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

    Atari Centipede hardware

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

#include "driver.h"
#include "vidhrdw/generic.h"
#include "centiped.h"


static struct tilemap *tilemap;
UINT8 centiped_flipscreen, *bullsdrt_tiles_bankram;
static UINT8 bullsdrt_sprites_bank;
static UINT8 penmask[64];



/*************************************
 *
 *  Tilemap callback
 *
 *************************************/

static void centiped_get_tile_info(int tile_index)
{
	int data = videoram[tile_index];
	SET_TILE_INFO(0, (data & 0x3f) + 0x40, 0, TILE_FLIPYX(data >> 6));
}


static void warlords_get_tile_info(int tile_index)
{
	int data = videoram[tile_index];
	int color = ((tile_index & 0x10) >> 4) | ((tile_index & 0x200) >> 8) | (centiped_flipscreen >> 5);
	SET_TILE_INFO(0, data & 0x3f, color, TILE_FLIPYX(data >> 6));
}


static void milliped_get_tile_info(int tile_index)
{
	int data = videoram[tile_index];
	int bank = (data >> 6) & 1;
	int color = (data >> 6) & 3;
	SET_TILE_INFO(0, (data & 0x3f) + 0x40 + (bank * 0x80), color, 0);
}


static void bullsdrt_get_tile_info(int tile_index)
{
	int data = videoram[tile_index];
	int bank = bullsdrt_tiles_bankram[tile_index & 0x1f] & 0x0f;
	SET_TILE_INFO(0, (data & 0x3f) + 0x40 * bank, 0, TILE_FLIPYX(data >> 6));
}



/*************************************
 *
 *  Video system start
 *
 *************************************/

VIDEO_START( centiped )
{
	tilemap = tilemap_create(centiped_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8,8, 32,32);
	if (!tilemap)
		return 1;

	centiped_flipscreen = 0;
	return 0;
}


VIDEO_START( warlords )
{
	tilemap = tilemap_create(warlords_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8,8, 32,32);
	if (!tilemap)
		return 1;

	/* we overload centiped_flipscreen here to track the cocktail/upright state */
	centiped_flipscreen = readinputport(0) & 0x80;
	tilemap_set_flip(tilemap, centiped_flipscreen ? TILEMAP_FLIPX : 0);
	return 0;
}


VIDEO_START( milliped )
{
	tilemap = tilemap_create(milliped_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8,8, 32,32);
	if (!tilemap)
		return 1;

	centiped_flipscreen = 0;
	return 0;
}


VIDEO_START( bullsdrt )
{
	tilemap = tilemap_create(bullsdrt_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8,8, 32,32);
	if (!tilemap)
		return 1;

	centiped_flipscreen = 0;
	return 0;
}



/*************************************
 *
 *  Video RAM writes
 *
 *************************************/

WRITE8_HANDLER( centiped_videoram_w )
{
	videoram[offset] = data;
	tilemap_mark_tile_dirty(tilemap, offset);
}



/*************************************
 *
 *  Screen flip
 *
 *************************************/

WRITE8_HANDLER( centiped_flip_screen_w )
{
	centiped_flipscreen = data >> 7;
}



/*************************************
 *
 *  Tiles bank
 *
 *************************************/

WRITE8_HANDLER( bullsdrt_tilesbank_w )
{
	bullsdrt_tiles_bankram[offset] = data;
	tilemap_mark_all_tiles_dirty(tilemap);
}



/*************************************
 *
 *  Sprites bank
 *
 *************************************/

WRITE8_HANDLER( bullsdrt_sprites_bank_w )
{
	bullsdrt_sprites_bank = data;
}



/*************************************
 *
 *  Palette init
 *
 *************************************/

static void init_penmask(void)
{
	int i;

	for (i = 0; i < 64; i++)
	{
		UINT8 mask = 1;
		if (((i >> 0) & 3) == 0) mask |= 2;
		if (((i >> 2) & 3) == 0) mask |= 4;
		if (((i >> 4) & 3) == 0) mask |= 8;
		penmask[i] = mask;
	}
}



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

    Centipede doesn't have a color PROM. Eight RAM locations control
    the color of characters and sprites. The meanings of the four bits are
    (all bits are inverted):

    bit 3 alternate
          blue
          green
    bit 0 red

    The alternate bit affects blue and green, not red. The way I weighted its
    effect might not be perfectly accurate, but is reasonably close.

