// license:BSD-3-Clause // copyright-holders:Aaron Giles /*************************************************************************** Atari Skull & Crossbones hardware ****************************************************************************/ #include "emu.h" #include "includes/skullxbo.h" /************************************* * * Tilemap callbacks * *************************************/ TILE_GET_INFO_MEMBER(skullxbo_state::get_alpha_tile_info) { uint16_t data = m_alpha_tilemap->basemem_read(tile_index); int code = (data ^ 0x400) & 0x7ff; int color = (data >> 11) & 0x0f; int opaque = data & 0x8000; SET_TILE_INFO_MEMBER(2, code, color, opaque ? TILE_FORCE_LAYER0 : 0); } TILE_GET_INFO_MEMBER(skullxbo_state::get_playfield_tile_info) { uint16_t data1 = m_playfield_tilemap->basemem_read(tile_index); uint16_t data2 = m_playfield_tilemap->extmem_read(tile_index) & 0xff; int code = data1 & 0x7fff; int color = data2 & 0x0f; SET_TILE_INFO_MEMBER(1, code, color, (data1 >> 15) & 1); } /************************************* * * Video system start * *************************************/ const atari_motion_objects_config skullxbo_state::s_mob_config = { 0, /* index to which gfx system */ 2, /* number of motion object banks */ 1, /* 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? */ 8, /* pixels per SLIP entry (0 for no-slip) */ 0, /* pixel offset for SLIPs */ 0, /* maximum number of links to visit/scanline (0=all) */ 0x000, /* base palette entry */ 0x200, /* maximum number of colors */ 0, /* transparent pen index */ {{ 0x00ff,0,0,0 }}, /* mask for the link */ {{ 0,0x7fff,0,0 }}, /* mask for the code index */ {{ 0,0,0x000f,0 }}, /* mask for the color */ {{ 0,0,0xffc0,0 }}, /* mask for the X position */ {{ 0,0,0,0xff80 }}, /* mask for the Y position */ {{ 0,0,0,0x0070 }}, /* mask for the width, in tiles*/ {{ 0,0,0,0x000f }}, /* mask for the height, in tiles */ {{ 0,0x8000,0,0 }}, /* mask for the horizontal flip */ {{ 0 }}, /* mask for the vertical flip */ {{ 0,0,0x0030,0 }}, /* 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" */ }; /************************************* * * Video data latch * *************************************/ WRITE16_MEMBER( skullxbo_state::skullxbo_xscroll_w ) { /* combine data */ uint16_t oldscroll = *m_xscroll; uint16_t newscroll = oldscroll; COMBINE_DATA(&newscroll); /* if something changed, force an update */ if (oldscroll != newscroll) m_screen->update_partial(m_screen->vpos()); /* adjust the actual scrolls */ m_playfield_tilemap->set_scrollx(0, 2 * (newscroll >> 7)); m_mob->set_xscroll(2 * (newscroll >> 7)); /* update the data */ *m_xscroll = newscroll; } WRITE16_MEMBER( skullxbo_state::skullxbo_yscroll_w ) { /* combine data */ int scanline = m_screen->vpos(); uint16_t oldscroll = *m_yscroll; uint16_t newscroll = oldscroll; uint16_t effscroll; COMBINE_DATA(&newscroll); /* if something changed, force an update */ if (oldscroll != newscroll) m_screen->update_partial(scanline); /* adjust the effective scroll for the current scanline */ if (scanline > m_screen->visible_area().max_y) scanline = 0; effscroll = (newscroll >> 7) - scanline; /* adjust the actual scrolls */ m_playfield_tilemap->set_scrolly(0, effscroll); m_mob->set_yscroll(effscroll & 0x1ff); /* update the data */ *m_yscroll = newscroll; } /************************************* * * Motion object bank handler * *************************************/ WRITE16_MEMBER( skullxbo_state::skullxbo_mobmsb_w ) { m_screen->update_partial(m_screen->vpos()); m_mob->set_bank((offset >> 9) & 1); } /************************************* * * Playfield latch write handler * *************************************/ WRITE16_MEMBER( skullxbo_state::playfield_latch_w ) { m_playfield_latch = data; } WRITE16_MEMBER(skullxbo_state::playfield_latched_w) { m_playfield_tilemap->write16(space, offset, data, mem_mask); if (m_playfield_latch != -1) { uint16_t oldval = m_playfield_tilemap->extmem_read(offset); uint16_t newval = (oldval & ~0x00ff) | (m_playfield_latch & 0x00ff); m_playfield_tilemap->extmem_write(offset, newval); } } /************************************* * * Periodic playfield updater * *************************************/ void skullxbo_state::skullxbo_scanline_update(int scanline) { int x; /* keep in range */ int offset = (scanline / 8) * 64 + 42; if (offset >= 0x7c0) return; /* special case: scanline 0 should re-latch the previous raw scroll */ if (scanline == 0) { int newscroll = (*m_yscroll >> 7) & 0x1ff; m_playfield_tilemap->set_scrolly(0, newscroll); m_mob->set_yscroll(newscroll); } /* update the current parameters */ for (x = 42; x < 64; x++) { uint16_t data = m_alpha_tilemap->basemem_read(offset++); uint16_t command = data & 0x000f; /* only command I've ever seen */ if (command == 0x0d) { /* a new vscroll latches the offset into a counter; we must adjust for this */ int newscroll = ((data >> 7) - scanline) & 0x1ff; /* force a partial update with the previous scroll */ if (scanline > 0) m_screen->update_partial(scanline - 1); /* update the new scroll */ m_playfield_tilemap->set_scrolly(0, newscroll); m_mob->set_yscroll(newscroll); /* make sure we change this value so that writes to the scroll register */ /* know whether or not they are a different scroll */ *m_yscroll = data; } } } /************************************* * * Main refresh * *************************************/ uint32_t skullxbo_state::screen_update_skullxbo(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->min_y; y <= rect->max_y; y++) { uint16_t *mo = &mobitmap.pix16(y); uint16_t *pf = &bitmap.pix16(y); for (int x = rect->min_x; x <= rect->max_x; x++) if (mo[x] != 0xffff) { /* verified from the GALs on the real PCB; equations follow --- O17 is an intermediate value O17=PFPIX3*PFPAL2S*PFPAL3S --- CRAM.A10 controls the high bit of the palette select; used for shadows CRAM.A10=BA11*CRAMD +!CRAMD*!LBPRI0*!LBPRI1*!O17*(LBPIX==1)*(ANPIX==0) +!CRAMD*LBPRI0*!LBPRI1*(LBPIX==1)*(ANPIX==0)*!PFPAL3S +!CRAMD*LBPRI1*(LBPIX==1)*(ANPIX==0)*!PFPAL2S*!PFPAL3S +!CRAMD*!PFPIX3*(LBPIX==1)*(ANPIX==0) --- SA and SB are the mux select lines: --- 0 = motion objects --- 1 = playfield --- 2 = alpha --- 3 = color RAM access from CPU !SA=!CRAMD*(ANPIX!=0) +!CRAMD*!LBPRI0*!LBPRI1*!O17*(LBPIX!=1)*(LBPIX!=0) +!CRAMD*LBPRI0*!LBPRI1*(LBPIX!=1)*(LBPIX!=0)*!PFPAL3S +!CRAMD*LBPRI1*(LBPIX!=1)*(LBPIX!=0)*!PFPAL2S*!PFPAL3S +!CRAMD*!PFPIX3*(LBPIX!=1)*(LBPIX!=0) !SB=!CRAMD*(ANPIX==0) +!CRAMD*LBMISC*(LBPIX!=0) */ int mopriority = mo[x] >> atari_motion_objects_device::PRIORITY_SHIFT; int mopix = mo[x] & 0x1f; int pfcolor = (pf[x] >> 4) & 0x0f; int pfpix = pf[x] & 0x0f; int o17 = ((pf[x] & 0xc8) == 0xc8); /* implement the equations */ if ((mopriority == 0 && !o17 && mopix >= 2) || (mopriority == 1 && mopix >= 2 && !(pfcolor & 0x08)) || ((mopriority & 2) && mopix >= 2 && !(pfcolor & 0x0c)) || (!(pfpix & 8) && mopix >= 2)) pf[x] = mo[x] & atari_motion_objects_device::DATA_MASK; if ((mopriority == 0 && !o17 && mopix == 1) || (mopriority == 1 && mopix == 1 && !(pfcolor & 0x08)) || ((mopriority & 2) && mopix == 1 && !(pfcolor & 0x0c)) || (!(pfpix & 8) && mopix == 1)) pf[x] |= 0x400; } } /* add the alpha on top */ m_alpha_tilemap->draw(screen, bitmap, cliprect, 0, 0); return 0; }