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

                            -= Kaneko 16 Bit Games =-

                    driver by   Luca Elia (l.elia@tin.it)


Note:   if MAME_DEBUG is defined, pressing:

        Q  with  X/C/V/B/ Z   shows Layer 0 (tiles with priority 0/1/2/3/ All)
        W  with  X/C/V/B/ Z   shows Layer 1 (tiles with priority 0/1/2/3/ All)
        E  with  X/C/V/B/ Z   shows Layer 2 (tiles with priority 0/1/2/3/ All)
        R  with  X/C/V/B/ Z   shows Layer 3 (tiles with priority 0/1/2/3/ All)
        A  with  X/C/V/B/ Z   shows Sprites (tiles with priority 0/1/2/3/ All)

        Keys can be used together!

    [ 1 High Color Layer ]

        In ROM  (Optional)

    [ Scrolling Layers ]

        Each VIEW2 chip generates 2 layers. Up to 2 chips are used
        (4 layers)

        Layer Size:             512 x 512
        Tiles:                  16 x 16 x 4

        Line scroll is supported by the chip: each layer has RAM
        for 512 horizontal scroll offsets (one per tilemap line)
        that are added to the global scroll values.
        See e.g. blazeon (2nd demo level), mgcrystl, sandscrp.

    [ 1024 Sprites ]

        Sprites are 16 x 16 x 4 in the older games, 16 x 16 x 8 in
        gtmr & gtmr2.
        Sprites types 0 and 2 can also have a simple effect keeping
        sprites on the screen


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

#include "driver.h"
#include "kaneko16.h"


UINT16 kaneko16_disp_enable = 1; // default enabled for games not using it


tilemap *kaneko16_tmap_0, *kaneko16_tmap_1;
tilemap *kaneko16_tmap_2, *kaneko16_tmap_3;
UINT16 *kaneko16_vram_0,    *kaneko16_vram_1,    *kaneko16_layers_0_regs;
UINT16 *kaneko16_vscroll_0, *kaneko16_vscroll_1;
UINT16 *kaneko16_vram_2,    *kaneko16_vram_3,    *kaneko16_layers_1_regs;
UINT16 *kaneko16_vscroll_2, *kaneko16_vscroll_3;


int kaneko16_sprite_type;
int kaneko16_keep_sprites = 0; // default disabled for games not using it
UINT16 kaneko16_sprite_xoffs, kaneko16_sprite_flipx;
UINT16 kaneko16_sprite_yoffs, kaneko16_sprite_flipy;
UINT16 *kaneko16_sprites_regs;


UINT16 *kaneko16_bg15_select, *kaneko16_bg15_reg;
static mame_bitmap *kaneko16_bg15_bitmap;
static mame_bitmap *sprites_bitmap; /* bitmap used for to keep sprites on screen (mgcrystl 1st boss) */

struct tempsprite
{
	int code,color;
	int x,y;
	int xoffs,yoffs;
	int flipx,flipy;
	int priority;
};

static struct
{
	struct tempsprite *first_sprite;
}	spritelist;


kaneko16_priority_t kaneko16_priority;


WRITE16_HANDLER( kaneko16_display_enable )
{
	COMBINE_DATA(&kaneko16_disp_enable);
}

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

                        Callbacks for the TileMap code

                              [ Tiles Format ]

Offset:

0000.w          fedc b--- ---- ----     unused?
                ---- -a9- ---- ----     High Priority (vs Sprites)
                ---- ---8 ---- ----     High Priority (vs Tiles)
                ---- ---- 7654 32--     Color
                ---- ---- ---- --1-     Flip X
                ---- ---- ---- ---0     Flip Y

0002.w                                  Code

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

#define KANEKO16_LAYER(_N_) \
static void get_tile_info_##_N_(int tile_index) \
{ \
	UINT16 code_hi = kaneko16_vram_##_N_[ 2 * tile_index + 0]; \
	UINT16 code_lo = kaneko16_vram_##_N_[ 2 * tile_index + 1]; \
	SET_TILE_INFO(1 + _N_/2, code_lo, (code_hi >> 2) & 0x3f, TILE_FLIPXY( code_hi & 3 )); \
	tile_info.priority	=	(code_hi >> 8) & 7; \
} \
\
WRITE16_HANDLER( kaneko16_vram_##_N_##_w ) \
{ \
	UINT16 old_data	=	kaneko16_vram_##_N_[offset]; \
	UINT16 new_data	=	COMBINE_DATA(&kaneko16_vram_##_N_[offset]); \
	if (old_data != new_data)	tilemap_mark_tile_dirty(kaneko16_tmap_##_N_, offset/2); \
}


KANEKO16_LAYER(0)
KANEKO16_LAYER(1)
KANEKO16_LAYER(2)
KANEKO16_LAYER(3)

