i8244: split big screen_update function into several pieces

src/devices/video/i8244.cpp

@@ -4,8 +4,16 @@
 /***************************************************************************
 
 Intel 8244 (NTSC)/8245 (PAL) Graphics and sound chip
+Exclusively used in Odyssey 2 series.
 
-Exclusively used in Odyssey 2 series. See driver file for known problems.
+Features summary:
+- 9*8 grid
+- major system (predefined 8*7 objects, 12 single + 4 quads)
+- minor system (4 user-defined 8*8 sprites)
+- collision detection between all layers
+- 1-bit sound
+
+See Odyssey 2 driver file for known problems.
 
 ***************************************************************************/
 
@@ -26,9 +34,7 @@ DEFINE_DEVICE_TYPE(I8245, i8245_device, "i8245", "Intel 8245")
 
 i8244_device::i8244_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
 	: i8244_device(mconfig, I8244, tag, owner, clock)
-{
+{ }
-}
-
 
 i8244_device::i8244_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock)
 	: device_t(mconfig, type, tag, owner, clock)
@@ -36,13 +42,24 @@ i8244_device::i8244_device(const machine_config &mconfig, device_type type, cons
 	, device_video_interface(mconfig, *this)
 	, m_irq_func(*this)
 	, m_charset(*this, "cgrom")
-{
+{ }
-}
-
 
 i8245_device::i8245_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
 	: i8244_device(mconfig, I8245, tag, owner, clock)
+{ }
+
+
+//-------------------------------------------------
+//  device configuration
+//-------------------------------------------------
+
+void i8244_device::device_config_complete()
 {
+	if (!has_screen())
+		return;
+
+	if (!screen().refresh_attoseconds())
+		screen().set_raw(clock()*2, m_htotal, m_cropx, m_cropx + m_width, m_vtotal, m_cropy, m_cropy + m_height);
 }
 
 void i8244_device::set_default_params()
@@ -90,7 +107,6 @@ ROM_START( i8244 )
 	ROM_LOAD( "charset_i8244.bin", 0x0000, 0x0200, CRC(b46a3f31) SHA1(415382715455b47b69401b3d60bd8f0036dd7fef) )
 ROM_END
 
-
 const tiny_rom_entry *i8244_device::device_rom_region() const
 {
 	return ROM_NAME( i8244 );
@@ -98,18 +114,33 @@ const tiny_rom_entry *i8244_device::device_rom_region() const
 
 
 //-------------------------------------------------
-//  device_config_complete - perform any
+//  i8244_palette - default palette
-//  operations now that the configuration is
-//  complete
 //-------------------------------------------------
 
-void i8244_device::device_config_complete()
+void i8244_device::i8244_palette(palette_device &palette) const
 {
-	if (!has_screen())
+	// RGB output, before any NTSC/PAL RF encoder
-		return;
+	static constexpr rgb_t i8244_colors[16] =
+	{
+		{ 0x00, 0x00, 0x00 }, // i r g b
+		{ 0xb6, 0x00, 0x00 }, // i R g b
+		{ 0x00, 0xb6, 0x00 }, // i r G b
+		{ 0xb6, 0xb6, 0x00 }, // i R G b
+		{ 0x00, 0x00, 0xb6 }, // i r g B
+		{ 0xb6, 0x00, 0xb6 }, // i R g B
+		{ 0x00, 0xb6, 0xb6 }, // i r G B
+		{ 0xb6, 0xb6, 0xb6 }, // i R G B
+		{ 0x49, 0x49, 0x49 }, // I r g b
+		{ 0xff, 0x49, 0x49 }, // I R g b
+		{ 0x49, 0xff, 0x49 }, // I r G b
+		{ 0xff, 0xff, 0x49 }, // I R G b
+		{ 0x49, 0x49, 0xff }, // I r g B
+		{ 0xff, 0x49, 0xff }, // I R g B
+		{ 0x49, 0xff, 0xff }, // I r G B
+		{ 0xff, 0xff, 0xff }  // I R G B
+	};
 
-	if (!screen().refresh_attoseconds())
+	palette.set_pen_colors(0, i8244_colors);
-		screen().set_raw(clock()*2, m_htotal, m_cropx, m_cropx + m_width, m_vtotal, m_cropy, m_cropy + m_height);
 }
 
