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

                    -= Seta, Sammy, Visco (SSV) System =-

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

    This hardware only generates sprites. But they're of various types,
    including some large "floating tilemap" ones.

    Sprites RAM is 0x40000 bytes long. The first 0x2000 bytes hold a list of
    sprites to display (the list can be made shorter using an end-of-list marker).

    Each entry in the list (8 bytes) is a multi-sprite (e.g it tells the
    hardware to display up to 32 single-sprites).

    The list looks like this:

    Offset:     Bits:                   Value:

        0.h     f--- ---- ---- ----     Shadow
                -edc ---- ---- ----     Each bit enables 2 bitplanes*
                ---- ba-- ---- ----     X Size (1,2,4,8 tiles)
                ---- --98 ---- ----     Y Size (1,2,4,8 tiles)
                ---- ---- 765- ----     Index of a scroll to apply to the single-sprite(s)
                ---- ---- ---4 3210     Number of single-sprites, minus 1

        2.h     f--- ---- ---- ----     List end
                -edc ba98 7654 3210     Offset of the single-sprite(s) data

        4.h     fedc ba-- ---- ----
                ---- --98 7654 3210     X displacement (ignored by tilemap sprites?)

        6.h     fedc ba-- ---- ----
                ---- --98 7654 3210     Y displacement (ignored by tilemap sprites?)


* bit c, which enables/disables the 2 high order bitplanes (256 / 64 color tiles)
  is the only one implemented. Needed by keithlcy (logo), drifto94 (wheels).

    A single-sprite can be:

    1. a rectangle of tiles (only 1 tile code needs to be specified)
    2. a row of tiles of a tilemap in ram. The row is (always?) as wide
       as the screen and 64 pixels tall.

    Rectangle case(1):
    Offset:     Bits:                   Value:

        0.h                             Code (low bits)

        2.h     f--- ---- ---- ----     Flip X
                -e-- ---- ---- ----     Flip Y
                --dc ba-- ---- ----     Code (high bits)
                ---- --9- ---- ----     Code? Color?
                ---- ---8 7654 3210     Color code (64 color steps)

        4.h     f--- ---- ---- ----     Shadow
                -edc ---- ---- ----     Each bit enables 2 bitplanes*
                ---- ba-- ---- ----     X Size (1,2,4,8 tiles)
                ---- --98 7654 3210     X

        6.h     fedc ---- ---- ----
                ---- ba-- ---- ----     Y Size (1,2,4 tiles) **
                ---- --98 7654 3210     Y


    Tilemap case(2):
    Offset:     Bits:                   Value:

        0.h     fedc ba98 7654 3---
                ---- ---- ---- -210     Scroll index (see below)

        2.h                             Always 0

        4.h     fedc ba-- ---- ----
                ---- --98 7654 3210     X?

        6.h     fedc ---- ---- ----
                ---- ba-- ---- ----     **
                ---- --98 7654 3210     Y

** ? both bits set means "Row Sprite" if the single-sprite type hasn't been
     specified in the sprites list ?

    There are 8 scroll values for the tilemap sprites, in the
    1c0000-1c003f area (each scroll value uses 8 bytes):

    Offset:     Bits:                   Value:

        0.h                             Scroll X

        2.h                             Scroll Y

        4.h                             Priority ? (0000, 0401, 0440, 057f, 05ff)

        6.h     fed- ---- ---- ----     Tilemap width (games only use 1 -> $200, 2 -> $400)
                ---c ---- ---- ----     ?
                ---- b--- ---- ----     Shadow
                ---- -a98 ---- ----     Each bit enables 2 bitplanes*
                ---- ---- 7654 3210     ? some games leave it to 0, others
                                          use e.g 28 for scroll 0, 29 for
                                          scroll 1, 2a etc.

    Where scroll x&y refer to a virtual $8000 x $200 tilemap (filling the
    whole spriteram) made of 16x16 tiles. A tile uses 4 bytes:

    Offset:     Bits:                   Value:

        0.h                             Code (low bits)***

        2.h     f--- ---- ---- ----     Flip X
                -e-- ---- ---- ----     Flip Y
                --dc ba-- ---- ----     Code (high bits)
                ---- --9- ---- ----     Code? Color?
                ---- ---8 7654 3210     Color code (64 color steps)

    The tilemap is stored in ram by column.

*** The tiles size is (always?) 16x16 so Code and Code+1 are used.


    Note that there is a "background layer": a series of tilemap sprites
    that fill up the screen and use scroll 0 as the source tilemap are
    always displayed before the sprites in the sprites list.

    Shadows:

    The low bits of the pens from a "shadowing" tile (regardless of color code)
    substitute the top bits of the color index (0-7fff) in the frame buffer.
    The number of low bits from the "shadowing tile" is 4 or 2, depending on
    bit 7 of 1c0076.