VIDEO_START( kaneko16_sprites )
{
	/* 0x400 sprites max */
	spritelist.first_sprite = (struct tempsprite *)auto_malloc(0x400 * sizeof(spritelist.first_sprite[0]));

	return 0;
}

VIDEO_START( kaneko16_1xVIEW2 )
{
	if (	video_start_kaneko16_sprites(machine)	)
		return 1;

	kaneko16_tmap_0 = tilemap_create(	get_tile_info_0, tilemap_scan_rows,
										TILEMAP_TRANSPARENT, 16,16, 0x20,0x20	);
	kaneko16_tmap_1 = tilemap_create(	get_tile_info_1, tilemap_scan_rows,
										TILEMAP_TRANSPARENT, 16,16, 0x20,0x20	);

	kaneko16_tmap_2 = 0;

	kaneko16_tmap_3 = 0;

	sprites_bitmap = auto_bitmap_alloc(machine->screen[0].width,machine->screen[0].height,machine->screen[0].format);

	{
		int dx, xdim = machine->screen[0].width;
		int dy, ydim = machine->screen[0].height;

		switch (xdim)
		{
			case 320:	dx = 0x33;	break;
			case 256:	dx = 0x5b;	break;
			default:	dx = 0;
		}
		switch (machine->screen[0].visarea.max_y - machine->screen[0].visarea.min_y + 1)
		{
			case 240- 8:	dy = +0x08;	break;	/* blazeon */
			case 240-16:	dy = -0x08;	break;	/* berlwall, bakubrk */
			default:		dy = 0;
		}

		tilemap_set_scrolldx( kaneko16_tmap_0, -dx,		xdim + dx -1        );
		tilemap_set_scrolldx( kaneko16_tmap_1, -(dx+2),	xdim + (dx + 2) - 1 );

		tilemap_set_scrolldy( kaneko16_tmap_0, -dy,		ydim + dy -1 );
		tilemap_set_scrolldy( kaneko16_tmap_1, -dy,		ydim + dy -1 );

		tilemap_set_transparent_pen(kaneko16_tmap_0, 0);
		tilemap_set_transparent_pen(kaneko16_tmap_1, 0);

		tilemap_set_scroll_rows(kaneko16_tmap_0, 0x200);	// Line Scroll
		tilemap_set_scroll_rows(kaneko16_tmap_1, 0x200);

		return 0;
	}
}

VIDEO_START( kaneko16_2xVIEW2 )
{
	if (	video_start_kaneko16_1xVIEW2(machine)	)
		return 1;

	kaneko16_tmap_2 = tilemap_create(	get_tile_info_2, tilemap_scan_rows,
										TILEMAP_TRANSPARENT, 16,16, 0x20,0x20	);
	kaneko16_tmap_3 = tilemap_create(	get_tile_info_3, tilemap_scan_rows,
										TILEMAP_TRANSPARENT, 16,16, 0x20,0x20	);

	{
		int dx, xdim = machine->screen[0].width;
		int dy, ydim = machine->screen[0].height;

		switch (xdim)
		{
			case 320:	dx = 0x33;	break;
			case 256:	dx = 0x5b;	break;
			default:	dx = 0;
		}
		switch (machine->screen[0].visarea.max_y - machine->screen[0].visarea.min_y + 1)
		{
			case 240- 8:	dy = +0x08;	break;
			case 240-16:	dy = -0x08;	break;
			default:		dy = 0;
		}

		tilemap_set_scrolldx( kaneko16_tmap_2, -dx,		xdim + dx -1        );
		tilemap_set_scrolldx( kaneko16_tmap_3, -(dx+2),	xdim + (dx + 2) - 1 );

		tilemap_set_scrolldy( kaneko16_tmap_2, -dy,		ydim + dy -1 );
		tilemap_set_scrolldy( kaneko16_tmap_3, -dy,		ydim + dy -1 );

		tilemap_set_transparent_pen(kaneko16_tmap_2, 0);
		tilemap_set_transparent_pen(kaneko16_tmap_3, 0);

		tilemap_set_scroll_rows(kaneko16_tmap_2, 0x200);	// Line Scroll
		tilemap_set_scroll_rows(kaneko16_tmap_3, 0x200);

		return 0;
	}
}

VIDEO_START( sandscrp_1xVIEW2 )
{
	if (	video_start_kaneko16_1xVIEW2(machine)	)
		return 1;

	tilemap_set_scrolldy( kaneko16_tmap_0, 0, 256 - 1 );
	tilemap_set_scrolldy( kaneko16_tmap_1, 0, 256 - 1 );
	return 0;
}


/* Berlwall has an additional hi-color background */

PALETTE_INIT( berlwall )
{
	int i;

	/* first 2048 colors are dynamic */

	/* initialize 555 RGB lookup */
	for (i = 0; i < 32768; i++)
		palette_set_color(machine,2048 + i,pal5bit(i >> 5),pal5bit(i >> 10),pal5bit(i >> 0));
}

VIDEO_START( berlwall )
{
	int sx, x,y;
	unsigned char *RAM	=	memory_region(REGION_GFX3);

