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

                          -= Fuuki 16 Bit Games (FG-2) =-

                    driver by   Luca Elia (l.elia@tin.it)
                    c.f. Fuuki FG-3


    [ 4 Scrolling Layers ]

                            [ Layer 0 ]     [ Layer 1 ]     [ Layers 2&3 (double-buffered) ]

    Tile Size:              16 x 16 x 4     16 x 16 x 8     8 x 8 x 4
    Layer Size (tiles):     64 x 32         64 x 32         64 x 32

    [ 1024? Zooming Sprites ]

    Sprites are made of 16 x 16 x 4 tiles. Size can vary from 1 to 16
    tiles both horizontally and vertically.
    There is zooming (from full size to half size) and 4 levels of
    priority (wrt layers)

    * Note: the game does hardware assisted raster effects *

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

#include "driver.h"

/* Variables that driver has access to: */

UINT16 *fuuki16_vram_0, *fuuki16_vram_1;
UINT16 *fuuki16_vram_2, *fuuki16_vram_3;
UINT16 *fuuki16_vregs,  *fuuki16_priority, *fuuki16_unknown;


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


                                    Tilemaps

    Offset:     Bits:                   Value:

        0.w                             Code

        2.w     fedc ba98 ---- ----
                ---- ---- 7--- ----     Flip Y
                ---- ---- -6-- ----     Flip X
                ---- ---- --54 3210     Color


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

#define LAYER( _N_ ) \
\
static tilemap *tilemap_##_N_; \
\
static TILE_GET_INFO( get_tile_info_##_N_ ) \
{ \
	UINT16 code = fuuki16_vram_##_N_[ 2 * tile_index + 0 ]; \
	UINT16 attr = fuuki16_vram_##_N_[ 2 * tile_index + 1 ]; \
	SET_TILE_INFO(1 + _N_, code, attr & 0x3f,TILE_FLIPYX( (attr >> 6) & 3 )); \
} \
\
WRITE16_HANDLER( fuuki16_vram_##_N_##_w ) \
{ \
	COMBINE_DATA(&fuuki16_vram_##_N_[offset]); \
	tilemap_mark_tile_dirty(tilemap_##_N_,offset/2); \
}

LAYER( 0 )
LAYER( 1 )
LAYER( 2 )
LAYER( 3 )


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


                            Video Hardware Init


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

/* Not used atm, seems to be fine without clearing pens? */
#if 0
PALETTE_INIT( fuuki16 )
{
	int pen;

	/* The game does not initialise the palette at startup. It should
       be totally black */
	for (pen = 0; pen < machine->config->total_colors; pen++)
		palette_set_color(machine,pen,MAKE_RGB(0,0,0));
}
#endif

VIDEO_START( fuuki16 )
{
	tilemap_0 = tilemap_create(	machine, get_tile_info_0, tilemap_scan_rows,
								 16, 16, 64,32);

	tilemap_1 = tilemap_create(	machine, get_tile_info_1, tilemap_scan_rows,
								 16, 16, 64,32);

	tilemap_2 = tilemap_create(	machine, get_tile_info_2, tilemap_scan_rows,
								  8,  8, 64,32);

	tilemap_3 = tilemap_create(	machine, get_tile_info_3, tilemap_scan_rows,
								  8,  8, 64,32);

	tilemap_set_transparent_pen(tilemap_0,0x0f);	// 4 bits
	tilemap_set_transparent_pen(tilemap_1,0xff);	// 8 bits
	tilemap_set_transparent_pen(tilemap_2,0x0f);	// 4 bits
	tilemap_set_transparent_pen(tilemap_3,0x0f);	// 4 bits

	machine->gfx[2]->color_granularity=16; /* 256 colour tiles with palette selectable on 16 colour boundaries */
}


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


                                Sprites Drawing

    Offset:     Bits:                   Value:

        0.w     fedc ---- ---- ----     Number Of Tiles Along X - 1
                ---- b--- ---- ----     Flip X
                ---- -a-- ---- ----     1 = Don't Draw This Sprite
                ---- --98 7654 3210     X (Signed)

        2.w     fedc ---- ---- ----     Number Of Tiles Along Y - 1
                ---- b--- ---- ----     Flip Y
                ---- -a-- ---- ----
                ---- --98 7654 3210     Y (Signed)

        4.w     fedc ---- ---- ----     Zoom X ($0 = Full Size, $F = Half Size)
                ---- ba98 ---- ----     Zoom Y ""
                ---- ---- 76-- ----     Priority
                ---- ---- --54 3210     Color