Note: press Z to show some info on each sprite (debug builds only)

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

#include "emu.h"
#include "includes/ssv.h"
#ifdef MAME_DEBUG
#include "ui.h"
#endif


static void ssv_drawgfx(	bitmap_ind16 &bitmap, const rectangle &cliprect, const gfx_element *gfx,
					UINT32 code,UINT32 color,int flipx,int flipy,int x0,int y0,
					int shadow )
{
	ssv_state *state = gfx->machine().driver_data<ssv_state>();
	const UINT8 *addr, *source;
	UINT8 pen;
	UINT16 *dest;
	int sx, x1, dx;
	int sy, y1, dy;

	addr	=	gfx_element_get_data(gfx, code  % gfx->total_elements);
	color	=	gfx->color_granularity * (color % gfx->total_colors);

	if ( flipx )	{	x1 = x0-1;				x0 += gfx->width-1;		dx = -1;	}
	else			{	x1 = x0 + gfx->width;							dx =  1;	}

	if ( flipy )	{	y1 = y0-1;				y0 += gfx->height-1;	dy = -1;	}
	else			{	y1 = y0 + gfx->height;							dy =  1;	}

#define SSV_DRAWGFX(SETPIXELCOLOR)												\
	for ( sy = y0; sy != y1; sy += dy )											\
	{																			\
		if ( sy >= cliprect.min_y && sy <= cliprect.max_y )					\
		{																		\
			source	=	addr;													\
			dest	=	&bitmap.pix16(sy);							\
																				\
			for ( sx = x0; sx != x1; sx += dx )									\
			{																	\
				pen = *source++;												\
																				\
				if ( pen && sx >= cliprect.min_x && sx <= cliprect.max_x )	\
					SETPIXELCOLOR												\
			}																	\
		}																		\
																				\
		addr	+=	gfx->line_modulo;											\
	}

	if (shadow)
	{
		SSV_DRAWGFX( { dest[sx] = ((dest[sx] & state->m_shadow_pen_mask) | (pen << state->m_shadow_pen_shift)) & 0x7fff; } )
	}
	else
	{
		SSV_DRAWGFX( { dest[sx] = (color + pen) & 0x7fff; } )
	}
}


VIDEO_START( ssv )
{
	machine.gfx[0]->color_granularity = 64; /* 256 colour sprites with palette selectable on 64 colour boundaries */
}

VIDEO_START( eaglshot )
{
	ssv_state *state = machine.driver_data<ssv_state>();
	VIDEO_START_CALL(ssv);

	state->m_eaglshot_gfxram		=	auto_alloc_array(machine, UINT16, 16 * 0x40000 / 2);

	gfx_element_set_source(machine.gfx[0], (UINT8 *)state->m_eaglshot_gfxram);
	gfx_element_set_source(machine.gfx[1], (UINT8 *)state->m_eaglshot_gfxram);
}

static TILE_GET_INFO( get_tile_info_0 )
{
	ssv_state *state = machine.driver_data<ssv_state>();
	UINT16 tile = state->m_gdfs_tmapram[tile_index];

	SET_TILE_INFO(3, tile, 0, TILE_FLIPXY( tile >> 14 ));
}

WRITE16_HANDLER( gdfs_tmapram_w )
{
	ssv_state *state = space->machine().driver_data<ssv_state>();

	COMBINE_DATA(&state->m_gdfs_tmapram[offset]);
	state->m_gdfs_tmap->mark_tile_dirty(offset);
}

VIDEO_START( gdfs )
{
	ssv_state *state = machine.driver_data<ssv_state>();

	VIDEO_START_CALL(ssv);

	state->m_eaglshot_gfxram		=	auto_alloc_array(machine, UINT16, 4 * 0x100000 / 2);

	machine.gfx[2]->color_granularity = 64; /* 256 colour sprites with palette selectable on 64 colour boundaries */
	gfx_element_set_source(machine.gfx[2], (UINT8 *)state->m_eaglshot_gfxram);

	state->m_gdfs_tmap			=	tilemap_create(	machine, get_tile_info_0, tilemap_scan_rows,
											 16,16, 0x100,0x100	);

	state->m_gdfs_tmap->set_transparent_pen(0);
}

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

    CRT controller, registers that are read
    (vblank etc.?)

            1c0000 (wait for bit .. to become ..)

    keithlcy:   bit D, 0 -> 1

    mslider:    bit A, 0

    hypreact:
    meosism:
    srmp7:
    sxyreact:
    ultrax: bit F, 0

    twineag2:
    hypreac2:   bit C, 1 -> 0
            bit F, 0

    janjans1:
    srmp4:
    survarts:   no checks

    ryorioh:
    drifto94:   bit D, 0 -> 1
            bit A, 0


    CRT controller, registers that are written
    (resolution, visible area, flipping etc.)

    1c0060-61   ---- ---- ---- ---- ?                           21 or 2b    for all games
    1c0062-63   fedc ba98 7654 3210 x start visible area
    1c0064-65   fedc ba98 7654 3210 x end visible area
    1c0066-67   ---- ---- ---- ---- ?                           1c6     for all games
    1c0068-69   ---- ---- ---- ---- ?                           1       for all games
    1c006a-6b   fedc ba98 7654 3210 y start visible area
    1c006c-6d   fedc ba98 7654 3210 y end visible area
    1c006e-6f   ---- ---- ---- ---- ?                           106     for all games
    1c0070-71   fedc ba98 7654 3210 signed y global tilemap x offset
    1c0072-73   ---- ---- ---- ---- ?
    1c0074-75   ---- ---- ---- ---- ?
                -e-- ---- ---- ---- y flipscreen
                ---c ---- ---- ---- x flipscreen
                ---- ba98 ---- ---- ?                           0101 for all games
                ---- ---- 7654 3210 signed global tilemap x offset
    1c0076-77   -e-- ---- ---- ---- global/local sprites coordinates
                ---- ---- 7--- ---- shadow (0 = 2 bits, 1 = 4 bits)
    1c0078-79   ---- ---- ---- ---- ?
    1c007a-7b   ---- ---- ---- ---- ?
                ---- b--- ---- ---- sprite coordinate mode