	/* Render the hi-color static backgrounds held in the ROMs */

	kaneko16_bg15_bitmap = auto_bitmap_alloc(256 * 32, 256 * 1, BITMAP_FORMAT_INDEXED16);

/*
    8aba is used as background color
    8aba/2 = 455d = 10001 01010 11101 = $11 $0a $1d
*/

	for (sx = 0 ; sx < 32 ; sx++)	// horizontal screens
	 for (x = 0 ; x < 256 ; x++)	// horizontal pixels
	  for (y = 0 ; y < 256 ; y++)	// vertical pixels
	  {
			int addr  = sx * (256 * 256) + x + y * 256;
			int data = RAM[addr * 2 + 0] * 256 + RAM[addr * 2 + 1];
			int r,g,b;

			r = (data & 0x07c0) >>  6;
			g = (data & 0xf800) >> 11;
			b = (data & 0x003e) >>  1;

			/* apply a simple decryption */
			r ^= 0x09;

			if (~g & 0x08) g ^= 0x10;
			g = (g - 1) & 0x1f;		/* decrease with wraparound */

			b ^= 0x03;
			if (~b & 0x08) b ^= 0x10;
			b = (b + 2) & 0x1f;		/* increase with wraparound */

			/* kludge to fix the rollercoaster picture */
			if ((r & 0x10) && (b & 0x10))
				g = (g - 1) & 0x1f;		/* decrease with wraparound */

			plot_pixel( kaneko16_bg15_bitmap,
						sx * 256 + x, y,
						machine->pens[2048 + ((g << 10) | (r << 5) | b)] );
	  }

	return video_start_kaneko16_1xVIEW2(machine);
}


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

                                Sprites Drawing

    Sprite data is layed out in RAM in different ways for different games
    (type 0,1,2,etc.). This basically involves the bits in the attribute
    word to be shuffled around and/or the words being in different order.

    Each sprite is always stuffed in 4 words. There may be some extra
    padding words though (e.g. type 2 sprites are like type 0 but the
    data is held in the last 8 bytes of every 16). Examples are:

    Type 0: shogwarr, blazeon, bakubrkr.
    Type 1: gtmr.
    Type 2: berlwall

Offset:         Format:                     Value:

0000.w          Attribute (type 0 & 2)

                    f--- ---- ---- ----     Multisprite: Use Latched Code + 1
                    -e-- ---- ---- ----     Multisprite: Use Latched Color (And Flip?)
                    --d- ---- ---- ----     Multisprite: Use Latched X,Y As Offsets
                    ---c ba-- ---- ----
                    ---- --9- ---- ----     High Priority (vs FG Tiles Of High Priority)
                    ---- ---8 ---- ----     High Priority (vs BG Tiles Of High Priority)
                    ---- ---- 7654 32--     Color
                    ---- ---- ---- --1-     X Flip
                    ---- ---- ---- ---0     Y Flip

                Attribute (type 1)

                    f--- ---- ---- ----     Multisprite: Use Latched Code + 1
                    -e-- ---- ---- ----     Multisprite: Use Latched Color (And Flip?)
                    --d- ---- ---- ----     Multisprite: Use Latched X,Y As Offsets
                    ---c ba-- ---- ----
                    ---- --9- ---- ----     X Flip
                    ---- ---8 ---- ----     Y Flip
                    ---- ---- 7--- ----     High Priority (vs FG Tiles Of High Priority)
                    ---- ---- -6-- ----     High Priority (vs BG Tiles Of High Priority)
                    ---- ---- --54 3210     Color

0002.w                                      Code
0004.w                                      X Position << 6
0006.w                                      Y Position << 6

    Type 3: sandscrp

Offset:         Format:             Value:

07.b            7654 ----           Color
                ---- 3---
                ---- -2--           Multi Sprite
                ---- --1-           Y (High Bit)
                ---- ---0           X (High Bit)

09.b                                X (Low Bits)

0B.b                                Y (Low Bits)

0D.b                                Code (Low Bits)

0F.b            7--- ----           Flip X
                -6-- ----           Flip Y
                --54 3210           Code (High Bits)

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

#define USE_LATCHED_XY		1
#define USE_LATCHED_CODE	2
#define USE_LATCHED_COLOR	4

int kaneko16_parse_sprite_type012(int i, struct tempsprite *s)
{
	int attr, xoffs, offs;

	if (kaneko16_sprite_type == 2)	offs = i * 16/2 + 0x8/2;
	else							offs = i * 8/2;

	if (offs >= (spriteram_size/2))	return -1;

	attr			=		spriteram16[offs + 0];
	s->code			=		spriteram16[offs + 1];
	s->x			=		spriteram16[offs + 2];
	s->y			=		spriteram16[offs + 3];

