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

	Atari Tunnel Hunt hardware

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

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

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

/* Video Hardware Addresses */

/* Square Generator (13 bytes each) */
#define LINEV	0x1403	// LINES VERTICAL START
#define LINEVS	0x1483	// LINES VERT STOP
#define LINEH	0x1083	// LINES HORIZ START
#define LINEC	0x1283	// LINE COLOR, 4 BITS D0-D3
#define LINESH	0x1203	// LINES SLOPE 4 BITS D0-D3 (signed)
/* LINESH was used for rotation effects in an older version of the game */

/* Shell Object0 */
#define SHEL0H	0x1800	// SHELL H POSITON (NORMAL SCREEN)
#define SHL0V	0x1400	// SHELL V START(NORMAL SCREEN)
#define SHL0VS	0x1480	// SHELL V STOP (NORMAL SCREEN)
#define SHL0ST	0x1200	// SHELL VSTRETCH (LIKE MST OBJ STRECTH)
#define SHL0PC	0x1280	// SHELL PICTURE CODE (D3-D0)

/* Shell Object1 (see above) */
#define SHEL1H	0x1A00
#define SHL1V	0x1401
#define SHL1VS	0x1481
#define SHL1ST	0x1201
#define SHL1PC	0x1281

/* Motion Object RAM */
#define MOBJV	0x1C00	// V POSITION (SCREEN ON SIDE)
#define MOBVS	0x1482	// V STOP OF MOTION OBJECT (NORMAL SCREEN)
#define MOBJH	0x1402	// H POSITON (SCREEN ON SIDE) (VSTART - NORMAL SCREEN)
#define MOBST	0x1082	// STARTING LINE FOR RAM SCAN ON MOBJ
#define VSTRLO	0x1202	// VERT (SCREEN ON SIDE) STRETCH MOJ OBJ
#define MOTT	0x2C00	// MOTION OBJECT RAM (00-0F NOT USED, BYT CLEARED)
#define MOBSC0	0x1080	// SCAN ROM START FOR MOBJ (unused?)
#define MOBSC1	0x1081	// (unused?)

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

WRITE_HANDLER( tunhunt_mott_w )
{
	if( spriteram[offset]!=data )
	{
		spriteram[offset] = data;
		dirtybuffer[offset>>4] = 1;
	}
}

VIDEO_START( tunhunt )
{
	/*
	Motion Object RAM contains 64 lines of run-length encoded data.
	We keep track of dirty lines and cache the expanded bitmap.
	With max RLE expansion, bitmap size is 256x64.
	*/
	dirtybuffer = auto_malloc(64);
	if (!dirtybuffer)
		return 1;

	memset( dirtybuffer, 1, 64 );
	tmpbitmap = auto_bitmap_alloc( 256, 64 );
	if (!tmpbitmap)
		return 1;

	return 0;
}

PALETTE_INIT( tunhunt )
{
	/* Tunnel Hunt uses a combination of color proms and palette RAM to specify a 16 color
	 * palette.  Here, we manage only the mappings for alphanumeric characters and SHELL
	 * graphics, which are unpacked ahead of time and drawn using MAME's drawgfx primitives.
	 */

	/* AlphaNumerics (1bpp)
	 *	2 bits of hilite select from 4 different background colors
	 *	Foreground color is always pen#4
	 *	Background color is mapped as follows:
	 */

	/* alpha hilite#0 */
	colortable[0] = 0x0; /* background color#0 (transparent) */
	colortable[1] = 0x4; /* foreground color */

	/* alpha hilite#1 */
	colortable[2] = 0x5; /* background color#1 */
	colortable[3] = 0x4; /* foreground color */

	/* alpha hilite#2 */
	colortable[4] = 0x6; /* background color#2 */
	colortable[5] = 0x4; /* foreground color */

	/* alpha hilite#3 */
	colortable[6] = 0xf; /* background color#3 */
	colortable[7] = 0x4; /* foreground color */

	/* shell graphics; these are either 1bpp (2 banks) or 2bpp.  It isn't clear which.
	 * In any event, the following pens are associated with the shell graphics:
	 */
	colortable[0x8] = 0;
	colortable[0x9] = 4;//1;
	colortable[0xa] = 2;
	colortable[0xb] = 4;
}

/*
Color Array Ram Assignments:
    Location
        0               Blanking, border
        1               Mot Obj (10) (D), Shell (01)
        2               Mot Obj (01) (G), Shell (10)
        3               Mot Obj (00) (W)
        4               Alpha & Shell (11) - shields
        5               Hilight 1
        6               Hilight 2
        8-E             Lines (as normal) background
        F               Hilight 3
*/
static void update_palette( void )
{
//	const unsigned char *color_prom = memory_region( REGION_PROMS );
/*
	The actual contents of the color proms (unused by this driver)
	are as follows:

