text: /***************************************************************************
  
    video.c
  
    Functions to emulate the video hardware of the machine.
  
  ***************************************************************************/
  
  #include "emu.h"
  #include "video/resnet.h"
  #include "includes/trackfld.h"
  
  /***************************************************************************
  
    Convert the color PROMs into a more useable format.
  
    Super Basketball has three 256x4 palette PROMs (one per gun) and two 256x4
    lookup table PROMs (one for characters, one for sprites).
    I don't know for sure how the palette PROMs are connected to the RGB
    output, but it's probably the usual:
  
    bit 3 -- 220 ohm resistor  -- RED/GREEN/BLUE
          -- 470 ohm resistor  -- RED/GREEN/BLUE
          -- 1  kohm resistor  -- RED/GREEN/BLUE
    bit 0 -- 2.2kohm resistor  -- RED/GREEN/BLUE
  
  ***************************************************************************/
  
  PALETTE_INIT( sbasketb )
  {
  	static const int resistances[4] = { 2000, 1000, 470, 220 };
  	double rweights[4], gweights[4], bweights[4];
  	int i;
  
  	/* compute the color output resistor weights */
  	compute_resistor_weights(0,	255, -1.0,
  			4, resistances, rweights, 1000, 0,
  			4, resistances, gweights, 1000, 0,
  			4, resistances, bweights, 1000, 0);
  
  	/* allocate the colortable */
  	machine->colortable = colortable_alloc(machine, 0x100);
  
  	/* create a lookup table for the palette */
  	for (i = 0; i < 0x100; i++)
  	{
  		int bit0, bit1, bit2, bit3;
  		int r, g, b;
  
  		/* red component */
  		bit0 = (color_prom[i + 0x000] >> 0) & 0x01;
  		bit1 = (color_prom[i + 0x000] >> 1) & 0x01;
  		bit2 = (color_prom[i + 0x000] >> 2) & 0x01;
  		bit3 = (color_prom[i + 0x000] >> 3) & 0x01;
  		r = combine_4_weights(rweights, bit0, bit1, bit2, bit3);
  
  		/* green component */
  		bit0 = (color_prom[i + 0x100] >> 0) & 0x01;
  		bit1 = (color_prom[i + 0x100] >> 1) & 0x01;
  		bit2 = (color_prom[i + 0x100] >> 2) & 0x01;
  		bit3 = (color_prom[i + 0x100] >> 3) & 0x01;
  		g = combine_4_weights(gweights, bit0, bit1, bit2, bit3);
  
  		/* blue component */
  		bit0 = (color_prom[i + 0x200] >> 0) & 0x01;
  		bit1 = (color_prom[i + 0x200] >> 1) & 0x01;
  		bit2 = (color_prom[i + 0x200] >> 2) & 0x01;
  		bit3 = (color_prom[i + 0x200] >> 3) & 0x01;
  		b = combine_4_weights(bweights, bit0, bit1, bit2, bit3);
  
  		colortable_palette_set_color(machine->colortable, i, MAKE_RGB(r, g, b));
  	}
  
  	/* color_prom now points to the beginning of the lookup table,*/
  	color_prom += 0x300;
  
  	/* characters use colors 0xf0-0xff */
  	for (i = 0; i < 0x100; i++)
  	{
  		UINT8 ctabentry = (color_prom[i] & 0x0f) | 0xf0;
  		colortable_entry_set_value(machine->colortable, i, ctabentry);
  	}
  
  	/* sprites use colors 0-256 (?) in 16 banks */
  	for (i = 0; i < 0x100; i++)
  	{
  		int j;
  
  		for (j = 0; j < 0x10; j++)
  		{
  			UINT8 ctabentry = (j << 4) | (color_prom[i + 0x100] & 0x0f);
  			colortable_entry_set_value(machine->colortable, 0x100 + ((j << 8) | i), ctabentry);
  		}
  	}
  }
  
  WRITE8_HANDLER( sbasketb_videoram_w )
  {
  	trackfld_state *state = space->machine->driver_data<trackfld_state>();
  	state->videoram[offset] = data;
  	tilemap_mark_tile_dirty(state->bg_tilemap, offset);
  }
  
  WRITE8_HANDLER( sbasketb_colorram_w )
  {
  	trackfld_state *state = space->machine->driver_data<trackfld_state>();
  	state->colorram[offset] = data;
  	tilemap_mark_tile_dirty(state->bg_tilemap, offset);
  }
  
  WRITE8_HANDLER( sbasketb_flipscreen_w )
  {
  	if (flip_screen_get(space->machine) != data)
  	{
  		flip_screen_set(space->machine, data);
  		tilemap_mark_all_tiles_dirty_all(space->machine);
  	}
  }
  
  static TILE_GET_INFO( get_bg_tile_info )
  {
  	trackfld_state *state = machine->driver_data<trackfld_state>();
  	int code = state->videoram[tile_index] + ((state->colorram[tile_index] & 0x20) << 3);
  	int color = state->colorram[tile_index] & 0x0f;
  	int flags = ((state->colorram[tile_index] & 0x40) ? TILE_FLIPX : 0) | ((state->colorram[tile_index] & 0x80) ? TILE_FLIPY : 0);
  
  	SET_TILE_INFO(0, code, color, flags);
  }
  
  VIDEO_START( sbasketb )
  {
  	trackfld_state *state = machine->driver_data<trackfld_state>();
  
  	state->bg_tilemap = tilemap_create(machine, get_bg_tile_info, tilemap_scan_rows, 8, 8, 32, 32);
  	tilemap_set_scroll_cols(state->bg_tilemap, 32);
  }
  
  static void draw_sprites( running_machine *machine, bitmap_t *bitmap, const rectangle *cliprect )
  {
  	trackfld_state *state = machine->driver_data<trackfld_state>();
  	UINT8 *spriteram = state->spriteram;
  	int offs = (*state->spriteram_select & 0x01) * 0x100;
  	int i;
  
  	for (i = 0; i < 64; i++, offs += 4)
  	{
  		int sx = spriteram[offs + 2];
  		int sy = spriteram[offs + 3];
  
  		if (sx || sy)
  		{
  			int code  =  spriteram[offs + 0] | ((spriteram[offs + 1] & 0x20) << 3);
  			int color = (spriteram[offs + 1] & 0x0f) + 16 * *state->palettebank;
  			int flipx =  spriteram[offs + 1] & 0x40;
  			int flipy =  spriteram[offs + 1] & 0x80;
  
  			if (flip_screen_get(machine))
  			{
  				sx = 240 - sx;
  				sy = 240 - sy;
  				flipx = !flipx;
  				flipy = !flipy;
  			}
  
  			drawgfx_transpen(bitmap,cliprect,
  				machine->gfx[1],
  				code, color,
  				flipx, flipy,
  				sx, sy, 0);
  		}
  	}
  }
  
  VIDEO_UPDATE( sbasketb )
  {
  	trackfld_state *state = screen->machine->driver_data<trackfld_state>();
  	int col;
  
  	for (col = 6; col < 32; col++)
  		tilemap_set_scrolly(state->bg_tilemap, col, *state->scroll);
  
  	tilemap_draw(bitmap, cliprect, state->bg_tilemap, 0, 0);
  	draw_sprites(screen->machine, bitmap, cliprect);
  	return 0;
  }
  