	if (kaneko16_sprite_type == 1)
	{
	s->color		=		(attr & 0x003f);
	s->priority		=		(attr & 0x00c0) >> 6;
	s->flipy		=		(attr & 0x0100);
	s->flipx		=		(attr & 0x0200);
	s->code			+=		(s->y & 1) << 16;	// bloodwar
	}
	else
	{
	s->flipy		=		(attr & 0x0001);
	s->flipx		=		(attr & 0x0002);
	s->color		=		(attr & 0x00fc) >> 2;
	s->priority		=		(attr & 0x0300) >> 8;
	}
	xoffs			=		(attr & 0x1800) >> 11;
	s->yoffs		=		kaneko16_sprites_regs[0x10/2 + xoffs*2 + 1];
	s->xoffs		=		kaneko16_sprites_regs[0x10/2 + xoffs*2 + 0];

if (kaneko16_sprite_flipy)
{
	s->yoffs		-=		kaneko16_sprites_regs[0x2/2];
	s->yoffs		-=		Machine->screen[0].visarea.min_y<<6;
}
else
{
	s->yoffs		-=		kaneko16_sprites_regs[0x2/2];
	s->yoffs		+=		Machine->screen[0].visarea.min_y<<6;
}

	return 					( (attr & 0x2000) ? USE_LATCHED_XY    : 0 ) |
							( (attr & 0x4000) ? USE_LATCHED_COLOR : 0 ) |
							( (attr & 0x8000) ? USE_LATCHED_CODE  : 0 ) ;
}


int kaneko16_parse_sprite_type3(int i, struct tempsprite *s)
{
	int attr;

	int offs = i * 16/2;

	if (offs >= (spriteram_size/2))	return -1;

	attr			=		(spriteram16[offs + 0x6/2] & 0xff);
	s->x			=		(spriteram16[offs + 0x8/2] & 0xff);
	s->y			=		(spriteram16[offs + 0xa/2] & 0xff);
	s->code			=		(spriteram16[offs + 0xc/2] & 0xff) +
							(spriteram16[offs + 0xe/2] & 0xff) * 256;

	s->flipy		=		s->code & 0x4000;
	s->flipx		=		s->code & 0x8000;

	s->priority		=		3;	// ?
	s->xoffs		=		0;	// ?
	s->yoffs		=		0;	// ?

	s->x			|=		(attr & 0x01) ? 0xff00 : 0;
	s->y			|=		(attr & 0x02) ? 0xff00 : 0;
	s->x			<<=		6;
	s->y			<<=		6;
	s->color		=		(attr & 0xf0) >> 4;

	return					(attr & 0x04) ? USE_LATCHED_XY : 0;
}

// custom function to draw a single sprite. needed to keep correct sprites - sprites and sprites - tilemaps priorities
static void kaneko16_draw_sprites_custom(mame_bitmap *dest_bmp,const gfx_element *gfx,
		unsigned int code,unsigned int color,int flipx,int flipy,int sx,int sy,
		const rectangle *clip,int priority)
{
	const pen_t *pal = &gfx->colortable[gfx->color_granularity * (color % gfx->total_colors)]; /* ASG 980209 */
	UINT8 *source_base = gfx->gfxdata + (code % gfx->total_elements) * gfx->char_modulo;

	int sprite_screen_height = ((1<<16)*gfx->height+0x8000)>>16;
	int sprite_screen_width = ((1<<16)*gfx->width+0x8000)>>16;

	if (sprite_screen_width && sprite_screen_height)
	{
		/* compute sprite increment per screen pixel */
		int dx = (gfx->width<<16)/sprite_screen_width;
		int dy = (gfx->height<<16)/sprite_screen_height;

		int ex = sx+sprite_screen_width;
		int ey = sy+sprite_screen_height;

		int x_index_base;
		int y_index;

		if( flipx )
		{
			x_index_base = (sprite_screen_width-1)*dx;
			dx = -dx;
		}
		else
		{
			x_index_base = 0;
		}

		if( flipy )
		{
			y_index = (sprite_screen_height-1)*dy;
			dy = -dy;
		}
		else
		{
			y_index = 0;
		}

		if( clip )
		{
			if( sx < clip->min_x)
			{ /* clip left */
				int pixels = clip->min_x-sx;
				sx += pixels;
				x_index_base += pixels*dx;
			}
			if( sy < clip->min_y )
			{ /* clip top */
				int pixels = clip->min_y-sy;
				sy += pixels;
				y_index += pixels*dy;
			}
			/* NS 980211 - fixed incorrect clipping */
			if( ex > clip->max_x+1 )
			{ /* clip right */
				int pixels = ex-clip->max_x-1;
				ex -= pixels;
			}
			if( ey > clip->max_y+1 )
			{ /* clip bottom */
				int pixels = ey-clip->max_y-1;
				ey -= pixels;
			}
		}

		if( ex>sx )
		{ /* skip if inner loop doesn't draw anything */
			int y;

			for( y=sy; y<ey; y++ )
			{
				UINT8 *source = source_base + (y_index>>16) * gfx->line_modulo;
				UINT16 *dest = BITMAP_ADDR16(dest_bmp, y, 0);
				UINT8 *pri = BITMAP_ADDR8(priority_bitmap, y, 0);

				int x, x_index = x_index_base;
				for( x=sx; x<ex; x++ )
				{
					int c = source[x_index>>16];
					if( c != 0 )
					{
						if (pri[x] < priority)
							dest[x] = pal[c];
						pri[x] = 0xff; // mark it "already drawn"
					}
					x_index += dx;
				}

				y_index += dy;
			}
		}
	}
}

/* Build a list of sprites to display & draw them */

void kaneko16_draw_sprites(mame_bitmap *bitmap, const rectangle *cliprect, int pri)
{
	/* Sprites *must* be parsed from the first in RAM to the last,
       because of the multisprite feature. But they *must* be drawn
       from the last in RAM (frontmost) to the firtst in order to
       cope with priorities using pdrawgfx.