            1c0060-7f:

    drifto94:   0000 0025 00cd 01c6 - 0001 0013 0101 0106
            0300 0711 0500 0000 - 0015 5940
            03ea      5558  (flip)

    dynagear:   002b 002c 00d4 01c6 - 0001 0012 0102 0106
            02fd 0000 0500 0000 - 0015 5940
            03ed      5558  (flip)

    eaglshot:   0021 002a 00ca 01c6 - 0001 0016 00f6 0106
            0301 0000 0500 d000 - 0015 5940
            03f1      5560 d00f  (flip)

    gdfs:       002b 002c 00d5 01c6 - 0001 0012 0102 0106
            03ec 0711 0500 0000 - 00d5 5950
            03ec      1557  (flip)

    hypreact:   0021 0022 00cb 01c6 - 0001 000e 00fe 0106
            0301 0000 0500 c000 - 0015 5140
            03f0      5558  (flip)

    hypreac2:   0021 0022 00cb 01c6 - 0001 000e 00fe 0106
            0301 0000 05ff c000 - 0015 5140
            03ea      5558  (flip)

    janjans1:   0021 0023 00cb 01c6 - 0001 000f 00fe 0106
            0300 0000 0500 c000 - 0015 5140
            0300      0500  (flip)

    keithlcy:   002b 0025 00cd 01c6 - 0001 0013 0101 0106
            0300 0711 0500 0000 - 0015 5940
            03ea      5558  (flip)

    meosism:    002b 002c 00d5 01c6 - 0001 0012 00fe 0106
            0301 0000 0500 c000 - 0015 5140
            (no flip)

    mslider:    0021 0026 00d6 01c6 - 0001 000e 00fe 0106
            03f1 0711 5550 c080 - 0015 5940
            0301      0500  (flip)

    ryorioh:    0021 0023*00cb 01c6 - 0001 000f 00fe 0106
            0300 0000 0500 c000 - 0015 5140
            03ed      5558  (flip) *0025

    srmp4:  002b 002c 00d4 01c6 - 0001 0012 0102 0106
            0301 0711 0500 0000 - 0015 4940
            ffe8      5557  (flip)

    srmp7:  002b 002c 00d4 01c6 - 0001 000e 00fd 0106
            0000 0000 e500 0000 - 0015 7140
            02f2      b558  (flip)

    stmblade:   0021 0026 00d6 01c6 - 0001 000e 00fe 0106
            03f1 0711 5550 c080 - 0015 5940         <- 711 becomes 0 during gameplay
            0301      0500  (flip)

    survarts:   002b 002c 00d4 01c6 - 0001 0012 0102 0106
            0301 0000 0500 0000 - 0015 5140
            03e9      5558  (flip)

    sxyreact:   0021 0022 00cb 01c6 - 0001 000e 00fe 0106
            0301 0000 0500 c000 - 0015 5140
            03ef      5558  (flip)

    sxyreac2:   0021 0023 00cb 01c6 - 0001 000e 00fe 0106
            0301 0000 0500 c000 - 0015 5140
            ????      ????  (flip)

    twineag2:   002b 002c 00d4 01c6 - 0001 0012 0102 0106
            ffec 0000 e500 4000 - 0315 7940
            ????      ????  (flip)

    ultrax: 002b 002c 00d4 01c6 - 0001 0012 0102 0106
            ffec 0000 e500 4000 - 0315 7940
            02fe      b558  (flip)

    vasara &    0021 0024 00cc 01c6 - 0001 000e 00fe 0106
    vasara2:    03f1 0000 6500 c000 - 0015 5140
            0301      3558  (flip)


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

READ16_HANDLER( ssv_vblank_r )
{
	if (space->machine().primary_screen->vblank())
		return 0x2000 | 0x1000;
	else
		return 0x0000;
}

WRITE16_HANDLER( ssv_scroll_w )
{
	ssv_state *state = space->machine().driver_data<ssv_state>();

	COMBINE_DATA(state->m_scroll + offset);

/*  offsets 60-7f: CRT Controller   */

}

WRITE16_HANDLER( paletteram16_xrgb_swap_word_w )
{
	ssv_state *state = space->machine().driver_data<ssv_state>();
	int r, g, b;
	UINT16 data0, data1;

	COMBINE_DATA(state->m_paletteram + offset);

	offset &= ~1;

	data0 = state->m_paletteram[offset + 1];
	data1 = state->m_paletteram[offset];

	r = data0 & 0xff;
	g = data1 >> 8;
	b = data1 & 0xff;

	palette_set_color(space->machine(), offset>>1, MAKE_RGB(r, g, b));
}

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


                                Sprites Drawing

[mslider]
"Insert coins"          101f60: 0006 0825 00b0 000c
                        104128: 1a3a 0000 63d4 0400 (16x16)

Character tilemap       100080: 000f 0410 0000 0000
                        102080: 0002 0000 6200 0c00
                                0002 0000 6200 0c40
                                0002 0000 6200 0c80
                                0002 0000 6200 0cc0
                                0002 0000 6200 0d00
                                ..
                                0002 0000 6200 0fc0
                        1c0010: 73f0 00f1 05ff 4600


[hypreact]
intro                   100140: 6003 04ca 0000 0000 (tilemap sprite)
                        102650: 0003 0000 0000 0c00
                                0003 0000 0000 0c40
                                0003 0000 0000 0c80
                                0003 0000 0000 0cc0
                        1c0018: 15f8 00e8 057f 2600

game                    100058: 6003 00db 0050 0040 (normal sprite)
                        1006d8: 037c 001b 6400 0400

tiles                   100060: 6019 0120 0014 000a (sometimes 6619!)
                        100900: 0a8c 0012 6400 0420 (32x16)
                                0400 0012 6400 0800 (32x32)
                                ...