	D11 "blue/green"
	0000:	00 00 8b 0b fb 0f ff 0b
			00 00 0f 0f fb f0 f0 ff

	C11 "red"
	0020:	00 f0 f0 f0 b0 b0 00 f0
			00 f0 f0 00 b0 00 f0 f0
*/
	int color;
	int shade;
	int i;
	int red,green,blue;

	for( i=0; i<16; i++ )
	{
		color = paletteram[i];
		shade = 0xf^(color>>4);

		color &= 0xf; /* hue select */
		switch( color )
		{
		default:
		case 0x0: red = 0xff; green = 0xff; blue = 0xff; break; /* white */
		case 0x1: red = 0xff; green = 0x00; blue = 0xff; break; /* purple */
		case 0x2: red = 0x00; green = 0x00; blue = 0xff; break; /* blue */
		case 0x3: red = 0x00; green = 0xff; blue = 0xff; break; /* cyan */
		case 0x4: red = 0x00; green = 0xff; blue = 0x00; break; /* green */
		case 0x5: red = 0xff; green = 0xff; blue = 0x00; break; /* yellow */
		case 0x6: red = 0xff; green = 0x00; blue = 0x00; break; /* red */
		case 0x7: red = 0x00; green = 0x00; blue = 0x00; break; /* black? */

		case 0x8: red = 0xff; green = 0x7f; blue = 0x00; break; /* orange */
		case 0x9: red = 0x7f; green = 0xff; blue = 0x00; break; /* ? */
		case 0xa: red = 0x00; green = 0xff; blue = 0x7f; break; /* ? */
		case 0xb: red = 0x00; green = 0x7f; blue = 0xff; break; /* ? */
		case 0xc: red = 0xff; green = 0x00; blue = 0x7f; break; /* ? */
		case 0xd: red = 0x7f; green = 0x00; blue = 0xff; break; /* ? */
		case 0xe: red = 0xff; green = 0xaa; blue = 0xaa; break; /* ? */
		case 0xf: red = 0xaa; green = 0xaa; blue = 0xff; break; /* ? */
		}

	/* combine color components with shade value (0..0xf) */
		#define APPLY_SHADE( C,S ) ((C*S)/0xf)
		red		= APPLY_SHADE(red,shade);
		green	= APPLY_SHADE(green,shade);
		blue	= APPLY_SHADE(blue,shade);

		palette_set_color( i,red,green,blue );
	}
}

static void draw_text( struct mame_bitmap *bitmap )
{
	/* 8 columns, 32 rows */
	int offs;
	int sx,sy,tile,color;
	const UINT8 *source = videoram;
	for( offs=0; offs<0x100; offs++ )
	{
		sx = (offs/32)*8 + 256 - 64;
		sy = (offs%32)*8;
		tile = source[offs];
		color = tile>>6;

		drawgfx( bitmap, Machine->gfx[0],
			tile&0x3f,	/* lower 6 bits of character code */
			color,		/* upper 2 bits of character code */
			0,0,		/* flipx, flipy */
			sx,sy,		/* character placement */
			&Machine->visible_area, /* clip */
			/* if hilite = 0, make the character background transparent */
			(color==0)?TRANSPARENCY_PEN:TRANSPARENCY_NONE,
			0 );
	}
}

static void draw_motion_object( struct mame_bitmap *bitmap )
{
/*
 *		VSTRLO	0x1202
 *			normally 0x02 (gameplay, attract1)
 *			in attract2 (with "Tunnel Hunt" graphic), decrements from 0x2f down to 0x01
 *			goes to 0x01 for some enemy shots
 *
 *		MOBSC0	0x1080
 *		MOBSC1	0x1081
 *			always 0x00?
 */
	const UINT8 *pMem = memory_region( REGION_CPU1 );
//	int skip = pMem[MOBST];
	int x0 = 255-pMem[MOBJV];
	int y0 = 255-pMem[MOBJH];
	int scalex,scaley;
	int line,span;
	int x,span_data;
	int color;
	int count,pen;
	const unsigned char *source;
	struct rectangle clip = Machine->visible_area;

	for( line=0; line<64; line++ )
	{
		if( dirtybuffer[line] )
		{
			dirtybuffer[line] = 0;
			x = 0;
			source = &spriteram[line*0x10];
			for( span=0; span<0x10; span++ )
			{
				span_data = source[span];
				if( span_data == 0xff ) break;
				pen = ((span_data>>6)&0x3)^0x3;
				color = Machine->pens[pen];
				count = (span_data&0x1f)+1;
				while( count-- )
				{
					plot_pixel( tmpbitmap, x++,line,color );
				}
			}
			color = Machine->pens[0];
			while( x<256 )
			{
				plot_pixel( tmpbitmap, x++,line,color );
			}
		} /* dirty line */
	} /* next line */

	switch( pMem[VSTRLO] )
	{
	case 0x01:
		scaley = (1<<16)*0.33; /* seems correct */
		break;

	case 0x02:
		scaley = (1<<16)*0.50; /* seems correct */
		break;