       Hence we parse them from first to last and put the result
       in a temp buffer, then draw the buffer's contents from last
       to first. */

	int max	=	(Machine->screen[0].width > 0x100) ? (0x200<<6) : (0x100<<6);

	int i = 0;
	struct tempsprite *s = spritelist.first_sprite;

	/* These values are latched from the last sprite. */
	int x			=	0;
	int y			=	0;
	int code		=	0;
	int color		=	0;
	int priority	=	0;
	int xoffs		=	0;
	int yoffs		=	0;
	int flipx		=	0;
	int flipy		=	0;

	while (1)
	{
		int flags;

		switch( kaneko16_sprite_type )
		{
			case 0:
			case 1:
			case 2:		flags = kaneko16_parse_sprite_type012(i,s);	break;
			case 3:		flags = kaneko16_parse_sprite_type3(i,s);	break;
			default:	flags = -1;
		}

		if (flags == -1)	// End of Sprites
			break;

		if (flags & USE_LATCHED_CODE)
			s->code = ++code;	// Use the latched code + 1 ..
		else
			code = s->code;		// .. or latch this value

		if (flags & USE_LATCHED_COLOR)
		{
			s->color		=	color;
			s->priority		=	priority;
			s->xoffs		=	xoffs;
			s->yoffs		=	yoffs;
			s->flipx		=	flipx;
			s->flipy		=	flipy;
		}
		else
		{
			color		=	s->color;
			priority	=	s->priority;
			xoffs		=	s->xoffs;
			yoffs		=	s->yoffs;
			flipx		=	s->flipx;
			flipy		=	s->flipy;
		}

		if (flags & USE_LATCHED_XY)
		{
			s->x += x;
			s->y += y;
		}
		// Always latch the latest result
		x	=	s->x;
		y	=	s->y;

		/* We can now buffer this sprite */

		s->x	=	s->xoffs + s->x;
		s->y	=	s->yoffs + s->y;

		s->x	+=	kaneko16_sprite_xoffs;
		s->y	+=	kaneko16_sprite_yoffs;

		if (kaneko16_sprite_flipx)	{ s->x = max - s->x - (16<<6);	s->flipx = !s->flipx;	}
		if (kaneko16_sprite_flipy)	{ s->y = max - s->y - (16<<6);	s->flipy = !s->flipy;	}

		s->x		=		( (s->x & 0x7fc0) - (s->x & 0x8000) ) / 0x40;
		s->y		=		( (s->y & 0x7fc0) - (s->y & 0x8000) ) / 0x40;

		i++;
		s++;
	}


	/* Let's finally draw the sprites we buffered, in reverse order
       (for pdrawgfx) */

	for (s--; s >= spritelist.first_sprite; s--)
	{
		int curr_pri = s->priority;

		UINT32 primask = kaneko16_priority.sprite[curr_pri];

		/* You can choose which sprite priorities get displayed (for debug) */
		if ( curr_pri == pri )	continue;

		kaneko16_draw_sprites_custom(	bitmap,Machine->gfx[0],
										s->code,
										s->color,
										s->flipx, s->flipy,
										s->x, s->y,
										cliprect,
										primask );

		// wrap around x for sandscrp
		if (kaneko16_sprite_type == 3)
			kaneko16_draw_sprites_custom(	bitmap,Machine->gfx[0],
											s->code,
											s->color,
											s->flipx, s->flipy,
											s->x + 512, s->y,
											cliprect,
											primask );
#ifdef MAME_DEBUG
#if 0
if (code_pressed(KEYCODE_Z))
{	/* Display some info on each sprite */
	char buf[10];
	sprintf(buf, "%X",s->priority);
	ui_draw_text(buf, s->x, s->y);
}
#endif
#endif
	}
}



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


                            Sprites Registers

    Offset:         Format:                     Value:

    0000.w          f--- ---- ---- ----         Sprites Disable?? (see blazeon)
                    -edc ba98 7654 3---
                    ---- ---- ---- -2--         Keep sprites on screen (only sprites types 0 and 2)
                    ---- ---- ---- --1-         Flip X
                    ---- ---- ---- ---0         Flip Y

    0002.w                                      Y Offset << 6 (Global)


    0004..000e.w                                ?