[hypreac2]
"warning"               100f60: 6106 3893 0068 00c8 (128x32)
                        11c498: 00e0 00b2 6c00 0800
                                0000 0000 0000 0000
text below "warning"    100f70: 6016 389b 0048 00b0 ((16 or 8)x8)
                        11c4d8: 0054 0007 6000 0000

black regions           100af8: 6303 2d64 0000 03f8 (yoffs should be used)
                        116b20: 0004 0000 0000 0fa0 <- move up and down
                                0004 0000 0000 0fe0
                                0004 0000 0000 0ce0
                                0004 0000 0000 0d20
                        1c0020: 6c00 00ef 057f 2600

"credits"               1012f0: 6007 440e 00e0 0008 (16x8)
                        122070: 0043 0006 6000 0000

tiles                   100ce8: 6111 3464 0008 0030 (16x32,empty tile frames)
                        11a320: 0460 006b 6110 0800
                                0460 006b 6100 0800
                                ..
                        100d68: 6205 34de 0008 0030 (16x32, tiles on frames)
                        11a6f0: 050c 0059 6000 0800
                                04c0 005a 6010 0800
                                04d4 005a 6020 0800
                                0500 0059 6030 0800
                                ..
                        100cf8: 6105 348a 0008 fff8 (16x16 x 2x3, big tiles below)
                        11a450: 61d6 0059 6000 0420
                                61f2 0059 6000 0410
                                6212 0059 6000 0400
                                61d8 0059 6010 0420
                                61f4 0059 6010 0410
                                6214 0059 6010 0400

[keithlcy]
high scores             101030: 717f 40c0 0010 0000
                        120600: 0000 0000 00c0 0025 (16x16)
                                0000 0000 00d0 0025
                                ..
                                0000 0000 0000 ffff (ysize should be 16!)
                                0000 0000 0010 ffff
                                ..

K of "KEITH"            101180: 610e 4600 0020 0090
                        123000: 4ef4 016a 0000 0040 (16x16)
                                4ef6 016a 0010 0040
                                ..

floating robot (demo)   101000: 713d 4000 03b0 0088
                        120000: ..
                                71f6 0020 0000 0030
                                71f8 0020 0010 0030
                                ..

cityscape               100030: 7304 1600 0000 007c (yoffs should not be used)
                        10b000: 0001 0000 0200 0000
                                0001 0000 0200 0040
                                0001 0000 0200 0080
                                0001 0000 0200 00c0
                        1c0008: 0800 00f2 05ff 5729


[meosism]
shadows                 100100: 701f 051b 0041 0020 (16x16 shadow)
                        1028d8: 05aa 0030 f000 0470

[srmp4]
logo                    100000: 6303 1680 0180 0078 (yoffs?)
                        10b400: 0001 0000 0000 0060
                                0001 0000 0000 0020
                                0001 0000 0000 ffe0
                                0001 0000 0000 ffa0
                        1c0008: 0800 00ec 05ff 5629

tiles                   100088: 6103 25b7 0028 000a (16x16)
                        112db8: f4aa 0009 03f8 0018
                                f4a8 0009 0008 0018
                                f4ba 0009 03f8 0008
                                f4bc 0009 0008 0008

[survarts]
tilemap                 100030: 6303 2048 0000 0000
                        110240: 0002 0000 0160 03fc
                                0002 0000 0160 003c
                                0002 0000 0160 007c
                                0002 0000 0160 00bc
                        1c0010: 0c2e 01f5 05ff 4628

player                  100030: 611f 1da0 0000 fffc
                        10ed00: eb16 200f 005c fffa (16x16)

"push start"            100130: 601d 1920 0048 0000
                        10c900: 0441 0004 0000 004c (16x8)

[drifto94]
car shadow              100010: 8137 0640 0080 0030
                        103200: ..
                                544a 21e4 0030 0030 (16x16)

writings on finish      100130: 6109 4840 004e 0058 "good work"
                        124200: ee6e 0135 0024 0000 (16x16)
                        100158: 611e 4860 0058 0020 "you have proved yOur"..
                        124300: ee92 0137 0024 0014 (16x16)
                                ..
                                ee7e 0137 fff4 0000 (16x16!!)   ; 'O'
                                ..

[ultrax]
sprite begin of lev1    100010: 6b60 4280 0016 00a0
                        121400: 51a0 0042 6800 0c00 (64x64)

[eaglshot]
title logo              100040: 001b 2920 0048 00e0
                        114900: 2130 0060 7018 0fd0 (16x64)

play                    100020: 0003 290c 0000 0000
                        114860: 0003 0000 03f0 0ce0 (tilemap)

sammy logo              100020: 0003 1000 0000 0000
                        108000: 0001 0000 4380 0ce0 (tilemap)

From the above some noteworthy cases are:

            101f60: 0006 0825 00b0 000c
            104128: 1a3a 0000 63d4 0400     consider y size

            101030: 717f 40c0 0010 0000
            120600: 0000 0000 0000 ffff     ignore y size & depth

            100158: 611e 4860 0058 0020
            124300  ee7e 0137 fff4 0000     ignore x size & depth

            100f60: 6106 3893 0068 00c8
            11c498: 00e0 00b2 6c00 0800     consider x size & y size

            100100: 701f 051b 0041 0020
            1028d8: 05aa 0030 f000 0470     consider shadow (16x16 shadow)

            100010: 6b60 4280 0016 00a0
            121400: 51a0 0042 6800 0c00     (64x64)