 
@@ -153,32 +184,9 @@ void i8244_device::device_start()
 }
 
 
-void i8244_device::i8244_palette(palette_device &palette) const
+//-------------------------------------------------
-{
+//  device_timer - handle timer callbacks
-	// RGB output, before any NTSC/PAL RF encoder
+//-------------------------------------------------
-	static constexpr rgb_t i8244_colors[16] =
-	{
-		{ 0x00, 0x00, 0x00 }, // i r g b
-		{ 0xb6, 0x00, 0x00 }, // i R g b
-		{ 0x00, 0xb6, 0x00 }, // i r G b
-		{ 0xb6, 0xb6, 0x00 }, // i R G b
-		{ 0x00, 0x00, 0xb6 }, // i r g B
-		{ 0xb6, 0x00, 0xb6 }, // i R g B
-		{ 0x00, 0xb6, 0xb6 }, // i r G B
-		{ 0xb6, 0xb6, 0xb6 }, // i R G B
-		{ 0x49, 0x49, 0x49 }, // I r g b
-		{ 0xff, 0x49, 0x49 }, // I R g b
-		{ 0x49, 0xff, 0x49 }, // I r G b
-		{ 0xff, 0xff, 0x49 }, // I R G b
-		{ 0x49, 0x49, 0xff }, // I r g B
-		{ 0xff, 0x49, 0xff }, // I R g B
-		{ 0x49, 0xff, 0xff }, // I r G B
-		{ 0xff, 0xff, 0xff }  // I R G B
-	};
-
-	palette.set_pen_colors(0, i8244_colors);
-}
-
 
 void i8244_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
 {
@@ -201,6 +209,10 @@ void i8244_device::device_timer(emu_timer &timer, device_timer_id id, int param,
 }
 
 
+/***************************************************************************
+    I/O
+***************************************************************************/
+
 offs_t i8244_device::fix_register_mirrors(offs_t offset)
 {
 	// quad x/y registers are mirrored for each quad
@@ -472,58 +484,12 @@ void i8244_device::write_cx(int x, bool cx)
 }
 
 
-void i8244_device::draw_char(u8 index, int x, int y, u8 pixel, u16 color, bitmap_ind16 &bitmap, const rectangle &cliprect)
+/***************************************************************************
+    RENDER
+***************************************************************************/
+
+void i8244_device::draw_grid(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect)
 {
-	for (int px = x; px < x + 2; px++)
-	{
-		if (cliprect.contains(px, y))
-		{
-			u8 colx = m_collision_map[px];
-
-			// check collision with self
-			if (index < m_priority_map[px])
-			{
-				m_control_status |= 0x80;
-
-				// TODO: much more complex on actual console (weird glitches happen)
-				if (colx & 0x80)
-					continue;
-			}
-			else
-				m_priority_map[px] = index;
-
-			if (pixel)
-			{
-				// check if we collide with an already drawn source object
-				if (m_vdc.s.collision & colx)
-					m_collision_status |= 0x80;
-
-				// check if an already drawn object would collide with us
-				if (m_vdc.s.collision & 0x80)
-					m_collision_status |= colx;
-
-				m_collision_map[px] |= 0x80;
-				bitmap.pix(y, px) = color;
-			}
-		}
-	}
-}
-
-
-u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
-{
-	// draw background color
-	bitmap.fill(bitswap<3>(m_vdc.s.color,3,4,5), cliprect);
-
-	for (int scanline = cliprect.min_y; scanline <= cliprect.max_y; scanline++)
-	{
-		// clear collision maps
-		memset(m_collision_map, 0, sizeof(m_collision_map));
-		memset(m_priority_map, 0, sizeof(m_priority_map));
-
-		// display grid if enabled
-		if (m_vdc.s.control & 0x08)
-		{
 	u16 color = bitswap<4>(m_vdc.s.color,6,0,1,2);
 	int x_grid_offset = 13;
 	int y_grid_offset = 24;
@@ -611,11 +577,49 @@ u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, con
 			}
 		}
 	}
-		}
+}
 
