType() == VT_COLOR_TV || (GetVideo().GetVideoType() == VT_COLOR_MONITOR_NTSC && GetColorBurst()))
		g_pVideoAddress -= 2;

	// GH#555: For the 14M video modes (DHGR,DGR,80COL), start rendering 1x 14M pixel early to account for these video modes being shifted right by 1 pixel
	// NB. This 1 pixel shift right is a workaround for the 14M video modes that actually start 7x 14M pixels to the left on *real h/w*.
	// . 7x 14M pixels early + 1x 14M pixel shifted right = 2 complete color phase rotations.
	// . ie. the 14M colors are correct, but being 1 pixel out is the closest we can get the 7M and 14M video modes to overlap.
	// . The alternative is to render the 14M correctly 7 pixels early, but have 7-pixel borders left (for 7M modes) or right (for 14M modes).
	if (((g_pFuncUpdateGraphicsScreen == updateScreenDoubleHires80) ||
		(g_pFuncUpdateGraphicsScreen == updateScreenDoubleLores80) ||
		(g_pFuncUpdateGraphicsScreen == updateScreenText80) ||
		(g_pFuncUpdateGraphicsScreen == updateScreenText80RGB) ||
		(g_nVideoMixed && g_nVideoClockVert >= VIDEO_SCANNER_Y_MIXED && (g_pFuncUpdateTextScreen == updateScreenText80 || g_pFuncUpdateGraphicsScreen == updateScreenText80RGB)))
		&& (GetVideo().GetVideoType() != VT_COLOR_IDEALIZED) && (GetVideo().GetVideoType() != VT_COLOR_VIDEOCARD_RGB))	// Fix for "Ansi Story" (Turn the disk over) - Top row of TEXT80 is shifted by 1 pixel
	{
		g_pVideoAddress -= 1;
	}

	// Centre the older //e video modes when running with a VidHD
	g_pVideoAddress += GetVideo().GetFrameBufferCentringValue();

	if (GetVideo().HasVidHD())
	{
		if (GetVideo().GetVideoType() == VT_COLOR_MONITOR_NTSC)
		{
			// EG. Switching between TEXT (full 24 lines) and MIXED (HGR with purple vertical line-0)
			// - AppleWin-Test repo, Tests-Various.dsk, option-C
			g_pVideoAddress -= 2;
			*(uint32_t*)g_pVideoAddress++ = 0 | ALPHA32_MASK;
			*(uint32_t*)g_pVideoAddress++ = 0 | ALPHA32_MASK;
		}
	}

	g_nColorPhaseNTSC      = INITIAL_COLOR_PHASE;
	g_nLastColumnPixelNTSC = 0;
	g_nSignalBitsNTSC      = 0;
}