            100140: 6003 04ca 0000 0000     tilemap
            102650: 0003 0000 0000 0c00

            100080: 000f 0410 0000 0000     tilemap
            102080: 0002 0000 6200 0c00

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

/* Draw a tilemap sprite */

static void draw_row(running_machine &machine, bitmap_ind16 &bitmap, const rectangle &cliprect, int sx, int sy, int scroll)
{
	ssv_state *state = machine.driver_data<ssv_state>();
	UINT16 *spriteram16 = state->m_spriteram;
	UINT16 *ssv_scroll = state->m_scroll;
	rectangle clip;
	int attr, code, color, mode, size, page, shadow;
	int x, x1, sx1, flipx, xnum, xstart, xend, xinc;
	int y, y1, sy1, flipy, ynum, ystart, yend, yinc;
	UINT16 *s3;

	xnum = 0x20;		// width in tiles (screen-wide)
	ynum = 0x8;			// height in tiles (always 64 pixels?)

	scroll &= 0x7;		// scroll register index

	/* Sign extend the position */
	sx = 0;
	sy = (sy & 0x1ff) - (sy & 0x200);

	/* Set up a clipping region for the tilemap slice .. */

	clip.set(sx, sx + xnum * 0x10 - 1, sy, sy + ynum * 0x8  - 1);

	/* .. and clip it against the visible screen */

	if (clip.min_x > cliprect.max_x)	return;
	if (clip.min_y > cliprect.max_y)	return;

	if (clip.max_x < cliprect.min_x)	return;
	if (clip.max_y < cliprect.min_y)	return;

	if (clip.min_x < cliprect.min_x)	clip.min_x = cliprect.min_x;
	if (clip.max_x > cliprect.max_x)	clip.max_x = cliprect.max_x;

	if (clip.min_y < cliprect.min_y)	clip.min_y = cliprect.min_y;
	if (clip.max_y > cliprect.max_y)	clip.max_y = cliprect.max_y;

	/* Get the scroll data */
	x    = ssv_scroll[ scroll * 4 + 0 ];	// x scroll
	y    = ssv_scroll[ scroll * 4 + 1 ];	// y scroll
	//     ssv_scroll[ scroll * 4 + 2 ];    // ???
	mode = ssv_scroll[ scroll * 4 + 3 ];	// layer disabled, shadow, depth etc.

	/* Background layer disabled */
	if ((mode & 0xe000) == 0)
		return;

	shadow = (mode & 0x0800);

	/* Decide the actual size of the tilemap */
	size	=	1 << (8 + ((mode & 0xe000) >> 13));
	page	=	(x & 0x7fff) / size;

	/* Given a fixed scroll value, the portion of tilemap displayed changes with the sprite position */
	x += sx;
	y += sy;

	/* Tweak the scroll values */
	// x += 0;
	y    += ((ssv_scroll[0x70/2] & 0x1ff) - (ssv_scroll[0x70/2] & 0x200) + ssv_scroll[0x6a/2] + 2);

	// Kludge for eaglshot
	if ((ssv_scroll[ scroll * 4 + 2 ] & 0x05ff) == 0x0440) x += -0x10;
	if ((ssv_scroll[ scroll * 4 + 2 ] & 0x05ff) == 0x0401) x += -0x20;

	/* Draw the rows */
	x1  = x;
	y1  = y;
	sx1 = sx - (x & 0xf);
	sy1 = sy - (y & 0xf);

	for (sx=sx1,x=x1; sx <= clip.max_x; sx+=0x10,x+=0x10)
	{
		for (sy=sy1,y=y1; sy <= clip.max_y; sy+=0x10,y+=0x10)
		{
			int tx, ty, gfx;

			s3	=	&spriteram16[	page * (size * ((0x1000/0x200)/2))	+
									((x & ((size -1) & ~0xf)) << 2)	+
									((y & ((0x200-1) & ~0xf)) >> 3)		];

			code	=	s3[0];	// code high bits
			attr	=	s3[1];	// code low  bits + color

			/* Code's high bits are scrambled */
			code	+=	state->m_tile_code[(attr & 0x3c00)>>10];
			flipy	=	(attr & 0x4000);
			flipx	=	(attr & 0x8000);

			if ((ssv_scroll[0x74/2] & 0x1000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
			{
				if (flipx == 0) flipx = 1; else flipx = 0;
			}
			if ((ssv_scroll[0x74/2] & 0x4000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
			{
				if (flipy == 0) flipy = 1; else flipy = 0;
			}

			color	=	attr;

			/* Select 256 or 64 color tiles */
			gfx	=	((mode & 0x0100) ? 0 : 1);

			/* Force 16x16 tiles ? */
			if (flipx)	{ xstart = 1-1;  xend = -1; xinc = -1; }
			else		{ xstart = 0;    xend = 1;  xinc = +1; }

			if (flipy)	{ ystart = 2-1;  yend = -1; yinc = -1; }
			else		{ ystart = 0;    yend = 2;  yinc = +1; }

			/* Draw a tile (16x16) */
			for (tx = xstart; tx != xend; tx += xinc)
			{
				for (ty = ystart; ty != yend; ty += yinc)
				{
					ssv_drawgfx( bitmap, clip, machine.gfx[gfx],
											code++,
											color,
											flipx, flipy,
											sx + tx * 16, sy + ty * 8,
											shadow	);
				} /* ty */
			} /* tx */

		} /* sy */
	} /* sx */

}

/* Draw the "background layer" using multiple tilemap sprites */

static void draw_layer(running_machine &machine, bitmap_ind16 &bitmap, const rectangle &cliprect, int  nr)
{
	int sy;
	for ( sy = 0; sy <= machine.primary_screen->visible_area().max_y; sy += 0x40 )
		draw_row(machine, bitmap, cliprect, 0, sy, nr);
}

