/*

    Konami Twin16 Hardware - Video

    TODO:

    - convert background to tilemap
    - clean up sprite drawing
    - sprite-background priorities
    - sprite lag in devilw
    - sprite Y axis lag in vulcan
    - add shadow sprites (alpha blending) to sprites in at least devilw

*/

#include "driver.h"
#include "includes/twin16.h"

static int need_process_spriteram;
static UINT16 gfx_bank;
static UINT16 scrollx[3], scrolly[3];
static UINT16 video_register;

enum
{
	TWIN16_SCREEN_FLIPY		= 0x01,	/* ? breaks devils world text layer */
	TWIN16_SCREEN_FLIPX		= 0x02,	/* confirmed: Hard Puncher Intro */
	TWIN16_UNKNOWN1			= 0x04,	/* ?Hard Puncher uses this */
	TWIN16_PLANE_ORDER		= 0x08,	/* confirmed: Devil Worlds */
	TWIN16_TILE_FLIPY		= 0x20	/* confirmed? Vulcan Venture */
};

static tilemap *fg_tilemap;

WRITE16_HANDLER( twin16_videoram2_w )
{
	COMBINE_DATA(&twin16_videoram2[offset]);
	tilemap_mark_tile_dirty(fg_tilemap, offset);
}

WRITE16_HANDLER( twin16_paletteram_word_w )
{ 	// identical to tmnt_paletteram_w
	COMBINE_DATA(paletteram16 + offset);
	offset &= ~1;

	data = ((paletteram16[offset] & 0xff) << 8) | (paletteram16[offset + 1] & 0xff);
	palette_set_color_rgb(space->machine, offset / 2, pal5bit(data >> 0), pal5bit(data >> 5), pal5bit(data >> 10));
}

WRITE16_HANDLER( fround_gfx_bank_w )
{
	COMBINE_DATA(&gfx_bank);
}

WRITE16_HANDLER( twin16_video_register_w )
{
	switch (offset)
	{
		case 0:
			COMBINE_DATA( &video_register );

			flip_screen_x_set(space->machine, video_register & TWIN16_SCREEN_FLIPX);

			if (twin16_custom_video)
				flip_screen_y_set(space->machine, video_register & TWIN16_SCREEN_FLIPY);
			else
				flip_screen_y_set(space->machine, ~video_register & TWIN16_SCREEN_FLIPY);

			break;

		case 1: COMBINE_DATA( &scrollx[0] ); break;
		case 2: COMBINE_DATA( &scrolly[0] ); break;
		case 3: COMBINE_DATA( &scrollx[1] ); break;
		case 4: COMBINE_DATA( &scrolly[1] ); break;
		case 5: COMBINE_DATA( &scrollx[2] ); break;
		case 6: COMBINE_DATA( &scrolly[2] ); break;

		default:
			logerror("unknown video_register write:%d", data );
			break;
	}
}

/* slow slow slow, but it's ok for now */
static void draw_sprite( bitmap_t *bitmap,const UINT16 *pen_data, int pal_base, int xpos, int ypos, int width, int height, int flipx, int flipy, int pri )
{
	int x,y,pval;
	if( xpos>=320 ) xpos -= 65536;
	if( ypos>=256 ) ypos -= 65536;

	if (pri) pval=2; else pval=8;

	for( y=0; y<height; y++ )
	{
		int sy = (flipy)?(ypos+height-1-y):(ypos+y);
		if( sy>=16 && sy<256-16 )
		{
			UINT16 *dest = BITMAP_ADDR16(bitmap, sy, 0);
			UINT8 *pdest = BITMAP_ADDR8(priority_bitmap, sy, 0);

			for( x=0; x<width; x++ )
			{
				int sx = (flipx)?(xpos+width-1-x):(xpos+x);
				if( sx>=0 && sx<320 )
				{
					UINT16 pen = pen_data[x/4];
					switch( x%4 )
					{
						case 0: pen = pen>>12; break;
						case 1: pen = (pen>>8)&0xf; break;
						case 2: pen = (pen>>4)&0xf; break;
						case 3: pen = pen&0xf; break;
					}

					if( pen )
					{
						if(pdest[sx]<pval)
						{
							dest[sx] = pal_base + pen;
						}
						pdest[sx]|=0x10;
					}
				}
			}
		}
		pen_data += width/4;
	}
}

void twin16_spriteram_process( void )
{
	UINT16 dx = scrollx[0];
	UINT16 dy = scrolly[0];

	const UINT16 *source = &spriteram16[0x0000];
	const UINT16 *finish = &spriteram16[0x1800];

	memset( &spriteram16[0x1800], 0, 0x800 );
	while( source<finish )
	{
		UINT16 priority = source[0];
		if( priority & 0x8000 )
		{
			UINT16 *dest = &spriteram16[0x1800 + 4*(priority&0xff)];

			INT32 xpos = (0x10000*source[4])|source[5];
			INT32 ypos = (0x10000*source[6])|source[7];

