text: /***************************************************************************
  
      Atari "Round" hardware
  
  ****************************************************************************/
  
  #include "driver.h"
  #include "machine/atarigen.h"
  #include "relief.h"
  
  
  
  /*************************************
   *
   *  Tilemap callbacks
   *
   *************************************/
  
  static TILE_GET_INFO( get_playfield_tile_info )
  {
  	UINT16 data1 = atarigen_playfield[tile_index];
  	UINT16 data2 = atarigen_playfield_upper[tile_index] & 0xff;
  	int code = data1 & 0x7fff;
  	int color = 0x20 + (data2 & 0x0f);
  	SET_TILE_INFO(0, code, color, (data1 >> 15) & 1);
  }
  
  
  static TILE_GET_INFO( get_playfield2_tile_info )
  {
  	UINT16 data1 = atarigen_playfield2[tile_index];
  	UINT16 data2 = atarigen_playfield_upper[tile_index] >> 8;
  	int code = data1 & 0x7fff;
  	int color = data2 & 0x0f;
  	SET_TILE_INFO(0, code, color, (data1 >> 15) & 1);
  }
  
  
  
  /*************************************
   *
   *  Video system start
   *
   *************************************/
  
  VIDEO_START( relief )
  {
  	static const atarimo_desc modesc =
  	{
  		1,					/* index to which gfx system */
  		1,					/* number of motion object banks */
  		1,					/* are the entries linked? */
  		0,					/* are the entries split? */
  		0,					/* render in reverse order? */
  		0,					/* render in swapped X/Y order? */
  		0,					/* does the neighbor bit affect the next object? */
  		8,					/* pixels per SLIP entry (0 for no-slip) */
  		0,					/* pixel offset for SLIPs */
  		0,					/* maximum number of links to visit/scanline (0=all) */
  
  		0x100,				/* base palette entry */
  		0x100,				/* maximum number of colors */
  		0,					/* transparent pen index */
  
  		{{ 0x00ff,0,0,0 }},	/* mask for the link */
  		{{ 0 }},			/* mask for the graphics bank */
  		{{ 0,0x7fff,0,0 }},	/* mask for the code index */
  		{{ 0 }},			/* mask for the upper code index */
  		{{ 0,0,0x000f,0 }},	/* mask for the color */
  		{{ 0,0,0xff80,0 }},	/* mask for the X position */
  		{{ 0,0,0,0xff80 }},	/* mask for the Y position */
  		{{ 0,0,0,0x0070 }},	/* mask for the width, in tiles*/
  		{{ 0,0,0,0x0007 }},	/* mask for the height, in tiles */
  		{{ 0,0x8000,0,0 }},	/* mask for the horizontal flip */
  		{{ 0 }},			/* mask for the vertical flip */
  		{{ 0 }},			/* mask for the priority */
  		{{ 0 }},			/* mask for the neighbor */
  		{{ 0 }},			/* mask for absolute coordinates */
  
  		{{ 0 }},			/* mask for the special value */
  		0,					/* resulting value to indicate "special" */
  		0					/* callback routine for special entries */
  	};
  
  	/* MOs are 5bpp but with a 4-bit color granularity */
  	machine->gfx[1]->color_granularity = 16;
  
  	/* initialize the playfield */
  	atarigen_playfield_tilemap = tilemap_create(machine, get_playfield_tile_info, tilemap_scan_cols,  8,8, 64,64);
  
  	/* initialize the second playfield */
  	atarigen_playfield2_tilemap = tilemap_create(machine, get_playfield2_tile_info, tilemap_scan_cols,  8,8, 64,64);
  	tilemap_set_transparent_pen(atarigen_playfield2_tilemap, 0);
  
  	/* initialize the motion objects */
  	atarimo_init(machine, 0, &modesc);
  }
  
  
  
  /*************************************
   *
   *  Main refresh
   *
   *************************************/
  
  VIDEO_UPDATE( relief )
  {
  	bitmap_t *priority_bitmap = screen->machine->priority_bitmap;
  	atarimo_rect_list rectlist;
  	bitmap_t *mobitmap;
  	int x, y, r;
  
  	/* draw the playfield */
  	bitmap_fill(priority_bitmap, cliprect, 0);
  	tilemap_draw(bitmap, cliprect, atarigen_playfield_tilemap, 0, 0);
  	tilemap_draw(bitmap, cliprect, atarigen_playfield2_tilemap, 0, 1);
  
  	/* draw and merge the MO */
  	mobitmap = atarimo_render(0, cliprect, &rectlist);
  	for (r = 0; r < rectlist.numrects; r++, rectlist.rect++)
  		for (y = rectlist.rect->min_y; y <= rectlist.rect->max_y; y++)
  		{
  			UINT16 *mo = (UINT16 *)mobitmap->base + mobitmap->rowpixels * y;
  			UINT16 *pf = (UINT16 *)bitmap->base + bitmap->rowpixels * y;
  			UINT8 *pri = (UINT8 *)priority_bitmap->base + priority_bitmap->rowpixels * y;
  			for (x = rectlist.rect->min_x; x <= rectlist.rect->max_x; x++)
  				if (mo[x])
  				{
  					/* verified from the GALs on the real PCB; equations follow
                       *
                       *      --- PF/M is 1 if playfield has priority, or 0 if MOs have priority
                       *      PF/M = PFXS
                       *
                       *      --- CS0 is set to 1 if the MO is transparent
                       *      CS0=!MPX0*!MPX1*!MPX2*!MPX3
                       *
                       *      --- CS1 is 1 to select playfield pixels or 0 to select MO pixels
                       *      !CS1=MPX5*MPX6*MPX7*!CS0
                       *          +!MPX4*MPX5*MPX6*MPX7
                       *          +PFXS*!CS0
                       *          +!MPX4*PFXS
                       *
                       *      --- CRA10 is the 0x200 bit of the color RAM index; set for the top playfield only
                       *      CRA10:=CS1*PFXS
                       *
                       *      --- CRA9 is the 0x100 bit of the color RAM index; set for MOs only
                       *      !CA9:=CS1
                       *
                       *      --- CRA8-1 are the low 8 bits of the color RAM index; set as expected
                       */
  					int cs0 = 0;
  					int cs1 = 1;
  
  					/* compute the CS0 signal */
  					cs0 = ((mo[x] & 0x0f) == 0);
  
  					/* compute the CS1 signal */
  					if ((!cs0 && (mo[x] & 0xe0) == 0xe0) ||
  						((mo[x] & 0xf0) == 0xe0) ||
  						(!pri[x] && !cs0) ||
  						(!pri[x] && !(mo[x] & 0x10)))
  						cs1 = 0;
  
  					/* MO is displayed if cs1 == 0 */
  					if (!cs1)
  						pf[x] = mo[x];
  
  					/* erase behind ourselves */
  					mo[x] = 0;
  				}
  		}
  	return 0;
  }
  