/* Draw sprites in the sprites list */

static void draw_sprites(running_machine &machine, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	/* Sprites list */
	ssv_state *state = machine.driver_data<ssv_state>();
	UINT16 *ssv_scroll = state->m_scroll;
	UINT16 *spriteram16 = state->m_spriteram;

	UINT16 *s1	=	spriteram16;
	UINT16 *end1	=	spriteram16 + 0x02000/2;
	UINT16 *end2	=	spriteram16 + 0x40000/2;
	UINT16 *s2;

	for ( ; s1 < end1; s1+=4 )
	{
		int attr, code, color, num, sprite;
		int sx, x, xoffs, flipx, xnum, xstart, xend, xinc, sprites_offsx;
		int sy, y, yoffs, flipy, ynum, ystart, yend, yinc, sprites_offsy, tilemaps_offsy;
		int mode,global_depth,global_xnum,global_ynum;

		mode   = s1[ 0 ];
		sprite = s1[ 1 ];
		xoffs  = s1[ 2 ];
		yoffs  = s1[ 3 ];

		/* Last sprite */
		if (sprite & 0x8000) break;

		/* Single-sprite address */
		s2 = &spriteram16[ (sprite & 0x7fff) * 4 ];
		tilemaps_offsy = ((s2[3] & 0x1ff) - (s2[3] & 0x200));

		/* Every single sprite is offset by x & yoffs, and additionally
        by one of the 8 x & y offsets in the 1c0040-1c005f area   */

		xoffs	+=		ssv_scroll[((mode & 0x00e0) >> 4) + 0x40/2];
		yoffs	+=		ssv_scroll[((mode & 0x00e0) >> 4) + 0x42/2];

		/* Number of single-sprites (1-32) */
		num				=	(mode & 0x001f) + 1;
		global_ynum		=	(mode & 0x0300) << 2;
		global_xnum		=	(mode & 0x0c00);
		global_depth	=	(mode & 0xf000);

		for( ; num > 0; num--,s2+=4 )
		{
			int depth, local_depth, local_xnum, local_ynum;

			if (s2 >= end2)	break;

			sx		=		s2[ 2 ];
			sy		=		s2[ 3 ];

			local_depth		=	sx & 0xf000;
			local_xnum		=	sx & 0x0c00;
			local_ynum		=	sy & 0x0c00;

			if (ssv_scroll[0x76/2] & 0x4000)
			{
				xnum	=	local_xnum;
				ynum	=	local_ynum;
				depth	=	local_depth;
			}
			else
			{
				xnum	=	global_xnum;
				ynum	=	global_ynum;
				depth	=	global_depth;
			}

			if ( s2[0] <= 7 && s2[1] == 0 && xnum == 0 && ynum == 0x0c00)
			{
				// Tilemap Sprite
				int scroll;

				scroll	=	s2[ 0 ];	// scroll index

				if (ssv_scroll[0x76/2] & 0x1000)
					sy -= 0x20;						// eaglshot
				else
				{
					if (ssv_scroll[0x7a/2] & 0x0800)
					{
						if (ssv_scroll[0x7a/2] & 0x1000)	// drifto94, dynagear, keithlcy, mslider, stmblade, gdfs, ultrax, twineag2
							sy -= tilemaps_offsy;
						else						// srmp4
							sy += tilemaps_offsy;
					}
				}

				if ((mode & 0x001f) != 0)
					draw_row(machine, bitmap, cliprect, sx, sy, scroll);
			}
			else
			{
				// "Normal" Sprite
/*
    hot spots:
    "warning" in hypreac2 has mode & 0x0100 and is not 16x16
    keithlcy high scores has mode & 0x0100 and y & 0x0c00 can be 0x0c00
    drifto94 "you have proved yOur".. has mode & 0x0100 and x & 0x0c00 can be 0x0c00
    ultrax (begin of lev1): 100010: 6b60 4280 0016 00a0
                            121400: 51a0 0042 6800 0c00 needs to be a normal sprite
*/

				int shadow, gfx;
				if (s2 >= end2)	break;

				code	=	s2[0];	// code high bits
				attr	=	s2[1];	// code low  bits + color

				/* Code's high bits are scrambled */
				code	+=	state->m_tile_code[(attr & 0x3c00)>>10];
				flipy	=	(attr & 0x4000);
				flipx	=	(attr & 0x8000);

				if ((ssv_scroll[0x74/2] & 0x1000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
				{
					if (flipx == 0) flipx = 1; else flipx = 0;
				}
				if ((ssv_scroll[0x74/2] & 0x4000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
				{
					if (flipy == 0) flipy = 1; else flipy = 0;
				}

				color	=	attr;

				/* Select 256 or 64 color tiles */
				gfx		=	(depth & 0x1000) ? 0 : 1;
				shadow	=	(depth & 0x8000);

				/* Single-sprite tile size */
				xnum = 1 << (xnum >> 10);	// 1, 2, 4 or 8 tiles
				ynum = 1 << (ynum >> 10);	// 1, 2, 4 tiles (8 means tilemap sprite?)

