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

  vidhrdw.c

  Functions to emulate the video hardware of the machine.

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

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


static int flipscreen;
static int gfx_bank,palette_bank;
static const unsigned char *color_codes;



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

  Convert the color PROMs into a more useable format.

  Donkey Kong has two 256x4 palette PROMs and one 256x4 PROM which contains
  the color codes to use for characters on a per row/column basis (groups of
  of 4 characters in the same column - actually row, since the display is
  rotated)
  The palette PROMs are connected to the RGB output this way:

  bit 3 -- 220 ohm resistor -- inverter  -- RED
        -- 470 ohm resistor -- inverter  -- RED
        -- 1  kohm resistor -- inverter  -- RED
  bit 0 -- 220 ohm resistor -- inverter  -- GREEN
  bit 3 -- 470 ohm resistor -- inverter  -- GREEN
        -- 1  kohm resistor -- inverter  -- GREEN
        -- 220 ohm resistor -- inverter  -- BLUE
  bit 0 -- 470 ohm resistor -- inverter  -- BLUE

***************************************************************************/
void dkong_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
	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;


		/* red component */
		bit0 = (color_prom[Machine->drv->total_colors] >> 1) & 1;
		bit1 = (color_prom[Machine->drv->total_colors] >> 2) & 1;
		bit2 = (color_prom[Machine->drv->total_colors] >> 3) & 1;
		*(palette++) = 255 - (0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2);
		/* green component */
		bit0 = (color_prom[0] >> 2) & 1;
		bit1 = (color_prom[0] >> 3) & 1;
		bit2 = (color_prom[Machine->drv->total_colors] >> 0) & 1;
		*(palette++) = 255 - (0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2);
		/* blue component */
		bit0 = (color_prom[0] >> 0) & 1;
		bit1 = (color_prom[0] >> 1) & 1;
		*(palette++) = 255 - (0x55 * bit0 + 0xaa * bit1);

		color_prom++;
	}

	color_prom += Machine->drv->total_colors;
	/* color_prom now points to the beginning of the character color codes */
	color_codes = color_prom;	/* we'll need it later */

	/* sprites use the same palette as characters */
	for (i = 0;i < TOTAL_COLORS(0);i++)
		COLOR(0,i) = i;
}

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

  Convert the color PROMs into a more useable format.

  Donkey Kong 3 has two 512x8 palette PROMs and one 256x4 PROM which contains
  the color codes to use for characters on a per row/column basis (groups of
  of 4 characters in the same column - actually row, since the display is
  rotated)
  Interstingly, bytes 0-255 of the palette PROMs contain an inverted palette,
  as other Nintendo games like Donkey Kong, while bytes 256-511 contain a non
  inverted palette. This was probably done to allow connection to both the
  special Nintendo and a standard monitor.
  I don't know the exact values of the resistors between the PROMs and the
  RGB output, but they are probably the usual:

  bit 7 -- 220 ohm resistor -- inverter  -- RED
        -- 470 ohm resistor -- inverter  -- RED
        -- 1  kohm resistor -- inverter  -- RED
        -- 2.2kohm resistor -- inverter  -- RED
        -- 220 ohm resistor -- inverter  -- GREEN
        -- 470 ohm resistor -- inverter  -- GREEN
        -- 1  kohm resistor -- inverter  -- GREEN
  bit 0 -- 2.2kohm resistor -- inverter  -- GREEN

  bit 3 -- 220 ohm resistor -- inverter  -- BLUE
        -- 470 ohm resistor -- inverter  -- BLUE
        -- 1  kohm resistor -- inverter  -- BLUE
  bit 0 -- 2.2kohm resistor -- inverter  -- BLUE

***************************************************************************/
void dkong3_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
	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;


		/* red component */
		bit0 = (color_prom[0] >> 4) & 0x01;
		bit1 = (color_prom[0] >> 5) & 0x01;
		bit2 = (color_prom[0] >> 6) & 0x01;
		bit3 = (color_prom[0] >> 7) & 0x01;
		*(palette++) = 255 - (0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3);
		/* green component */
		bit0 = (color_prom[0] >> 0) & 0x01;
		bit1 = (color_prom[0] >> 1) & 0x01;
		bit2 = (color_prom[0] >> 2) & 0x01;
		bit3 = (color_prom[0] >> 3) & 0x01;
		*(palette++) = 255 - (0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3);
		/* blue component */
		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;
		*(palette++) = 255 - (0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3);

		color_prom++;
	}

	color_prom += Machine->drv->total_colors;
	/* color_prom now points to the beginning of the character color codes */
	color_codes = color_prom;	/* we'll need it later */