	default:
		scaley = (1<<16)*pMem[VSTRLO]/4; /* ??? */
		break;
	}
	scalex = (1<<16);

	copyrozbitmap(
		bitmap,tmpbitmap,
		-x0*scalex,/* startx */
		-y0*scaley,/* starty */
		scalex,/* incxx */
		0,0,/* incxy,incyx */
		scaley,/* incyy */
		0, /* no wraparound */
		&clip,
		TRANSPARENCY_PEN,Machine->pens[0],
		0 /* priority */
	);
}

static void draw_box( struct mame_bitmap *bitmap )
{
/*
	This is unnecessarily slow, but the box priorities aren't completely understood,
	yet.  Once understood, this function should be converted to use fillbitmap with
	rectangular chunks instead of plot_pixel.

	Tunnels:
		1080: 00 00 00 		01	e7 18   ae 51   94 6b   88 77   83 7c   80 7f  	x0
		1480: 00 f0 17 		00	22 22   5b 5b   75 75   81 81   86 86   89 89  	y0
		1400: 00 00 97 		ff	f1 f1   b8 b8   9e 9e   92 92   8d 8d   8a 8a  	y1
		1280: 07 03 00 		07	07 0c   0c 0d   0d 0e   0e 08   08 09   09 0a  	palette select

	Color Bars:
		1080: 00 00 00 		01	00 20 40 60 80 a0 c0 e0		01 2a	50 7a		x0
		1480: 00 f0 00 		00	40 40 40 40 40 40 40 40		00 00	00 00		y0
		1400: 00 00 00 		ff	ff ff ff ff ff ff ff ff		40 40	40 40		y1
		1280: 07 03 00 		01	07 06 04 05 02 07 03 00		09 0a	0b 0c		palette select
		->hue 06 02 ff 		60	06 05 03 04 01 06 02 ff		d2 00	c2 ff
*/
	int span,x,y;
	UINT8 *pMem;
	int color;
	int pen;
//	struct rectangle bbox;
	int z;
	int x0,y0,y1;
	pMem = memory_region( REGION_CPU1 );

	for( y=0; y<256; y++ )
	{
		for( x=0; x<256; x++ )
		{
			pen = 0;
			z = 0;
			for( span=3; span<16; span++ )
			{
				x0 = pMem[span+0x1080];
				y0 = pMem[span+0x1480];
				y1 = pMem[span+0x1400];

				if( y>=y0 && y<=y1 && x>=x0 && x0>=z )
				{
					pen = pMem[span+0x1280]&0xf;
					z = x0; /* give priority to rightmost spans */
				}
			}
			color = Machine->pens[pen];
			plot_pixel( bitmap, x, 0xff-y, color );
		}
	}
	return;
}

/* "shell" graphics are 16x16 pixel tiles used for player shots and targeting cursor */
static void draw_shell(
		struct mame_bitmap *bitmap,
		int picture_code,
		int hposition,
		int vstart,
		int vstop,
		int vstretch,
		int hstretch )
{
	if( hstretch )
	{
		int sx,sy;
		for( sx=0; sx<256; sx+=16 )
		{
			for( sy=0; sy<256; sy+=16 )
			{
				drawgfx( bitmap, Machine->gfx[1],
					picture_code,
					0, /* color */
					0,0, /* flip */
					sx,sy,
					&Machine->visible_area,
					TRANSPARENCY_PEN,0 );
			}
		}
	}
	else
	/*
		vstretch is normally 0x01

		targeting cursor:
			hposition	= 0x78
			vstart		= 0x90
			vstop		= 0x80

		during grid test:
			vstretch	= 0xff
			hposition	= 0xff
			vstart		= 0xff
			vstop		= 0x00

	*/
	drawgfx( bitmap, Machine->gfx[1],
			picture_code,
			0, /* color */
			0,0, /* flip */
			255-hposition-16,vstart-32,
			&Machine->visible_area,
			TRANSPARENCY_PEN,0 );
}

VIDEO_UPDATE( tunhunt )
{
	const UINT8 *pMem = memory_region( REGION_CPU1 );

	update_palette();

	draw_box( bitmap );

	draw_motion_object( bitmap );

	draw_shell( bitmap,
		pMem[SHL0PC],	/* picture code */
		pMem[SHEL0H],	/* hposition */
		pMem[SHL0V],	/* vstart */
		pMem[SHL0VS],	/* vstop */
		pMem[SHL0ST],	/* vstretch */
		tunhunt_control&0x08 ); /* hstretch */

	draw_shell( bitmap,
		pMem[SHL1PC],	/* picture code */
		pMem[SHEL1H],	/* hposition */
		pMem[SHL1V],	/* vstart */
		pMem[SHL1VS],	/* vstop */
		pMem[SHL1ST],	/* vstretch */
		tunhunt_control&0x10 ); /* hstretch */

	draw_text( bitmap );
}