				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; }

				/* Apply global offsets */
				sx	+=	xoffs;
				sy	+=	yoffs;

				/* Sign extend the position */
				sx	=	(sx & 0x1ff) - (sx & 0x200);
				sy	=	(sy & 0x1ff) - (sy & 0x200);

				sprites_offsx =  ((ssv_scroll[0x74/2] & 0x7f) - (ssv_scroll[0x74/2] & 0x80));

				sprites_offsy = -((ssv_scroll[0x70/2] & 0x1ff) - (ssv_scroll[0x70/2] & 0x200) + ssv_scroll[0x6a/2] + 1);

				if (ssv_scroll[0x74/2] & 0x4000) // flipscreen y
				{
					sy = -sy;
					if (ssv_scroll[0x74/2] & 0x8000)
						sy += 0x00;			//
					else
						sy -= 0x10;			// vasara (hack)
				}

				if (ssv_scroll[0x74/2] & 0x1000) // flipscreen x
				{
					sx = -sx + 0x100;
				}

				// sprites can be relative to a side, the other side or the center

				if (ssv_scroll[0x7a/2] == 0x7140)
				{
					// srmp7
					sx	=	sprites_offsx + sx;
					sy	=	sprites_offsy - sy;
				}
				else if (ssv_scroll[0x7a/2] & 0x0800)
				{
					// dynagear, drifto94, eaglshot, keithlcy, mslider, srmp4, stmblade, twineag2, ultrax
					sx	=	sprites_offsx + sx - (xnum * 8)    ;
					sy	=	sprites_offsy - sy - (ynum * 8) / 2;
				}
				else
				{
					// hypreact, hypreac2, janjans1, meosism, ryorioh, survarts, sxyreact, sxyreac2, vasara, vasara2
					sx	=	sprites_offsx + sx;
					sy	=	sprites_offsy - sy - (ynum * 8);
				}



				/* Sprite code masking */
				if (xnum == 2 && ynum == 4) // needed by hypreact
				{
					code &= ~7;
				}

				/* Draw the tiles */

				for (x = xstart; x != xend; x += xinc)
				{
					for (y = ystart; y != yend; y += yinc)
					{
						ssv_drawgfx( bitmap, cliprect, machine.gfx[gfx],
												code++,
												color,
												flipx, flipy,
												sx + x * 16, sy + y * 8,
												shadow );
					}
				}

				#ifdef MAME_DEBUG
				if (machine.input().code_pressed(KEYCODE_Z))	/* Display some info on each sprite */
				{	char buf[30];
					sprintf(buf, "%02X",/*(s2[2] & ~0x3ff)>>8*/mode>>8);
					ui_draw_text(&machine.render().ui_container(), buf, sx, sy);
				}
				#endif

			}		/* sprite type */

		}	/* single-sprites */

	}	/* sprites list */
}


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


                                Screen Drawing


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

SCREEN_UPDATE_IND16( eaglshot )
{
	return SCREEN_UPDATE16_CALL(ssv);
}

/*
    Sprites RAM is 0x80000 bytes long. The first 0x2000? bytes hold a list
    of sprites to display (the list can be made shorter using an end-of-list
    marker).

    Each entry in the list (16 bytes) is a multi-sprite (e.g it tells the
    hardware to display several single-sprites).

    The list looks like this:

    Offset:     Bits:                   Value:

        0.h     fedc ba-- ---- ----
                ---- --98 7654 3210     X displacement

        2.h     fedc ba-- ---- ----
                ---- --98 7654 3210     Y displacement

        4.h     f--- ---- ---- ----     List end
                -edc ba98 7654 3210     Offset of the single-sprite(s) data

        0.h                             Number of single-sprites (how many bits?)

    A single-sprite is:

    Offset:     Bits:                   Value:

        0.h                             Code

        2.h     f--- ---- ---- ----     Flip X
                -e-- ---- ---- ----     Flip Y
                ---- -a-- ---- ----     0 = 256 color steps, 1 = 64 color steps
                ---- --98 7654 3210     Color code

        4.h     fedc ba-- ---- ----
                ---- --98 7654 3210     X displacement

        6.h     fedc ba-- ---- ----
                ---- --98 7654 3210     Y displacement

        8.h     fedc ba98 ---- ----     Y Size
                ---- ---- 7654 3210     X Size

        A.h     fedc ba98 ---- ----
                ---- ---- 7654 ----     Priority
                ---- ---- ---- 32--     Y Tiles (1,2,4,8)
                ---- ---- ---- --10     X Tiles (1,2,4,8)

        C.h                             Unused

        E.h                             Unused

*/
static void gdfs_draw_zooming_sprites(running_machine &machine, bitmap_ind16 &bitmap, const rectangle &cliprect, int priority)
{
	/* Sprites list */

	ssv_state *state = machine.driver_data<ssv_state>();
	UINT16 *spriteram16_2 = state->m_spriteram2;
	UINT16 *s1	=	spriteram16_2;
	UINT16 *end1	=	spriteram16_2 + 0x02000/2;
	UINT16 *s2;

	priority <<= 4;

	for ( ; s1 < end1; s1+=8/2 )
	{
		int attr, code, color, num, sprite, zoom, size;
		int sx, x, xoffs, flipx, xnum, xstart, xend, xinc, xdim, xscale;
		int sy, y, yoffs, flipy, ynum, ystart, yend, yinc, ydim, yscale;

		xoffs	=		s1[ 0 ];
		yoffs	=		s1[ 1 ];
		sprite	=		s1[ 2 ];
		num		=		s1[ 3 ] % 0x101;

		/* Last sprite */
		if (sprite & 0x8000) break;

		/* Single-sprite address */
		s2		=		&spriteram16_2[ (sprite & 0x7fff) * 16/2 ];

		for( ; num > 0; num--,s2+=16/2 )
		{
			code	=	s2[ 0 ];
			attr	=	s2[ 1 ];
			sx		=	s2[ 2 ];
			sy		=	s2[ 3 ];
			zoom	=	s2[ 4 ];
			size	=	s2[ 5 ];

			if (priority != (size & 0xf0))
				break;

			flipx	=	(attr & 0x8000);
			flipy	=	(attr & 0x4000);

