// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************
Midway MCR-68k system
***************************************************************************/
#include "emu.h"
#include "includes/mcr68.h"
#define LOW_BYTE(x) ((x) & 0xff)
/*************************************
*
* Tilemap callbacks
*
*************************************/
TILE_GET_INFO_MEMBER(mcr68_state::get_bg_tile_info)
{
uint16_t *videoram = m_videoram;
int data = LOW_BYTE(videoram[tile_index * 2]) | (LOW_BYTE(videoram[tile_index * 2 + 1]) << 8);
int code = (data & 0x3ff) | ((data >> 4) & 0xc00);
int color = (~data >> 12) & 3;
SET_TILE_INFO_MEMBER(0, code, color, TILE_FLIPYX(data >> 10));
if (m_gfxdecode->gfx(0)->elements() < 0x1000)
tileinfo.category = (data >> 15) & 1;
}
/*************************************
*
* Video startup
*
*************************************/
VIDEO_START_MEMBER(mcr68_state,mcr68)
{
/* initialize the background tilemap */
m_bg_tilemap = &machine().tilemap().create(*m_gfxdecode, tilemap_get_info_delegate(*this, FUNC(mcr68_state::get_bg_tile_info)), TILEMAP_SCAN_ROWS, 16,16, 32,32);
m_bg_tilemap->set_transparent_pen(0);
}
/*************************************
*
* Video RAM writes
*
*************************************/
WRITE16_MEMBER(mcr68_state::mcr68_videoram_w)
{
uint16_t *videoram = m_videoram;
COMBINE_DATA(&videoram[offset]);
m_bg_tilemap->mark_tile_dirty(offset / 2);
}
/*************************************
*
* Sprite update
*
*************************************/
void mcr68_state::mcr68_update_sprites(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect, int priority)
{
rectangle sprite_clip = m_screen->visible_area();
uint16_t *spriteram = m_spriteram;
int offs;
/* adjust for clipping */
sprite_clip.min_x += m_sprite_clip;
sprite_clip.max_x -= m_sprite_clip;
sprite_clip &= cliprect;
screen.priority().fill(1, sprite_clip);
/* loop over sprite RAM */
for (offs = m_spriteram.bytes() / 2 - 4;offs >= 0;offs -= 4)
{
int code, color, flipx, flipy, x, y, flags;
flags = LOW_BYTE(spriteram[offs + 1]);
code = LOW_BYTE(spriteram[offs + 2]) + 256 * ((flags >> 3) & 0x01) + 512 * ((flags >> 6) & 0x03);
/* skip if zero */
if (code == 0)
continue;
/* also skip if this isn't the priority we're drawing right now */
if (((flags >> 2) & 1) != priority)
continue;
/* extract the bits of information */
color = ~flags & 0x03;
flipx = flags & 0x10;
flipy = flags & 0x20;
x = LOW_BYTE(spriteram[offs + 3]) * 2 + m_sprite_xoffset;
y = (241 - LOW_BYTE(spriteram[offs])) * 2;
/* allow sprites to clip off the left side */
if (x > 0x1f0) x -= 0x200;
/* sprites use color 0 for background pen and 8 for the 'under tile' pen.
The color 8 is used to cover over other sprites. */
/* first draw the sprite, visible */
m_gfxdecode->gfx(1)->prio_transmask(bitmap,sprite_clip, code, color, flipx, flipy, x, y,
screen.priority(), 0x00, 0x0101);
/* then draw the mask, behind the background but obscuring following sprites */
m_gfxdecode->gfx(1)->prio_transmask(bitmap,sprite_clip, code, color, flipx, flipy, x, y,
screen.priority(), 0x02, 0xfeff);
}
}
/*************************************
*
* General MCR/68k update
*
*************************************/
uint32_t mcr68_state::screen_update_mcr68(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
/* draw the background */
m_bg_tilemap->draw(screen, bitmap, cliprect, TILEMAP_DRAW_OPAQUE | TILEMAP_DRAW_ALL_CATEGORIES, 0);
/* draw the low-priority sprites */
mcr68_update_sprites(screen, bitmap, cliprect, 0);
/* redraw tiles with priority over sprites */
m_bg_tilemap->draw(screen, bitmap, cliprect, 1, 0);
/* draw the high-priority sprites */
mcr68_update_sprites(screen, bitmap, cliprect, 1);
return 0;
}