    0010.w                                      X Offset << 6 #0
    0012.w                                      Y Offset << 6 #0

    0014.w                                      X Offset << 6 #1
    0016.w                                      Y Offset << 6 #1

    0018.w                                      X Offset << 6 #2
    001a.w                                      Y Offset << 6 #2

    001c.w                                      X Offset << 6 #3
    001e.w                                      Y Offset << 6 #3

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

/*
[gtmr]

Initial self test:
600000: 4BC0 94C0 4C40 94C0-0404 0002 0000 0000     (Layers 1 regs)
680000: 4BC0 94C0 4C40 94C0-1C1C 0002 0000 0000     (Layers 2 regs)
Race start:
600000: DC00 7D00 DC80 7D00-0404 0002 0000 0000     (Layers 1 regs)
680000: DC00 7D00 DC80 7D00-1C1C 0002 0000 0000     (Layers 2 regs)

[gtmr]
700000: 0040 0000 0001 0180-0000 0000 0000 0000     (Sprites  regs)
700010: 0040 0000 0040 0000-0040 0000 2840 1E00     ; 1,0 .. a1,78
                                                    ; a0*2=screenx/2
                                                    ; 78*2=screeny/2
FLIP ON:
700000: 0043 FFC0 0001 0180-0000 0000 0000 0000     (Sprites  regs)
700010: 2FC0 4400 2FC0 4400-2FC0 4400 57C0 6200     ; bf,110 .. 15f,188
                                                    ; 15f-bf=a0! 188-110=78!

[berlwall]
600000: 48CC 03C0 0001 0100-0000 0000 0000 0000     (Sprites  regs)
600010: 0000 0000 0000 0000-0000 0000 0000 0000
FLIP ON:
600000: 48CF FC00 0001 0100-0000 0000 0000 0000     (Sprites  regs)
600010: 0000 0000 0000 0000-0000 0000 0000 0000

[mgcrystl]
900000: 4FCC 0000 0040 00C0-xxxx 0001 0001 0001     (Sprites  regs)
900010: 0000 FC40 A000 9C40-1E00 1A40 0000 FC40
FLIP ON:
900000: 4FCF 0000 0040 00C0-xxxx 0001 0001 0001     (Sprites  regs)
900010: 0000 0400 A000 A400-1E00 2200 0000 0400     ; +1f<<6 on y
*/

READ16_HANDLER( kaneko16_sprites_regs_r )
{
	return kaneko16_sprites_regs[offset];
}

WRITE16_HANDLER( kaneko16_sprites_regs_w )
{
	UINT16 new_data;

	COMBINE_DATA(&kaneko16_sprites_regs[offset]);
	new_data  = kaneko16_sprites_regs[offset];

	switch (offset)
	{
		case 0:
			if (ACCESSING_LSB)
			{
				kaneko16_sprite_flipx = new_data & 2;
				kaneko16_sprite_flipy = new_data & 1;

				if(kaneko16_sprite_type == 0 || kaneko16_sprite_type == 2)
					kaneko16_keep_sprites = ~new_data & 4;
			}

			break;
	}

//  logerror("CPU #0 PC %06X : Warning, sprites reg %04X <- %04X\n",activecpu_get_pc(),offset*2,data);
}


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

                            Layers Registers


    Offset:         Format:                     Value:

    0000.w                                      FG Scroll X
    0002.w                                      FG Scroll Y

    0004.w                                      BG Scroll X
    0006.w                                      BG Scroll Y

    0008.w          Layers Control

                    fed- ---- ---- ----
                    ---c ---- ---- ----     BG Disable
                    ---- b--- ---- ----     Line Scroll (Always 1 in berlwall & bakubrkr)
                    ---- -a-- ---- ----     ? Always 1 in gtmr     & bakubrkr ?
                    ---- --9- ---- ----     BG Flip X
                    ---- ---8 ---- ----     BG Flip Y

                    ---- ---- 765- ----
                    ---- ---- ---4 ----     FG Disable
                    ---- ---- ---- 3---     Line Scroll (Always 1 in berlwall & bakubrkr)
                    ---- ---- ---- -2--     ? Always 1 in gtmr     & bakubrkr ?
                    ---- ---- ---- --1-     FG Flip X
                    ---- ---- ---- ---0     FG Flip Y

    000a.w                                      ? always 0x0002 ?

There are more!

