cave.cpp : Implement hardware sprite limitation, Add notes

src/mame/includes/cave.h

@@ -255,6 +255,7 @@ private:
 
 	u16       m_sprite_base_pal;
 	u16       m_sprite_granularity;
+	u32       m_max_sprite_clk[4]; // max usable clock for sprites
 
 	/* misc */
 	int       m_time_vblank_irq;

src/mame/video/cave.cpp

@@ -162,15 +162,15 @@ VIDEO_START_MEMBER(cave_state,ppsatan)
 
 /***************************************************************************
 
-                                Sprites Drawing
+                            Zoomed Sprites Drawing
+
+	Sprite format with zoom, 16 bytes per each sprites
 
     Offset:     Bits:                   Value:
 
-    00.w        fedc ba98 76-- ----     X Position
-                ---- ---- --54 3210
+    00.w                                X Position*
 
-    02.w        fedc ba98 76-- ----     Y Position
-                ---- ---- --54 3210
+    02.w                                Y Position*
 
     04.w        fe-- ---- ---- ----
                 --dc ba98 ---- ----     Color
@@ -189,6 +189,42 @@ VIDEO_START_MEMBER(cave_state,ppsatan)
 
     0E.w                                Unused
 
+	* S.9.6 Fixed point or 10 bit signed integer,
+	  Configured from videoregs
+
+
+                                Sprites Drawing
+
+	Sprite format without zoom, 16 bytes per each sprites
+
+    Offset:     Bits:                   Value:
+
+    00.w        fe-- ---- ---- ----
+                --dc ba98 ---- ----     Color
+                ---- ---- 76-- ----
+                ---- ---- --54 ----     Priority
+                ---- ---- ---- 3---     Flip X
+                ---- ---- ---- -2--     Flip Y
+                ---- ---- ---- --10     Code High Bit(s?)
+
+    02.w                                Code Low Bits
+
+    04.w        fedc ba-- ---- ----
+                ---- --98 7654 3210     X Position**
+
+    06.w        fedc ba-- ---- ----
+                ---- --98 7654 3210     Y Position**
+
+    08.w        fedc ba98 ---- ----     Tile Size X
+                ---- ---- 7654 3210     Tile Size Y
+
+    0A.w                                Unused
+
+    0C.w                                Unused
+
+    0E.w                                Unused
+
+	** 10 bit signed only? need verifications.
 
 ***************************************************************************/
 
@@ -211,9 +247,14 @@ void cave_state::get_sprite_info_cave(int chip)
 
 	const u16 *source = m_spriteram[chip] + (0x4000 / 2) * m_spriteram_bank[chip];
 	const u16 *finish = source + (0x4000 / 2);
+	u32 clk = 0; // used clock cycle for sprites
 
 	for (; source < finish; source += 8)
 	{
+		clk += 32; // 32 clock per each sprites
+		if (clk > m_max_sprite_clk[chip])
+			break;
+
 		int x, y;
 		int total_width_f, total_height_f;
 
@@ -239,6 +280,10 @@ void cave_state::get_sprite_info_cave(int chip)
 		if (!sprite->tile_width || !sprite->tile_height)
 			continue;
 
+		clk += sprite->tile_width * sprite->tile_height; // 256 clock per each sprite blocks
+		if (clk > m_max_sprite_clk[chip])
+			break;
+
 		/* Bound checking */
 		code %= code_max;
 		sprite->pen_data = base_gfx + (16 * 16) * code;
@@ -334,9 +379,14 @@ void cave_state::get_sprite_info_donpachi(int chip)
 
 	const u16 *source = m_spriteram[chip] + (0x4000 / 2) * m_spriteram_bank[chip];
 	const u16 *finish = source + (0x4000 / 2);
+	u32 clk = 0; // used clock cycle for sprites
 
 	for (; source < finish; source += 8)
 	{
+		clk += 32; // 32 clock per each sprites
+		if (clk > m_max_sprite_clk[chip])
+			break;
+
 		int y;
 
 		const u16 attr = source[0];
@@ -364,6 +414,10 @@ void cave_state::get_sprite_info_donpachi(int chip)
 			x + sprite->total_width <= 0 || x >= max_x || y + sprite->total_height <= 0 || y >= max_y)
 		{continue;}
 
+		clk += sprite->tile_width * sprite->tile_height; // 256 clock per each sprite blocks
+		if (clk > m_max_sprite_clk[chip])
+			break;
+
 		int flipx    = attr & 0x0008;
 		int flipy    = attr & 0x0004;
 
@@ -422,8 +476,20 @@ void cave_state::sprite_init()
 
 	for (int chip = 0; chip < 4; chip++)
 	{
+		m_max_sprite_clk[chip] = 0;
 		if (m_videoregs[chip])
 		{
+			for (int screen = 0; screen < 4; screen++)
+			{
+				if (m_screen[screen])
+				{
+					const u32 new_clk = (m_screen[screen]->visible_area().width() > 360 ? 512 : 448) * 272 * 2; // whole screen size related?
+					if (m_max_sprite_clk[chip] < new_clk)
+					{
+						m_max_sprite_clk[chip] = new_clk;
+					}
+				}
+			}
 			m_num_sprites[chip] = m_spriteram[chip].bytes() / 0x10 / 2;
 			m_sprite[chip] = std::make_unique<sprite_cave []>(m_num_sprites[chip]);
 		}
@@ -840,7 +906,8 @@ void cave_state::do_blit_32(int chip, const sprite_cave *sprite)
 			return;
 		y1--; y2--;
 	}
-	else {
+	else
+	{
 		y1 = sprite->y;
 		y2 = y1 + sprite->total_height;
 		dy = 1;
@@ -1038,7 +1105,7 @@ void cave_state::sprite_draw_donpachi_zbuf(int chip, int priority)
                                 Screen Drawing
 
 
-                Layers Control Registers (cave_vctrl_0..2)
+                  Layers Control Registers (vctrl_0..3)
 
 
         Offset:     Bits:                   Value:
@@ -1069,7 +1136,7 @@ void cave_state::sprite_draw_donpachi_zbuf(int chip, int priority)
         Row-scroll:     a different scroll value is specified for each scan line.
 
 
-                    Sprites Registers (cave_videoregs)
+                      Sprites Registers (videoregs)
 
 
     Offset:     Bits:                   Value:
@@ -1338,6 +1405,7 @@ void cave_state::get_sprite_info(int chip)
 		}
 	}
 }
+
 void cave_state::device_post_load()
 {
 	for (int chip = 0; chip < 4; chip++)