text: /***************************************************************************
  
  	vidhrdw.c
  
  	Functions to emulate the video hardware of the machine.
  
  	There are only a few differences between the video hardware of Mysterious
  	Stones and Mat Mania. The tile bank select bit is different and the sprite
  	selection seems to be different as well. Additionally, the palette is stored
  	differently. I'm also not sure that the 2nd tile page is really used in
  	Mysterious Stones.
  
  ***************************************************************************/
  
  #include "driver.h"
  #include "vidhrdw/generic.h"
  
  
  UINT8 *mystston_videoram2;
  
  static int mystston_fgcolor, mystston_bgpage;
  
  static struct tilemap *fg_tilemap, *bg_tilemap;
  
  /***************************************************************************
  
    Convert the color PROMs into a more useable format.
  
    Mysterious Stones has both palette RAM and a PROM. The PROM is used for
    text.
  
  ***************************************************************************/
  
  PALETTE_INIT( mystston )
  {
  	int i;
  
  	for (i = 0; i < 32; i++)
  	{
  		int bit0, bit1, bit2, r, g, b;
  
  		/* red component*/
  
  		bit0 = (*color_prom >> 0) & 0x01;
  		bit1 = (*color_prom >> 1) & 0x01;
  		bit2 = (*color_prom >> 2) & 0x01;
  
  		r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
  
  		/* green component*/
  
  		bit0 = (*color_prom >> 3) & 0x01;
  		bit1 = (*color_prom >> 4) & 0x01;
  		bit2 = (*color_prom >> 5) & 0x01;
  
  		g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
  
  		/* blue component*/
  
  		bit0 = 0;
  		bit1 = (*color_prom >> 6) & 0x01;
  		bit2 = (*color_prom >> 7) & 0x01;
  
  		b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
  
  		palette_set_color(i + 24, r, g, b);	/* first 24 colors are from RAM*/
  
  		color_prom++;
  	}
  }
  
  WRITE_HANDLER( mystston_videoram_w )
  {
  	if (videoram[offset] != data)
  	{
  		videoram[offset] = data;
  		tilemap_mark_tile_dirty(fg_tilemap, offset & 0x3ff);
  	}
  }
  
  WRITE_HANDLER( mystston_videoram2_w )
  {
  	if (videoram[offset] != data)
  	{
  		mystston_videoram2[offset] = data;
  		tilemap_mark_tile_dirty(bg_tilemap, offset & 0x1ff);
  	}
  }
  
  WRITE_HANDLER( mystston_scroll_w )
  {
  	tilemap_set_scrolly(bg_tilemap, 0, data);
  }
  
  WRITE_HANDLER( mystston_control_w )
  {
  	/* bits 0 and 1 are foreground text color*/
  	if (mystston_fgcolor != ((data & 0x01) << 1) + ((data & 0x02) >> 1))
  	{
  		mystston_fgcolor = ((data & 0x01) << 1) + ((data & 0x02) >> 1);
  		tilemap_mark_all_tiles_dirty(fg_tilemap);
  	}
  
  	/* bit 2 is background page select*/
  	mystston_bgpage = (data & 0x04) ? 1:0;
  
  	/* bits 4 and 5 are coin counters in flipped order*/
  	coin_counter_w(0, data & 0x20);
  	coin_counter_w(1, data & 0x10);
  
  	/* bit 7 is screen flip*/
  	flip_screen_set((data & 0x80) ^ ((readinputport(3) & 0x20) ? 0x80:0));
  }
  
  static void get_bg_tile_info(int tile_index)
  {
  	int code = mystston_videoram2[tile_index] + ((mystston_videoram2[tile_index + 0x200] & 0x01) << 8);
  	int flags = (tile_index & 0x10) ? TILE_FLIPY : 0;
  
  	SET_TILE_INFO(1, code, 0, flags)
  }
  
  static void get_fg_tile_info(int tile_index)
  {
  	int code = videoram[tile_index] + ((videoram[tile_index + 0x400] & 0x07) << 8);
  	int color = mystston_fgcolor;
  	
  	SET_TILE_INFO(0, code, color, 0)
  }
  
  VIDEO_START( mystston )
  {
  	bg_tilemap = tilemap_create(get_bg_tile_info, tilemap_scan_cols_flip_x, 
  		TILEMAP_OPAQUE, 16, 16, 16, 32);
  
  	if ( !bg_tilemap )
  		return 1;
  
  	fg_tilemap = tilemap_create(get_fg_tile_info, tilemap_scan_cols_flip_x, 
  		TILEMAP_TRANSPARENT, 8, 8, 32, 32);
  
  	if ( !fg_tilemap )
  		return 1;
  
  	tilemap_set_transparent_pen(fg_tilemap, 0);
  
  	return 0;
  }
  
  static void draw_sprites( struct mame_bitmap *bitmap, const struct rectangle *cliprect )
  {
  	int offs;
  
  	for (offs = 0; offs < spriteram_size; offs += 4)
  	{
  		int attr = spriteram[offs];
  
  		if (attr & 0x01)
  		{
  			int code = spriteram[offs + 1] + ((attr & 0x10) << 4);
  			int color = (attr & 0x08) >> 3;
  			int flipx = attr & 0x04;
  			int flipy = attr & 0x02;
  			int sx = 240 - spriteram[offs + 3];
  			int sy = (240 - spriteram[offs + 2]) & 0xff;
  
  			if (flip_screen)
  			{
  				sx = 240 - sx;
  				sy = 240 - sy;
  				flipx = !flipx;
  				flipy = !flipy;
  			}
  
  			drawgfx(bitmap,Machine->gfx[2],	code, color, flipx, flipy,
  				sx, sy, cliprect, TRANSPARENCY_PEN, 0);
  		}
  	}
  }
  
  VIDEO_UPDATE( mystston )
  {
  	tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0);
  	draw_sprites(bitmap, cliprect);
  	tilemap_draw(bitmap, cliprect, fg_tilemap, 0, 0);
  }
  