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

/*  [gtmr]

    car select screen scroll values:
    Flipscreen off:
        $6x0000: $72c0 ; $fbc0 ; 7340 ; 0
        $72c0/$40 = $1cb = $200-$35 /   $7340/$40 = $1cd = $1cb+2

        $fbc0/$40 = -$11

    Flipscreen on:
        $6x0000: $5d00 ; $3780 ; $5c80 ; $3bc0
        $5d00/$40 = $174 = $200-$8c /   $5c80/$40 = $172 = $174-2

        $3780/$40 = $de /   $3bc0/$40 = $ef

*/

WRITE16_HANDLER( kaneko16_layers_0_regs_w )
{
	COMBINE_DATA(&kaneko16_layers_0_regs[offset]);
}

WRITE16_HANDLER( kaneko16_layers_1_regs_w )
{
	COMBINE_DATA(&kaneko16_layers_1_regs[offset]);
}




/* Select the high color background image (out of 32 in the ROMs) */
READ16_HANDLER( kaneko16_bg15_select_r )
{
	return kaneko16_bg15_select[0];
}
WRITE16_HANDLER( kaneko16_bg15_select_w )
{
	COMBINE_DATA(&kaneko16_bg15_select[0]);
}

/* ? */
READ16_HANDLER( kaneko16_bg15_reg_r )
{
	return kaneko16_bg15_reg[0];
}
WRITE16_HANDLER( kaneko16_bg15_reg_w )
{
	COMBINE_DATA(&kaneko16_bg15_reg[0]);
}




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


                                Screen Drawing


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

VIDEO_UPDATE( kaneko16 )
{
	int layers_flip_0, layers_flip_1 = 0;
	int layers_ctrl = -1;
	int i,flag;

	UINT16 layer0_scrollx, layer0_scrolly;
	UINT16 layer1_scrollx, layer1_scrolly;

	layers_flip_0 = kaneko16_layers_0_regs[ 4 ];
	if (kaneko16_tmap_2)
	{
	layers_flip_1 = kaneko16_layers_1_regs[ 4 ];
	}

	/* Enable layers */
	tilemap_set_enable(kaneko16_tmap_0, ~layers_flip_0 & 0x1000);
	tilemap_set_enable(kaneko16_tmap_1, ~layers_flip_0 & 0x0010);
	if (kaneko16_tmap_2)
	{
	tilemap_set_enable(kaneko16_tmap_2, ~layers_flip_1 & 0x1000);
	tilemap_set_enable(kaneko16_tmap_3, ~layers_flip_1 & 0x0010);
	}

	/* Flip layers */
	tilemap_set_flip(kaneko16_tmap_0,	((layers_flip_0 & 0x0100) ? TILEMAP_FLIPY : 0) |
								 		((layers_flip_0 & 0x0200) ? TILEMAP_FLIPX : 0) );
	tilemap_set_flip(kaneko16_tmap_1,	((layers_flip_0 & 0x0100) ? TILEMAP_FLIPY : 0) |
								 		((layers_flip_0 & 0x0200) ? TILEMAP_FLIPX : 0) );
	if (kaneko16_tmap_2)
	{
	tilemap_set_flip(kaneko16_tmap_2,	((layers_flip_1 & 0x0100) ? TILEMAP_FLIPY : 0) |
								 		((layers_flip_1 & 0x0200) ? TILEMAP_FLIPX : 0) );
	tilemap_set_flip(kaneko16_tmap_3,	((layers_flip_1 & 0x0100) ? TILEMAP_FLIPY : 0) |
								 		((layers_flip_1 & 0x0200) ? TILEMAP_FLIPX : 0) );
	}

	/* Scroll layers */
	layer0_scrollx		=	kaneko16_layers_0_regs[ 2 ];
	layer0_scrolly		=	kaneko16_layers_0_regs[ 3 ] >> 6;
	layer1_scrollx		=	kaneko16_layers_0_regs[ 0 ];
	layer1_scrolly		=	kaneko16_layers_0_regs[ 1 ] >> 6;

	tilemap_set_scrolly(kaneko16_tmap_0,0,layer0_scrolly);
	tilemap_set_scrolly(kaneko16_tmap_1,0,layer1_scrolly);

	for (i=0; i<0x200; i++)
	{
		UINT16 scroll;
		scroll = (layers_flip_0 & 0x0800) ? kaneko16_vscroll_0[i] : 0;
		tilemap_set_scrollx(kaneko16_tmap_0,i,(layer0_scrollx + scroll) >> 6 );
		scroll = (layers_flip_0 & 0x0008) ? kaneko16_vscroll_1[i] : 0;
		tilemap_set_scrollx(kaneko16_tmap_1,i,(layer1_scrollx + scroll) >> 6 );
	}

	if (kaneko16_tmap_2)
	{
	layer0_scrollx		=	kaneko16_layers_1_regs[ 2 ];
	layer0_scrolly		=	kaneko16_layers_1_regs[ 3 ] >> 6;
	layer1_scrollx		=	kaneko16_layers_1_regs[ 0 ];
	layer1_scrolly		=	kaneko16_layers_1_regs[ 1 ] >> 6;

	tilemap_set_scrolly(kaneko16_tmap_2,0,layer0_scrolly);
	tilemap_set_scrolly(kaneko16_tmap_3,0,layer1_scrolly);

	for (i=0; i<0x200; i++)
	{
		UINT16 scroll;
		scroll = (layers_flip_1 & 0x0800) ? kaneko16_vscroll_2[i] : 0;
		tilemap_set_scrollx(kaneko16_tmap_2,i,(layer0_scrollx + scroll) >> 6 );
		scroll = (layers_flip_1 & 0x0008) ? kaneko16_vscroll_3[i] : 0;
		tilemap_set_scrollx(kaneko16_tmap_3,i,(layer1_scrollx + scroll) >> 6 );
	}
	}

