/*********************************************************************

	video/apple2gs.c

	Apple IIgs video code

*********************************************************************/

#include "mame.h"
#include "includes/apple2.h"
#include "includes/apple2gs.h"

static mame_bitmap *apple2gs_legacy_gfx;
UINT16 apple2gs_bordercolor;

VIDEO_START( apple2gs )
{
	apple2gs_bordercolor = 0;
	apple2_video_start(apple2gs_slowmem, 0x20000, 0, 8);
	apple2gs_legacy_gfx = auto_bitmap_alloc(560, 192, BITMAP_FORMAT_INDEXED16);
}



VIDEO_UPDATE( apple2gs )
{
	const UINT8 *vram;
	UINT16 *scanline;
	UINT8 scb, b;
	int col, palette;
	UINT16 last_pixel = 0, pixel;
	int beamy;

	beamy = cliprect->min_y;

	// HACK: for some reason, we skip scanline 1.  make up for it.
	if (beamy == 0)
	{
		rectangle new_cliprect;

		new_cliprect.min_x = cliprect->min_x;
		new_cliprect.max_x = cliprect->max_x;
		new_cliprect.min_y = cliprect->min_y+1;
		new_cliprect.max_y = cliprect->min_y+1;

		video_update_apple2gs(machine, screen, bitmap, &new_cliprect);
	}

	if (apple2gs_newvideo & 0x80)
	{
		// in top or bottom border?
		if ((beamy < BORDER_TOP) || (beamy >= 200+BORDER_TOP))
		{
			// don't draw past the bottom border
			if (beamy >= 231+BORDER_TOP) 
			{
				return 0;
			}

			scanline = BITMAP_ADDR16(bitmap, beamy, 0);
			for (col = 0; col < BORDER_LEFT+BORDER_RIGHT+640; col++)
			{
				scanline[col] = apple2gs_bordercolor;
			}
		}
		else	// regular screen area
		{
			int shrline = beamy - BORDER_TOP;

			scb = apple2gs_slowmem[0x19D00 + shrline];
			palette = ((scb & 0x0f) << 4) + 16;

			vram = &apple2gs_slowmem[0x12000 + (shrline * 160)];
			scanline = BITMAP_ADDR16(bitmap, beamy, 0);

			// draw left and right borders
			for (col = 0; col < BORDER_LEFT; col++)
			{
				scanline[col] = apple2gs_bordercolor;
				scanline[col+BORDER_LEFT+640] = apple2gs_bordercolor;
			}

			if (scb & 0x80)	// 640 mode
			{
				for (col = 0; col < 160; col++)
				{
					b = vram[col];
					scanline[col * 4 + 0 + BORDER_LEFT] = palette +  0 + ((b >> 6) & 0x03);
					scanline[col * 4 + 1 + BORDER_LEFT] = palette +  4 + ((b >> 4) & 0x03);
					scanline[col * 4 + 2 + BORDER_LEFT] = palette +  8 + ((b >> 2) & 0x03);
					scanline[col * 4 + 3 + BORDER_LEFT] = palette + 12 + ((b >> 0) & 0x03);
				}
			}
			else		// 320 mode
			{
				for (col = 0; col < 160; col++)
				{
					b = vram[col];
					pixel = (b >> 4) & 0x0f;

					if ((scb & 0x20) && !pixel)
						pixel = last_pixel;
					else
						last_pixel = pixel;
					pixel += palette;
					scanline[col * 4 + 0 + BORDER_LEFT] = pixel;
					scanline[col * 4 + 1 + BORDER_LEFT] = pixel;

					b = vram[col];
					pixel = (b >> 0) & 0x0f;

					if ((scb & 0x20) && !pixel)
						pixel = last_pixel;
					else
						last_pixel = pixel;
					pixel += palette;
					scanline[col * 4 + 2 + BORDER_LEFT] = pixel;
					scanline[col * 4 + 3 + BORDER_LEFT] = pixel;
				}
			}
		}		
	}
	else
	{
		/* call legacy Apple II video rendering at scanline 0 to draw into the off-screen buffer */
		if (beamy == 0)
		{
			rectangle new_cliprect;

			new_cliprect.min_x = 0;
			new_cliprect.min_y = 0;
			new_cliprect.max_x = 559;
			new_cliprect.max_y = 191;
			video_update_apple2(machine, screen, apple2gs_legacy_gfx, &new_cliprect);
		}

		if ((beamy < (BORDER_TOP+4)) || (beamy >= (192+4+BORDER_TOP)))
		{
			if (beamy >= (231+BORDER_TOP))
			{
				return 0;
			}

			scanline = BITMAP_ADDR16(bitmap, beamy, 0);
			for (col = 0; col < BORDER_LEFT+BORDER_RIGHT+640; col++)
			{
				scanline[col] = apple2gs_bordercolor;
			}
		}
		else
		{
			scanline = BITMAP_ADDR16(bitmap, beamy, 0);

			// draw left and right borders
			for (col = 0; col < BORDER_LEFT + 40; col++)
			{
				scanline[col] = apple2gs_bordercolor;
				scanline[col+BORDER_LEFT+600] = apple2gs_bordercolor;
			}

			memcpy(scanline + 40 + BORDER_LEFT, BITMAP_ADDR16(apple2gs_legacy_gfx, beamy-(BORDER_TOP+4), 0), 560 * sizeof(UINT16));
		}
	}
	return 0;
}