        6.w                             Code


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

static void draw_sprites(const device_config *screen, bitmap_t *bitmap, const rectangle *cliprect)
{
	int offs;

	const rectangle *visarea = video_screen_get_visible_area(screen);
	int max_x =	visarea->max_x+1;
	int max_y =	visarea->max_y+1;

	/* Draw them backwards, for pdrawgfx */
	for ( offs = (spriteram_size-8)/2; offs >=0; offs -= 8/2 )
	{
		int x, y, xstart, ystart, xend, yend, xinc, yinc;
		int xnum, ynum, xzoom, yzoom, flipx, flipy;
		int pri_mask;

		int sx			=		spriteram16[offs + 0];
		int sy			=		spriteram16[offs + 1];
		int attr		=		spriteram16[offs + 2];
		int code		=		spriteram16[offs + 3];

		if (sx & 0x400)		continue;

		flipx		=		sx & 0x0800;
		flipy		=		sy & 0x0800;

		xnum		=		((sx >> 12) & 0xf) + 1;
		ynum		=		((sy >> 12) & 0xf) + 1;

		xzoom		=		16*8 - (8 * ((attr >> 12) & 0xf))/2;
		yzoom		=		16*8 - (8 * ((attr >>  8) & 0xf))/2;

		switch( (attr >> 6) & 3 )
		{
			case 3:		pri_mask = 0xf0|0xcc|0xaa;	break;	// behind all layers
			case 2:		pri_mask = 0xf0|0xcc;		break;	// behind fg + middle layer
			case 1:		pri_mask = 0xf0;			break;	// behind fg layer
			case 0:
			default:	pri_mask = 0;						// above all
		}

		sx = (sx & 0x1ff) - (sx & 0x200);
		sy = (sy & 0x1ff) - (sy & 0x200);

		if (flip_screen_get(screen->machine))
		{	flipx = !flipx;		sx = max_x - sx - xnum * 16;
			flipy = !flipy;		sy = max_y - sy - ynum * 16;	}

		if (flipx)	{ xstart = xnum-1;  xend = -1;    xinc = -1; }
		else		{ xstart = 0;       xend = xnum;  xinc = +1; }

		if (flipy)	{ ystart = ynum-1;  yend = -1;    yinc = -1; }
		else		{ ystart = 0;       yend = ynum;  yinc = +1; }

		for (y = ystart; y != yend; y += yinc)
		{
			for (x = xstart; x != xend; x += xinc)
			{
				if (xzoom == (16*8) && yzoom == (16*8))
					pdrawgfx(		bitmap,screen->machine->gfx[0],
									code++,
									attr & 0x3f,
									flipx, flipy,
									sx + x * 16, sy + y * 16,
									cliprect,TRANSPARENCY_PEN,15,
									pri_mask	);
				else
					pdrawgfxzoom(	bitmap,screen->machine->gfx[0],
									code++,
									attr & 0x3f,
									flipx, flipy,
									sx + (x * xzoom) / 8, sy + (y * yzoom) / 8,
									cliprect,TRANSPARENCY_PEN,15,
									(0x10000/0x10/8) * (xzoom + 8),(0x10000/0x10/8) * (yzoom + 8),	// nearest greater integer value to avoid holes
									pri_mask	);
			}
		}

#ifdef MAME_DEBUG
#if 0
if (input_code_pressed(KEYCODE_X))
{	/* Display some info on each sprite */
	char buf[40];
	sprintf(buf, "%Xx%X %X",xnum,ynum,(attr>>6)&3);
	ui_draw_text(buf, sx, sy);
}
#endif
#endif
	}
}


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


                                Screen Drawing

    Video Registers (fuuki16_vregs):

        00.w        Layer 0 Scroll Y
        02.w        Layer 0 Scroll X
        04.w        Layer 1 Scroll Y
        06.w        Layer 1 Scroll X
        08.w        Layer 2 Scroll Y
        0a.w        Layer 2 Scroll X
        0c.w        Layers Y Offset
        0e.w        Layers X Offset

        10-1a.w     ? 0
        1c.w        Trigger a level 5 irq on this raster line
        1e.w        ? $3390/$3393 (Flip Screen Off/On), $0040 is buffer for tilemap 2 or 3

    Priority Register (fuuki16_priority):

        fedc ba98 7654 3---
        ---- ---- ---- -210     Layer Order


    Unknown Registers (fuuki16_unknown):