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

#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])

PALETTE_INIT( centiped )
{
	int i;

	/* characters use colors 0-3 */
	for (i = 0; i < TOTAL_COLORS(0); i++)
		COLOR(0,i) = i;

	/* Centipede is unusual because the sprite color code specifies the */
	/* colors to use one by one, instead of a combination code. */
	/* bit 5-4 = color to use for pen 11 */
	/* bit 3-2 = color to use for pen 10 */
	/* bit 1-0 = color to use for pen 01 */
	/* pen 00 is transparent */
	for (i = 0; i < TOTAL_COLORS(1); i += 4)
	{
		COLOR(1,i+0) = 0;
		COLOR(1,i+1) = 4 + ((i >> 2) & 3);
		COLOR(1,i+2) = 4 + ((i >> 4) & 3);
		COLOR(1,i+3) = 4 + ((i >> 6) & 3);
	}

	/* create a pen mask for sprite drawing */
	init_penmask();
}


WRITE8_HANDLER( centiped_paletteram_w )
{
	int r, g, b;

	paletteram[offset] = data;

	r = 0xff * ((~data >> 0) & 1);
	g = 0xff * ((~data >> 1) & 1);
	b = 0xff * ((~data >> 2) & 1);

	if (~data & 0x08) /* alternate = 1 */
	{
		/* when blue component is not 0, decrease it. When blue component is 0, */
		/* decrease green component. */
		if (b) b = 0xc0;
		else if (g) g = 0xc0;
	}

	/* bit 2 of the output palette RAM is always pulled high, so we ignore */
	/* any palette changes unless the write is to a palette RAM address */
	/* that is actually used */
	if (offset & 4)
		palette_set_color(((offset >> 1) & 4) | (offset & 3), r, g, b);
}



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

    Convert the color PROM into a more useable format.

    The palette PROM are connected to the RGB output this way:

    bit 2 -- RED
          -- GREEN
    bit 0 -- BLUE

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

PALETTE_INIT( warlords )
{
	int i, j;

	for (i = 0; i < Machine->drv->total_colors; i++)
	{
		int r = ((*color_prom >> 2) & 0x01) * 0xff;
		int g = ((*color_prom >> 1) & 0x01) * 0xff;
		int b = ((*color_prom >> 0) & 0x01) * 0xff;

		/* Colors 0x40-0x7f are converted to grey scale as it's used on the
           upright version that had an overlay */
		if (i >= Machine->drv->total_colors / 2)
		{
			/* Use the standard ratios: r = 30%, g = 59%, b = 11% */
			int grey = (r * 0x4d / 0xff) + (g * 0x96 / 0xff) + (b * 0x1c / 0xff);
			r = g = b = grey;
		}
		palette_set_color(i,r,g,b);
		color_prom++;
	}

	for (i = 0; i < 8; i++)
		for (j = 0; j < 4; j++)
		{
			COLOR(0,i*4+j) = i*16+j;
			COLOR(1,i*4+j) = i*16+j*4;
		}
}



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

    Millipede doesn't have a color PROM, it uses RAM.
    The RAM seems to be conncted to the video output this way:

    bit 7 red
          red
          red
          green
          green
          blue
          blue
    bit 0 blue

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

PALETTE_INIT( milliped )
{
	int i;

	/* characters use colors 0-15 */
	for (i = 0; i < TOTAL_COLORS(0); i++)
		COLOR(0,i) = i;

	/* Millipede is unusual because the sprite color code specifies the */
	/* colors to use one by one, instead of a combination code. */
	/* bit 7-6 = palette bank (there are 4 groups of 4 colors) */
	/* bit 5-4 = color to use for pen 11 */
	/* bit 3-2 = color to use for pen 10 */
	/* bit 1-0 = color to use for pen 01 */
	/* pen 00 is transparent */
	for (i = 0; i < TOTAL_COLORS(1); i += 4)
	{
		int base = 16 + 4 * ((i >> 8) & 3);
		COLOR(1,i+0) = 0;
		COLOR(1,i+1) = base + ((i >> 2) & 3);
		COLOR(1,i+2) = base + ((i >> 4) & 3);
		COLOR(1,i+3) = base + ((i >> 6) & 3);
	}

	/* create a pen mask for sprite drawing */
	init_penmask();
}


WRITE8_HANDLER( milliped_paletteram_w )
{
	int bit0,bit1,bit2;
	int r,g,b;

	paletteram[offset] = data;