#ifdef MAME_DEBUG
if ( code_pressed(KEYCODE_Z) ||
	 code_pressed(KEYCODE_X) || code_pressed(KEYCODE_C) ||
     code_pressed(KEYCODE_V) || code_pressed(KEYCODE_B) )
{	int msk = 0, val = 0;

	if (code_pressed(KEYCODE_X))	val = 1;	// priority 0 only
	if (code_pressed(KEYCODE_C))	val = 2;	// ""       1
	if (code_pressed(KEYCODE_V))	val = 4;	// ""       2
	if (code_pressed(KEYCODE_B))	val = 8;	// ""       3

	if (code_pressed(KEYCODE_Z))	val = 1|2|4|8;	// All of the above priorities

	if (code_pressed(KEYCODE_Q))	msk |= val << 0;	// for tmap 0
	if (code_pressed(KEYCODE_W))	msk |= val << 4;	// ""       1
	if (code_pressed(KEYCODE_E))	msk |= val << 8;	// ""       2
	if (code_pressed(KEYCODE_R))	msk |= val << 12;	// ""       3
	if (code_pressed(KEYCODE_A))	msk |= val << 16;	// for sprites
	if (msk != 0) layers_ctrl &= msk;

#if 0
	popmessage(
		"%04X %04X %04X %04X %04X %04X %04X %04X - %04X %04X %04X %04X %04X %04X %04X %04X",
		kaneko16_layers_0_regs[0x0],kaneko16_layers_0_regs[0x1],
		kaneko16_layers_0_regs[0x2],kaneko16_layers_0_regs[0x3],
		kaneko16_layers_0_regs[0x4],kaneko16_layers_0_regs[0x5],
		kaneko16_layers_0_regs[0x6],kaneko16_layers_0_regs[0x7],

		kaneko16_layers_0_regs[0x8],kaneko16_layers_0_regs[0x9],
		kaneko16_layers_0_regs[0xa],kaneko16_layers_0_regs[0xb],
		kaneko16_layers_0_regs[0xc],kaneko16_layers_0_regs[0xd],
		kaneko16_layers_0_regs[0xe],kaneko16_layers_0_regs[0xf]	);
#endif
}
#endif

	flag = TILEMAP_IGNORE_TRANSPARENCY;

	/* Draw the high colour bg layer first, if any */

	if (kaneko16_bg15_bitmap)
	{
		int select	=	kaneko16_bg15_select[ 0 ];
//      int reg     =   kaneko16_bg15_reg[ 0 ];
		int flip	=	select & 0x20;
		int sx, sy;

		if (flip)	select ^= 0x1f;

		sx		=	(select & 0x1f) * 256;
		sy		=	0;

		copybitmap(
			bitmap, kaneko16_bg15_bitmap,
			flip, flip,
			-sx, -sy,
			cliprect, TRANSPARENCY_NONE,0 );

		flag = 0;
	}

	if (flag!=0)
	{
		if(kaneko16_sprite_type == 1)
			fillbitmap(bitmap,Machine->pens[0x7f00],cliprect);
		else
			/* Fill the bitmap with pen 0. This is wrong, but will work most of
            the times. To do it right, each pixel should be drawn with pen 0
            of the bottomost tile that covers it (which is pretty tricky to do) */
			fillbitmap(bitmap,Machine->pens[0],cliprect);
	}

	fillbitmap(priority_bitmap,0,cliprect);

	if (!kaneko16_disp_enable) return 0;

	for ( i = 0; i < 8; i++ )
	{
		tilemap_draw_primask(bitmap,cliprect, kaneko16_tmap_0, i, i, 0);
		tilemap_draw_primask(bitmap,cliprect, kaneko16_tmap_1, i, i, 0);

		if (kaneko16_tmap_2)
		{
		tilemap_draw_primask(bitmap,cliprect, kaneko16_tmap_2, i, kaneko16_priority.VIEW2_2_pri ? i : 0, 0);
		tilemap_draw_primask(bitmap,cliprect, kaneko16_tmap_3, i, kaneko16_priority.VIEW2_2_pri ? i : 0, 0);
		}
	}

	/* Sprites last (rendered with pdrawgfx, so they can slip
       in between the layers) */

	if (layers_ctrl & (0xf<<16))
	{
		if(kaneko16_keep_sprites)
		{
			/* keep sprites on screen */
			kaneko16_draw_sprites(sprites_bitmap,cliprect, (layers_ctrl >> 16) & 0xf);
			copybitmap(bitmap,sprites_bitmap,0,0,0,0,cliprect,TRANSPARENCY_PEN,0);
		}
		else
		{
			fillbitmap(sprites_bitmap,Machine->pens[0],cliprect);
			kaneko16_draw_sprites(bitmap,cliprect, (layers_ctrl >> 16) & 0xf);
		}
	}
	return 0;
}