-		// display objects if enabled
+
-		if (m_vdc.s.control & 0x20 && scanline <= 242)
+void i8244_device::char_pixel(u8 index, int x, int y, u8 pixel, u16 color, bitmap_ind16 &bitmap, const rectangle &cliprect)
+{
+	for (int px = x; px < x + 2; px++)
 	{
+		if (cliprect.contains(px, y))
+		{
+			u8 colx = m_collision_map[px];
+
+			// check collision with self
+			if (index < m_priority_map[px])
+			{
+				m_control_status |= 0x80;
+
+				// TODO: much more complex on actual console (weird glitches happen)
+				if (colx & 0x80)
+					continue;
+			}
+			else
+				m_priority_map[px] = index;
+
+			if (pixel)
+			{
+				// check if we collide with an already drawn source object
+				if (m_vdc.s.collision & colx)
+					m_collision_status |= 0x80;
+
+				// check if an already drawn object would collide with us
+				if (m_vdc.s.collision & 0x80)
+					m_collision_status |= colx;
+
+				m_collision_map[px] |= 0x80;
+				bitmap.pix(y, px) = color;
+			}
+		}
+	}
+}
+
+
+void i8244_device::draw_major(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect)
+{
 	// quad objects
 	for (int i = ARRAY_LENGTH(m_vdc.s.quad) - 1; i >= 0; i--)
 	{
@@ -637,7 +641,7 @@ u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, con
 
 				u16 color = 8 + ((m_vdc.s.quad[i].single[j].color >> 1) & 0x07);
 				for (int cx = 0; cx < 8; cx++, x += 2)
-							draw_char(4 * j + 16 * i + 0x40, x, scanline, BIT(m_charset[offset & 0x1ff], cx ^ 7), color, bitmap, cliprect);
+					char_pixel(4 * j + 16 * i + 0x40, x, scanline, BIT(m_charset[offset & 0x1ff], cx ^ 7), color, bitmap, cliprect);
 			}
 		}
 	}
@@ -659,11 +663,15 @@ u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, con
 			int x = (m_vdc.s.foreground[i].x + 5) * 2;
 			u16 color = 8 + ((m_vdc.s.foreground[i].color >> 1) & 0x07);
 			for (int cx = 0; cx < 8; cx++, x += 2)
-						draw_char(4 * i + 0x10, x, scanline, BIT(m_charset[offset & 0x1ff], cx ^ 7), color, bitmap, cliprect);
+				char_pixel(4 * i + 0x10, x, scanline, BIT(m_charset[offset & 0x1ff], cx ^ 7), color, bitmap, cliprect);
 		}
 	}
+}
 
-			// sprites
+
+void i8244_device::draw_minor(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect)
+{
+	// minor system (sprites)
 	for (int i = ARRAY_LENGTH(m_vdc.s.sprites) - 1; i >= 0; i--)
 	{
 		int y = m_vdc.s.sprites[i].y;
@@ -721,6 +729,29 @@ u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, con
 			}
 		}
 	}
+}
+
+
+u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
+{
+	// draw background color
+	bitmap.fill(bitswap<3>(m_vdc.s.color,3,4,5), cliprect);
+
+	for (int scanline = cliprect.min_y; scanline <= cliprect.max_y; scanline++)
+	{
+		// clear collision maps
+		memset(m_collision_map, 0, sizeof(m_collision_map));
+		memset(m_priority_map, 0, sizeof(m_priority_map));
+
+		// display grid if enabled
+		if (m_vdc.s.control & 0x08 && scanline >= 24 && scanline <= 218)
+			draw_grid(scanline, bitmap, cliprect);
+
+		// display objects if enabled
+		if (m_vdc.s.control & 0x20 && scanline <= 242)
+		{
+			draw_major(scanline, bitmap, cliprect);
+			draw_minor(scanline, bitmap, cliprect);
 		}
 	}
 
@@ -728,6 +759,10 @@ u32 i8244_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, con
 }
 
 
+/***************************************************************************
+    SOUND
+***************************************************************************/
+
 void i8244_device::sound_stream_update(sound_stream &stream, std::vector<read_stream_view> const &inputs, std::vector<write_stream_view> &outputs)
 {
 	u8 volume = m_vdc.s.sound & 0xf;

src/devices/video/i8244.h

@@ -124,7 +124,10 @@ protected:
 	offs_t fix_register_mirrors(offs_t offset);
 	bool invalid_register(offs_t offset, bool rw);
 
-	void draw_char(u8 index, int x, int y, u8 pixel, u16 color, bitmap_ind16 &bitmap, const rectangle &cliprect);
+	void draw_grid(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect);
+	void draw_major(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect);
+	void draw_minor(int scanline, bitmap_ind16 &bitmap, const rectangle &cliprect);
+	void char_pixel(u8 index, int x, int y, u8 pixel, u16 color, bitmap_ind16 &bitmap, const rectangle &cliprect);
 
 	/* timers */
 	static constexpr device_timer_id TIMER_VBLANK_START = 0;