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

  video.c

  Functions to emulate the video hardware of the machine.

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

#include "driver.h"

static int palettebank;

static tilemap *bg_tilemap;

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

  Convert the color PROMs into a more useable format.

  Mikie 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( mikie )
{
	int i;
	#define TOTAL_COLORS(gfxn) (machine->gfx[gfxn]->total_colors * machine->gfx[gfxn]->color_granularity)
	#define COLOR(gfxn,offs) (colortable[machine->drv->gfxdecodeinfo[gfxn].color_codes_start + offs])


	for (i = 0;i < machine->drv->total_colors;i++)
	{
		int bit0,bit1,bit2,bit3,r,g,b;


		bit0 = (color_prom[0] >> 0) & 0x01;
		bit1 = (color_prom[0] >> 1) & 0x01;
		bit2 = (color_prom[0] >> 2) & 0x01;
		bit3 = (color_prom[0] >> 3) & 0x01;
		r = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;
		bit0 = (color_prom[machine->drv->total_colors] >> 0) & 0x01;
		bit1 = (color_prom[machine->drv->total_colors] >> 1) & 0x01;
		bit2 = (color_prom[machine->drv->total_colors] >> 2) & 0x01;
		bit3 = (color_prom[machine->drv->total_colors] >> 3) & 0x01;
		g = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;
		bit0 = (color_prom[2*machine->drv->total_colors] >> 0) & 0x01;
		bit1 = (color_prom[2*machine->drv->total_colors] >> 1) & 0x01;
		bit2 = (color_prom[2*machine->drv->total_colors] >> 2) & 0x01;
		bit3 = (color_prom[2*machine->drv->total_colors] >> 3) & 0x01;
		b = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;

		palette_set_color(machine,i,r,g,b);

		color_prom++;
	}

	color_prom += 2*machine->drv->total_colors;
	/* color_prom now points to the beginning of the character lookup table */


	/* there are eight 32 colors palette banks; sprites use colors 0-15 and */
	/* characters 16-31 of each bank. */
	for (i = 0;i < TOTAL_COLORS(0)/8;i++)
	{
		int j;


		for (j = 0;j < 8;j++)
			COLOR(0,i + j * TOTAL_COLORS(0)/8) = (*color_prom & 0x0f) + 32 * j + 16;

		color_prom++;
	}

	for (i = 0;i < TOTAL_COLORS(1)/8;i++)
	{
		int j;


		for (j = 0;j < 8;j++)
			COLOR(1,i + j * TOTAL_COLORS(1)/8) = (*color_prom & 0x0f) + 32 * j;

		color_prom++;
	}
}

WRITE8_HANDLER( mikie_videoram_w )
{
	if (videoram[offset] != data)
	{
		videoram[offset] = data;
		tilemap_mark_tile_dirty(bg_tilemap, offset);
	}
}

WRITE8_HANDLER( mikie_colorram_w )
{
	if (colorram[offset] != data)
	{
		colorram[offset] = data;
		tilemap_mark_tile_dirty(bg_tilemap, offset);
	}
}

WRITE8_HANDLER( mikie_palettebank_w )
{
	if (palettebank != (data & 0x07))
	{
		palettebank = data & 0x07;
		tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
	}
}

WRITE8_HANDLER( mikie_flipscreen_w )
{
	if (flip_screen != (data & 0x01))
	{
		flip_screen_set(data & 0x01);
		tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
	}
}

static void get_bg_tile_info(int tile_index)
{
	int code = videoram[tile_index] + ((colorram[tile_index] & 0x20) << 3);
	int color = (colorram[tile_index] & 0x0f) + 16 * palettebank;
	int flags = ((colorram[tile_index] & 0x40) ? TILE_FLIPX : 0) | ((colorram[tile_index] & 0x80) ? TILE_FLIPY : 0);

	SET_TILE_INFO(0, code, color, flags)
}

VIDEO_START( mikie )
{
	bg_tilemap = tilemap_create(get_bg_tile_info, tilemap_scan_rows,
		TILEMAP_OPAQUE, 8, 8, 32, 32);

	return 0;
}

static void mikie_draw_sprites( mame_bitmap *bitmap )
{
	int offs;

	for (offs = 0;offs < spriteram_size;offs += 4)
	{
		int gfxbank = (spriteram[offs+2] & 0x40) ? 2 : 1;
		int code = (spriteram[offs + 2] & 0x3f) + ((spriteram[offs + 2] & 0x80) >> 1) + ((spriteram[offs] & 0x40) << 1);
		int color = (spriteram[offs] & 0x0f) + 16 * palettebank;
		int sx = spriteram[offs + 3];
		int sy = 244 - spriteram[offs + 1];
		int flipx = ~spriteram[offs] & 0x10;
		int flipy = spriteram[offs] & 0x20;

		if (flip_screen)
		{
			sy = 242 - sy;
			flipy = !flipy;
		}

		drawgfx(bitmap, Machine->gfx[gfxbank],
			code, color,
			flipx,flipy,
			sx,sy,
			&Machine->screen[0].visarea,
			TRANSPARENCY_PEN, 0);
	}
}

VIDEO_UPDATE( mikie )
{
	tilemap_draw(bitmap, &machine->screen[0].visarea, bg_tilemap, 0, 0);
	mikie_draw_sprites(bitmap);
	return 0;
}
