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path: root/src/mame/video/xybots.cpp
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// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************

    Atari Xybots hardware

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

#include "emu.h"
#include "machine/atarigen.h"
#include "video/atarimo.h"
#include "includes/xybots.h"



/*************************************
 *
 *  Tilemap callbacks
 *
 *************************************/

TILE_GET_INFO_MEMBER(xybots_state::get_alpha_tile_info)
{
	uint16_t data = m_alpha_tilemap->basemem_read(tile_index);
	int code = data & 0x3ff;
	int color = (data >> 12) & 7;
	int opaque = data & 0x8000;
	SET_TILE_INFO_MEMBER(2, code, color, opaque ? TILE_FORCE_LAYER0 : 0);
}


TILE_GET_INFO_MEMBER(xybots_state::get_playfield_tile_info)
{
	uint16_t data = m_playfield_tilemap->basemem_read(tile_index);
	int code = data & 0x1fff;
	int color = (data >> 11) & 0x0f;
	SET_TILE_INFO_MEMBER(0, code, color, (data >> 15) & 1);
}



/*************************************
 *
 *  Video system start
 *
 *************************************/

const atari_motion_objects_config xybots_state::s_mob_config =
{
	1,                  /* index to which gfx system */
	1,                  /* number of motion object banks */
	0,                  /* are the entries linked? */
	0,                  /* are the entries split? */
	0,                  /* render in reverse order? */
	0,                  /* render in swapped X/Y order? */
	0,                  /* does the neighbor bit affect the next object? */
	0,                  /* pixels per SLIP entry (0 for no-slip) */
	0,                  /* pixel offset for SLIPs */
	0,                  /* maximum number of links to visit/scanline (0=all) */

	0x100,              /* base palette entry */
	0x300,              /* maximum number of colors */
	0,                  /* transparent pen index */

	{{ 0x3f }},         /* mask for the link (dummy) */
	{{ 0x3fff,0,0,0 }}, /* mask for the code index */
	{{ 0,0,0,0x000f }}, /* mask for the color */
	{{ 0,0,0,0xff80 }}, /* mask for the X position */
	{{ 0,0,0xff80,0 }}, /* mask for the Y position */
	{{ 0 }},            /* mask for the width, in tiles*/
	{{ 0,0,0x0007,0 }}, /* mask for the height, in tiles */
	{{ 0x8000,0,0,0 }}, /* mask for the horizontal flip */
	{{ 0 }},            /* mask for the vertical flip */
	{{ 0,0x000f,0,0 }}, /* mask for the priority */
	{{ 0 }},            /* mask for the neighbor */
	{{ 0 }},            /* mask for absolute coordinates */

	{{ 0 }},            /* mask for the special value */
	0                   /* resulting value to indicate "special" */
};



/*************************************
 *
 *  Main refresh
 *
 *************************************/

uint32_t xybots_state::screen_update_xybots(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	// start drawing
	m_mob->draw_async(cliprect);

	/* draw the playfield */
	m_playfield_tilemap->draw(screen, bitmap, cliprect, 0, 0);

	// draw and merge the MO
	bitmap_ind16 &mobitmap = m_mob->bitmap();
	for (const sparse_dirty_rect *rect = m_mob->first_dirty_rect(cliprect); rect != nullptr; rect = rect->next())
		for (int y = rect->top(); y <= rect->bottom(); y++)
		{
			uint16_t *mo = &mobitmap.pix16(y);
			uint16_t *pf = &bitmap.pix16(y);
			for (int x = rect->left(); x <= rect->right(); x++)
				if (mo[x] != 0xffff)
				{
					/* verified via schematics:

					    PRIEN = ~(~MOPIX3 & ~MOPIX2 & ~MOPIX1) = (MOPIX3-0 > 1)

					    if (PRIEN)
					        PF/MO = (~MOPRI3-0 > PFCOL3-0)
					    else
					        PF/MO = (~MOPRI3-0 >= PFCOL3-0)

					    if (PF/MO | ~(PRIEN & MOCOL3))
					        GPC(P3-0) = PFPIX3-0
					    else
					        GPC(P3-0) = ~MOCOL3-0
					*/
					int mopriority = (mo[x] >> atari_motion_objects_device::PRIORITY_SHIFT) ^ 15;
					int pfcolor = (pf[x] >> 4) & 0x0f;
					int prien = ((mo[x] & 0x0f) > 1);

					if (prien)
					{
						if (mopriority <= pfcolor)
						{
							/* this first case doesn't make sense from the schematics, but it has */
							/* the correct effect */
							if (mo[x] & 0x80)
								pf[x] = (mo[x] ^ 0x2f0) & atari_motion_objects_device::DATA_MASK;
							else
								pf[x] = mo[x] & atari_motion_objects_device::DATA_MASK;
						}
					}
					else
					{
						if (mopriority < pfcolor)
							pf[x] = mo[x] & atari_motion_objects_device::DATA_MASK;
					}
				}
		}

	/* add the alpha on top */
	m_alpha_tilemap->draw(screen, bitmap, cliprect, 0, 0);
	return 0;
}