        00.w        ? $0200/$0201   (Flip Screen Off/On)
        02.w        ? $f300/$0330

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

/* Wrapper to handle bg and bg2 ttogether */
static void fuuki16_draw_layer(bitmap_t *bitmap, const rectangle *cliprect, int i, int flag, int pri)
{
	int buffer = (fuuki16_vregs[0x1e/2] & 0x40);

	switch( i )
	{
		case 2:	if (buffer)	tilemap_draw(bitmap,cliprect,tilemap_3,flag,pri);
				else		tilemap_draw(bitmap,cliprect,tilemap_2,flag,pri);
				return;
		case 1:	tilemap_draw(bitmap,cliprect,tilemap_1,flag,pri);
				return;
		case 0:	tilemap_draw(bitmap,cliprect,tilemap_0,flag,pri);
				return;
	}
}

VIDEO_UPDATE( fuuki16 )
{
	UINT16 layer0_scrollx, layer0_scrolly;
	UINT16 layer1_scrollx, layer1_scrolly;
	UINT16 layer2_scrollx, layer2_scrolly;
	UINT16 scrollx_offs,   scrolly_offs;

	/*
    It's not independant bits causing layers to switch, that wouldn't make sense with 3 bits.
    See fuukifg3 for more justification
    */

	int tm_back, tm_middle, tm_front;
	static const int pri_table[6][3] = {
		{ 0, 1, 2 },
		{ 0, 2, 1 },
		{ 1, 0, 2 },
		{ 1, 2, 0 },
		{ 2, 0, 1 },
		{ 2, 1, 0 }};

	tm_front  = pri_table[ fuuki16_priority[0] & 0x0f ][0];
	tm_middle = pri_table[ fuuki16_priority[0] & 0x0f ][1];
	tm_back   = pri_table[ fuuki16_priority[0] & 0x0f ][2];

	flip_screen_set(screen->machine, fuuki16_vregs[0x1e/2] & 1);

	/* Layers scrolling */

	scrolly_offs = fuuki16_vregs[0xc/2] - (flip_screen_get(screen->machine) ? 0x103 : 0x1f3);
	scrollx_offs = fuuki16_vregs[0xe/2] - (flip_screen_get(screen->machine) ? 0x2a7 : 0x3f6);

	layer0_scrolly = fuuki16_vregs[0x0/2] + scrolly_offs;
	layer0_scrollx = fuuki16_vregs[0x2/2] + scrollx_offs;
	layer1_scrolly = fuuki16_vregs[0x4/2] + scrolly_offs;
	layer1_scrollx = fuuki16_vregs[0x6/2] + scrollx_offs;

	layer2_scrolly = fuuki16_vregs[0x8/2];
	layer2_scrollx = fuuki16_vregs[0xa/2];

	tilemap_set_scrollx(tilemap_0, 0, layer0_scrollx);
	tilemap_set_scrolly(tilemap_0, 0, layer0_scrolly);
	tilemap_set_scrollx(tilemap_1, 0, layer1_scrollx);
	tilemap_set_scrolly(tilemap_1, 0, layer1_scrolly);

	tilemap_set_scrollx(tilemap_2, 0, layer2_scrollx + 0x10);
	tilemap_set_scrolly(tilemap_2, 0, layer2_scrolly /*+ 0x02*/);
	tilemap_set_scrollx(tilemap_3, 0, layer2_scrollx + 0x10);
	tilemap_set_scrolly(tilemap_3, 0, layer2_scrolly /*+ 0x02*/);

	/* The backmost tilemap decides the background color(s) but sprites can
       go below the opaque pixels of that tilemap. We thus need to mark the
       transparent pixels of this layer with a different priority value */
//  fuuki16_draw_layer(bitmap,cliprect, tm_back,  TILEMAP_DRAW_OPAQUE, 0);

	/* Actually, bg colour is simply the last pen i.e. 0x1fff -pjp */
	bitmap_fill(bitmap,cliprect,(0x800*4)-1);
	bitmap_fill(priority_bitmap,cliprect,0);

	fuuki16_draw_layer(bitmap,cliprect, tm_back,   0, 1);
	fuuki16_draw_layer(bitmap,cliprect, tm_middle, 0, 2);
	fuuki16_draw_layer(bitmap,cliprect, tm_front,  0, 4);

	draw_sprites(screen, bitmap, cliprect);

	return 0;
}