			UINT16 attributes = source[2]&0x03ff; /* scale,size,color */
			if( priority & 0x0200 ) attributes |= 0x4000;
			/* Todo:  priority & 0x0100 is also used */
			attributes |= 0x8000;

			dest[0] = source[3]; /* gfx data */
			dest[1] = ((xpos>>8) - dx)&0xffff;
			dest[2] = ((ypos>>8) - dy)&0xffff;
			dest[3] = attributes;
		}
		source += 0x50/2;
	}
	need_process_spriteram = 0;
}

/*
 * Sprite Format
 * ----------------------------------
 *
 * Word | Bit(s)           | Use
 * -----+-fedcba9876543210-+----------------
 *   0  | --xxxxxxxxxxxxxx | code
 * -----+------------------+
 *   1  | -------xxxxxxxxx | ypos
 * -----+------------------+
 *   2  | -------xxxxxxxxx | xpos
 * -----+------------------+
 *   3  | x--------------- | enble
 *   3  | -x-------------- | priority?
 *   3  | ------x--------- | yflip?
 *   3  | -------x-------- | xflip
 *   3  | --------xx------ | height
 *   3  | ----------xx---- | width
 *   3  | ------------xxxx | color

shadow bit?

 */

static void draw_sprites( bitmap_t *bitmap )
{
	int count = 0;

	const UINT16 *source = 0x1800+buffered_spriteram16 + 0x800 - 4;
	const UINT16 *finish = 0x1800+buffered_spriteram16;

	for (; source >= finish; source -= 4)
	{
		UINT16 attributes = source[3];
		UINT16 code = source[0];

		if((code!=0xffff) && (attributes&0x8000))
		{
			int xpos = source[1];
			int ypos = source[2];

			int pal_base = ((attributes&0xf)+0x10)*16;
			int height	= 16<<((attributes>>6)&0x3);
			int width	= 16<<((attributes>>4)&0x3);
			const UINT16 *pen_data = 0;
			int flipy = attributes&0x0200;
			int flipx = attributes&0x0100;

			if( twin16_custom_video == 1 )
			{
				pen_data = twin16_gfx_rom + 0x80000;
			}
			else
			{
				switch( (code>>12)&0x3 )
				{ /* bank select */
					case 0:
					pen_data = twin16_gfx_rom;
					break;

					case 1:
					pen_data = twin16_gfx_rom + 0x40000;
					break;

					case 2:
					pen_data = twin16_gfx_rom + 0x80000;
					if( code&0x4000 ) pen_data += 0x40000;
					break;

					case 3:
					pen_data = twin16_sprite_gfx_ram;
					break;
				}
				code &= 0xfff;
			}

			/* some code masking */
			if(height == 64 && width == 64)
			{
				code &= ~8; // fixes bad sprites in vulcan ending sequence
			}
			else if(height == 32 && width == 32)
			{
				code &= ~3; // fixes bad sprites in devilw
			}
			else if(height == 32 && width == 16)
			{
				code &= ~1; // fixes bad sprites in devilw
			}
			else if(height == 16 && width == 32)
			{
				code &= ~1; // fixes bad sprites in devilw
			}

			pen_data += code*0x40;

			if( video_register&TWIN16_SCREEN_FLIPY )
			{
				if (ypos>65000) ypos=ypos-65536; /* Bit hacky */
				ypos = 256-ypos-height;
				flipy = !flipy;
			}
			if( video_register&TWIN16_SCREEN_FLIPX )
			{
				if (xpos>65000) xpos=xpos-65536; /* Bit hacky */
				xpos = 320-xpos-width;
				flipx = !flipx;
			}

			//if( sprite_which==count || !input_code_pressed( KEYCODE_B ) )
			draw_sprite( bitmap, pen_data, pal_base, xpos, ypos, width, height, flipx, flipy, (attributes&0x4000) );
		}

		count++;
	}
}

static void draw_layer( bitmap_t *bitmap, int opaque )
{
	const UINT16 *gfx_base;
	const UINT16 *source = videoram16;
	int i, xxor, yxor;
	int bank_table[4];
	int dx, dy, palette;
	int tile_flipx = 0; // video_register&TWIN16_TILE_FLIPX;
	int tile_flipy = video_register&TWIN16_TILE_FLIPY;

	if( ((video_register&TWIN16_PLANE_ORDER)?1:0) != opaque )
	{
		source += 0x1000;
		dx = scrollx[2];
		dy = scrolly[2];
		palette = 1;
	}
	else
	{
		source += 0x0000;
		dx = scrollx[1];
		dy = scrolly[1];
		palette = 0;
	}

	if( twin16_custom_video == 1 )
	{
		gfx_base = twin16_gfx_rom;
		bank_table[3] = (gfx_bank>>(4*3))&0xf;
		bank_table[2] = (gfx_bank>>(4*2))&0xf;
		bank_table[1] = (gfx_bank>>(4*1))&0xf;
		bank_table[0] = (gfx_bank>>(4*0))&0xf;
	}
	else
	{
		gfx_base = twin16_tile_gfx_ram;
		bank_table[0] = 0;
		bank_table[1] = 1;
		bank_table[2] = 2;
		bank_table[3] = 3;
	}