	/* sprites use the same palette as characters */
	for (i = 0;i < TOTAL_COLORS(0);i++)
		COLOR(0,i) = i;
}



int dkong_vh_start(void)
{
	gfx_bank = 0;
	palette_bank = 0;

	return generic_vh_start();
}



void dkongjr_gfxbank_w(int offset,int data)
{
	if (gfx_bank != (data & 1))
	{
		gfx_bank = data & 1;
		memset(dirtybuffer,1,videoram_size);
	}
}

void dkong3_gfxbank_w(int offset,int data)
{
	if (gfx_bank != (~data & 1))
	{
		gfx_bank = ~data & 1;
		memset(dirtybuffer,1,videoram_size);
	}
}



void dkong_palettebank_w(int offset,int data)
{
	int newbank;


	newbank = palette_bank;
	if (data & 1)
		newbank |= 1 << offset;
	else
		newbank &= ~(1 << offset);

	if (palette_bank != newbank)
	{
		palette_bank = newbank;
		memset(dirtybuffer,1,videoram_size);
	}
}

void dkong_flipscreen_w(int offset,int data)
{
	if (flipscreen != (~data & 1))
	{
		flipscreen = ~data & 1;
		memset(dirtybuffer,1,videoram_size);
	}
}

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

  Draw the game screen in the given osd_bitmap.
  Do NOT call osd_update_display() from this function, it will be called by
  the main emulation engine.

***************************************************************************/
void dkong_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
	int offs;

	/* for every character in the Video RAM, check if it has been modified */
	/* since last time and update it accordingly. */
	for (offs = videoram_size - 1;offs >= 0;offs--)
	{
		if (dirtybuffer[offs])
		{
			int sx,sy;
			int charcode,color;


			dirtybuffer[offs] = 0;

			sx = offs % 32;
			sy = offs / 32;

			charcode = videoram[offs] + 256 * gfx_bank;
			/* retrieve the character color from the PROM */
			color = (color_codes[offs % 32 + 32 * (offs / 32 / 4)] & 0x0f) + 0x10 * palette_bank;

			if (flipscreen)
			{
				sx = 31 - sx;
				sy = 31 - sy;
			}

			drawgfx(tmpbitmap,Machine->gfx[0],
					charcode,color,
					flipscreen,flipscreen,
					8*sx,8*sy,
					&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
		}
	}


	/* copy the character mapped graphics */
	copybitmap(bitmap,tmpbitmap,0,0,0,0,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);


	/* Draw the sprites. */
	for (offs = 0;offs < spriteram_size;offs += 4)
	{
		if (spriteram[offs])
		{
			/* spriteram[offs + 2] & 0x40 is used by Donkey Kong 3 only */
			/* spriteram[offs + 2] & 0x30 don't seem to be used (they are */
			/* probably not part of the color code, since Mario Bros, which */
			/* has similar hardware, uses a memory mapped port to change */
			/* palette bank, so it's limited to 16 color codes) */

			int x,y;

			x = spriteram[offs + 3] - 8;
			y = 240 - spriteram[offs] + 7;

			if (flipscreen)
			{
				x = 240 - x;
				y = 240 - y;

				drawgfx(bitmap,Machine->gfx[1],
						(spriteram[offs + 1] & 0x7f) + 2 * (spriteram[offs + 2] & 0x40),
						(spriteram[offs + 2] & 0x0f) + 16 * palette_bank,
						!(spriteram[offs + 2] & 0x80),!(spriteram[offs + 1] & 0x80),
						x,y,
						&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
			}
			else
			{
				drawgfx(bitmap,Machine->gfx[1],
						(spriteram[offs + 1] & 0x7f) + 2 * (spriteram[offs + 2] & 0x40),
						(spriteram[offs + 2] & 0x0f) + 16 * palette_bank,
						(spriteram[offs + 2] & 0x80),(spriteram[offs + 1] & 0x80),
						x,y,
						&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
			}
		}
	}
}