	/* red component */
	bit0 = (~data >> 5) & 0x01;
	bit1 = (~data >> 6) & 0x01;
	bit2 = (~data >> 7) & 0x01;
	r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

	/* green component */
	bit0 = 0;
	bit1 = (~data >> 3) & 0x01;
	bit2 = (~data >> 4) & 0x01;
	g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

	/* blue component */
	bit0 = (~data >> 0) & 0x01;
	bit1 = (~data >> 1) & 0x01;
	bit2 = (~data >> 2) & 0x01;
	b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

	palette_set_color(offset, r, g, b);
}



/*************************************
 *
 *  Video update
 *
 *************************************/

VIDEO_UPDATE( centiped )
{
	struct rectangle spriteclip = *cliprect;
	int offs;

	/* draw the background */
	tilemap_draw(bitmap, cliprect, tilemap, 0, 0);

	/* apply the sprite clip */
	if (centiped_flipscreen)
		spriteclip.min_x += 8;
	else
		spriteclip.max_x -= 8;

	/* draw the sprites */
	for (offs = 0; offs < 0x10; offs++)
	{
		int code = ((spriteram[offs] & 0x3e) >> 1) | ((spriteram[offs] & 0x01) << 6);
		int color = spriteram[offs + 0x30];
		int flipx = (spriteram[offs] >> 6) & 1;
		int flipy = (spriteram[offs] >> 7) & 1;
		int x = spriteram[offs + 0x20];
		int y = 240 - spriteram[offs + 0x10];

		drawgfx(bitmap, Machine->gfx[1], code, color, centiped_flipscreen ^ flipx, flipy, x, y,
				&spriteclip, TRANSPARENCY_PENS, penmask[color & 0x3f]);
	}
}


VIDEO_UPDATE( warlords )
{
	int upright_mode = input_port_0_r(0) & 0x80;
	int offs;

	/* if the cocktail/upright switch flipped, force refresh */
	if (centiped_flipscreen != upright_mode)
	{
		centiped_flipscreen = upright_mode;
		tilemap_set_flip(tilemap, upright_mode ? TILEMAP_FLIPX : 0);
		tilemap_mark_all_tiles_dirty(tilemap);
	}

	/* draw the background */
	tilemap_draw(bitmap, cliprect, tilemap, 0, 0);

	/* draw the sprites */
	for (offs = 0; offs < 0x10; offs++)
	{
		int code = spriteram[offs] & 0x3f;
		int flipx = (spriteram[offs] >> 6) & 1;
		int flipy = (spriteram[offs] >> 7) & 1;
		int x = spriteram[offs + 0x20];
		int y = 248 - spriteram[offs + 0x10];

		/* The four quadrants have different colors. This is not 100% accurate,
           because right on the middle the sprite could actually have two or more
           different color, but this is not noticable, as the color that
           changes between the quadrants is mostly used on the paddle sprites */
		int color = ((y & 0x80) >> 6) | ((x & 0x80) >> 7) | (upright_mode >> 5);

		/* in upright mode, sprites are flipped */
		if (upright_mode)
		{
			x = 248 - x;
			flipx = !flipx;
		}

		drawgfx(bitmap, Machine->gfx[1], code, color, flipx, flipy, x, y,
				cliprect, TRANSPARENCY_PEN, 0);
	}
}


VIDEO_UPDATE( bullsdrt )
{
	struct rectangle spriteclip = *cliprect;

	int offs;

	/* draw the background */
	tilemap_draw(bitmap, cliprect, tilemap, 0, 0);

	/* apply the sprite clip */
	if (centiped_flipscreen)
		spriteclip.min_x += 8;
	else
		spriteclip.max_x -= 8;

	/* draw the sprites */
	for (offs = 0; offs < 0x10; offs++)
	{
		int code = ((spriteram[offs] & 0x3e) >> 1) | ((spriteram[offs] & 0x01) << 6) | (bullsdrt_sprites_bank * 0x20);
		int color = spriteram[offs + 0x30];
		int flipy = (spriteram[offs] >> 7) & 1;
		int x = spriteram[offs + 0x20];
		int y = 240 - spriteram[offs + 0x10];

		drawgfx(bitmap, Machine->gfx[1], code, color & 0x3f, 1, flipy, x, y,
				&spriteclip, TRANSPARENCY_PEN, 0);
	}
}