/*
            if ((ssv_scroll[0x74/2] & 0x1000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
            {
                if (flipx == 0) flipx = 1; else flipx = 0;
            }
            if ((ssv_scroll[0x74/2] & 0x4000) && ((ssv_scroll[0x74/2] & 0x2000) == 0))
            {
                if (flipy == 0) flipy = 1; else flipy = 0;
            }
*/

			color	=	(attr & 0x0400) ? attr : attr * 4;

			/* Single-sprite tile size */
			xnum = 1 << ((size >> 0) & 3);
			ynum = 1 << ((size >> 2) & 3);

			xnum = (xnum + 1) / 2;

			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; }

			/* Apply global offsets */
			sx	+=	xoffs;
			sy	+=	yoffs;

			/* Sign extend the position */
			sx	=	(sx & 0x1ff) - (sx & 0x200);
			sy	=	(sy & 0x1ff) - (sy & 0x200);

			sy	=	-sy;

			/* Use fixed point values (16.16), for accuracy */
			sx <<= 16;
			sy <<= 16;

			xdim	=	( ( ((zoom >> 0) & 0xff) + 1) << 16 ) / xnum;
			ydim	=	( ( ((zoom >> 8) & 0xff) + 1) << 16 ) / ynum;

			xscale	=	xdim / 16;
			yscale	=	ydim / 8;

			/* Let's approximate to the nearest greater integer value
               to avoid holes in between tiles */
			if (xscale & 0xffff)	xscale += (1<<16) / 16;
			if (yscale & 0xffff)	yscale += (1<<16) / 8;

			/* Draw the tiles */

			for (x = xstart; x != xend; x += xinc)
			{
				for (y = ystart; y != yend; y += yinc)
				{
					drawgfxzoom_transpen( bitmap, cliprect, machine.gfx[2],
									code++,
									color,
									flipx, flipy,
									(sx + x * xdim) / 0x10000, (sy + y * ydim) / 0x10000,
									xscale, yscale, 0
					);
				}
			}

			#ifdef MAME_DEBUG
			if (machine.input().code_pressed(KEYCODE_Z))	/* Display some info on each sprite */
			{
				char buf[10];
				sprintf(buf, "%X",size);
				ui_draw_text(&machine.render().ui_container(), buf, sx / 0x10000, sy / 0x10000);
			}
			#endif
		}	/* single-sprites */

	}	/* sprites list */
}

SCREEN_UPDATE_IND16( gdfs )
{
	ssv_state *state = screen.machine().driver_data<ssv_state>();
	int pri;

	SCREEN_UPDATE16_CALL(ssv);

	for (pri = 0; pri <= 0xf; pri++)
		gdfs_draw_zooming_sprites(screen.machine(), bitmap, cliprect, pri);

	state->m_gdfs_tmap->set_scrollx(0, state->m_gdfs_tmapscroll[0x0c/2]);
	state->m_gdfs_tmap->set_scrolly(0, state->m_gdfs_tmapscroll[0x10/2]);
	state->m_gdfs_tmap->draw(bitmap, cliprect, 0, 0);

	return 0;
}

void ssv_enable_video(running_machine &machine, int enable)
{
	ssv_state *state = machine.driver_data<ssv_state>();

	state->m_enable_video = enable;
}

SCREEN_UPDATE_IND16( ssv )
{
	rectangle clip;

	ssv_state *state = screen.machine().driver_data<ssv_state>();

	// Shadow
	if (state->m_scroll[0x76/2] & 0x0080)
	{
		// 4 bit shadows (mslider, stmblade)
		state->m_shadow_pen_shift = 15-4;
	}
	else
	{
		// 2 bit shadows
		state->m_shadow_pen_shift = 15-2;
	}
	state->m_shadow_pen_mask = (1 << state->m_shadow_pen_shift) - 1;

	/* The background color is the first one in the palette */
	bitmap.fill(0, cliprect);

	// used by twineag2 and ultrax
	clip.min_x = (cliprect.max_x / 2 + state->m_scroll[0x62/2]) * 2 - state->m_scroll[0x64/2] * 2 + 2;
	clip.max_x = (cliprect.max_x / 2 + state->m_scroll[0x62/2]) * 2 - state->m_scroll[0x62/2] * 2 + 1;
	clip.min_y = (cliprect.max_y     + state->m_scroll[0x6a/2])     - state->m_scroll[0x6c/2]     + 1;
	clip.max_y = (cliprect.max_y     + state->m_scroll[0x6a/2])     - state->m_scroll[0x6a/2]        ;

//  printf("%04x %04x %04x %04x\n",clip.min_x, clip.max_x, clip.min_y, clip.max_y);

	if (clip.min_x < 0) clip.min_x = 0;
	if (clip.min_y < 0) clip.min_y = 0;
	if (clip.max_x > cliprect.max_x) clip.max_x = cliprect.max_x;
	if (clip.max_y > cliprect.max_y) clip.max_y = cliprect.max_y;

	if (clip.min_x > clip.max_x)
		clip.min_x = clip.max_x;
	if (clip.min_y > clip.max_y)
		clip.min_y = clip.max_y;

	if (!state->m_enable_video)
		return 0;

	draw_layer(screen.machine(), bitmap, clip, 0);	// "background layer"

	draw_sprites(screen.machine(), bitmap, clip);	// sprites list


	return 0;
}