	if( video_register&TWIN16_SCREEN_FLIPX )
	{
		dx = 256-dx-64;
		tile_flipx = !tile_flipx;
	}

	if( video_register&TWIN16_SCREEN_FLIPY )
	{
		dy = 256-dy;
		tile_flipy = !tile_flipy;
	}

	xxor = tile_flipx ? 7 : 0;
	yxor = tile_flipy ? 7 : 0;

	for( i=0; i<64*64; i++ )
	{
		int y1, y2, x1, x2;
		int sx = (i%64)*8;
		int sy = (i/64)*8;
		int xpos,ypos;

		if( video_register&TWIN16_SCREEN_FLIPX ) sx = 63*8 - sx;
		if( video_register&TWIN16_SCREEN_FLIPY ) sy = 63*8 - sy;

		xpos = (sx-dx)&0x1ff;
		ypos = (sy-dy)&0x1ff;
		if( xpos>=320 ) xpos -= 512;
		if( ypos>=256 ) ypos -= 512;

		x1 = MAX(xpos, 0);
		x2 = MIN(xpos+7, bitmap->width-1);
		y1 = MAX(ypos, 0);
		y2 = MIN(ypos+7, bitmap->height-1);

		if (x1 <= x2 && y1 <= y2)
		{
			int code = source[i];
			/*
                xxx-------------    color
                ---xx-----------    tile bank
                -----xxxxxxxxxxx    tile number
            */
			const UINT16 *gfx_data = gfx_base + (code&0x7ff)*16 + bank_table[(code>>11)&0x3]*0x8000;
			int color = (code>>13);
			int pal_base = 16*(0x20+color+8*palette);
			int x, y;

			if( opaque )
			{
				for (y = y1; y <= y2; y++)
				{
					const UINT16 *gfxptr = gfx_data + ((y - ypos) ^ yxor) * 2;
					UINT16 *dest = BITMAP_ADDR16(bitmap, y, 0);
					UINT8 *pdest = BITMAP_ADDR8(priority_bitmap, y, 0);

					for (x = x1; x <= x2; x++)
					{
						int effx = (x - xpos) ^ xxor;
						UINT16 data = gfxptr[effx / 4];
						dest[x] = pal_base + ((data >> 4*(~effx & 3)) & 0x0f);
						pdest[x] |= 1;
					}
				}
			}
			else
			{
				for (y = y1; y <= y2; y++)
				{
					const UINT16 *gfxptr = gfx_data + ((y - ypos) ^ yxor) * 2;
					UINT16 *dest = BITMAP_ADDR16(bitmap, y, 0);
					UINT8 *pdest = BITMAP_ADDR8(priority_bitmap, y, 0);

					for (x = x1; x <= x2; x++)
					{
						int effx = (x - xpos) ^ xxor;
						UINT16 data = gfxptr[effx / 4];
						UINT8 pen = (data >> 4*(~effx & 3)) & 0x0f;
						if (pen)
						{
							dest[x] = pal_base + pen;
							pdest[x] |= 4;
						}
					}
				}
			}
		}
	}
}

static TILE_GET_INFO( get_fg_tile_info )
{
	const UINT16 *source = twin16_videoram2;
	int attr = source[tile_index];
	int code = attr & 0x1ff;
	int color = (attr >> 9) & 0x0f;

	SET_TILE_INFO(0, code, color, 0);
}

VIDEO_START( twin16 )
{
	fg_tilemap = tilemap_create(machine, get_fg_tile_info, tilemap_scan_rows_flip_y, 8, 8, 64, 32);

	tilemap_set_transparent_pen(fg_tilemap, 0);
}

VIDEO_START( fround )
{
	fg_tilemap = tilemap_create(machine, get_fg_tile_info, tilemap_scan_rows, 8, 8, 64, 32);

	tilemap_set_transparent_pen(fg_tilemap, 0);
}

VIDEO_UPDATE( twin16 )
{
	bitmap_fill(priority_bitmap,cliprect,0);
	draw_layer( bitmap,1 );

	if (twin16_custom_video)
	{
		draw_layer( bitmap,0 );
		draw_sprites( bitmap );
	}
	else	// devilw, vulcan - different priorities order? there should be an enable bit somewhere...
	{
		draw_sprites( bitmap );
		draw_layer( bitmap,0 );
	}

	tilemap_draw(bitmap, cliprect, fg_tilemap, 0, 0);
	return 0;
}

VIDEO_EOF( twin16 )
{
	const address_space *space = cputag_get_address_space(machine, "maincpu", ADDRESS_SPACE_PROGRAM);

	if( twin16_spriteram_process_enable() && need_process_spriteram )
		twin16_spriteram_process();

	need_process_spriteram = 1;

	buffer_spriteram16_w(space,0,0,0xffff);
}

