chqflag.cpp: k051937 actually sets up a register when background should be dimmed, fixes start/end pouring event colors [Angelo Salese]

src/mame/drivers/chqflag.cpp

@@ -57,14 +57,6 @@ WRITE8_MEMBER(chqflag_state::chqflag_bankswitch_w)
 	/* other bits unknown/unused */
 }
 
-inline void chqflag_state::update_background_shadows(uint8_t data)
-{
-	double brt = (data & 0x80) ? PALETTE_DEFAULT_SHADOW_FACTOR : 1.0;
-
-	for (int i = 512; i < 1024; i++)
-		m_palette->set_pen_contrast(i, brt);
-}
-
 WRITE8_MEMBER(chqflag_state::chqflag_vreg_w)
 {
 	/* bits 0 & 1 = coin counters */
@@ -86,12 +78,13 @@ WRITE8_MEMBER(chqflag_state::chqflag_vreg_w)
 	 * 0x88 is for when night shows up (max amount of highlight)
 	 * 0x08 is used at dawn after 0x88 state
 	 * The shadow part looks ugly when rain starts/ends pouring (-> black colored with a setting of 0x00), 
-	 * apparently the reference shows dimmed background when car pits in which maybe translates in a 
+	 * the reference shows dimmed background when this event occurs (which is handled via reg 1 bit 0 of k051960 device), 
-	 * global zoomed sprite that gets clipped in emulation?
+	 * might be actually disabling the shadow here (-> setting 1.0f instead), but can't say for sure from the available reference.
 	 */
 	const float shadow_factors[4] = {PALETTE_DEFAULT_SHADOW_FACTOR, 1.33f, 1.66f, 2.0f };
 	m_palette->set_shadow_factor(shadow_factors[((data & 0x80) >> 6) | ((data & 0x08) >> 3)]);
 	
+	#if 0
 	if ((data & 0x80) != m_last_vreg)
 	{
 		m_last_vreg = data & 0x80;
@@ -99,6 +92,7 @@ WRITE8_MEMBER(chqflag_state::chqflag_vreg_w)
 		/* only affect the background */
 		update_background_shadows(data);
 	}
+	#endif
 	
 //if ((data & 0xf8) && (data & 0xf8) != 0x88)
 //  popmessage("chqflag_vreg_w %02x",data);
@@ -301,6 +295,26 @@ void chqflag_state::machine_reset()
 	update_background_shadows(0);
 }
 
+inline void chqflag_state::update_background_shadows(uint8_t data)
+{
+	double brt = (data & 1) ? PALETTE_DEFAULT_SHADOW_FACTOR : 1.0;
+
+	for (int i = 512; i < 1024; i++)
+		m_palette->set_pen_contrast(i, brt);
+}
+
+
+WRITE_LINE_MEMBER(chqflag_state::background_brt_w)
+{
+//	popmessage("%d",state);
+	
+	if (state != m_last_vreg)
+	{
+		m_last_vreg = state;
+		update_background_shadows(state);
+	}
+}
+
 static MACHINE_CONFIG_START( chqflag )
 
 	/* basic machine hardware */
@@ -339,6 +353,7 @@ static MACHINE_CONFIG_START( chqflag )
 	MCFG_K051960_CB(chqflag_state, sprite_callback)
 	MCFG_K051960_IRQ_HANDLER(INPUTLINE("maincpu", KONAMI_IRQ_LINE))
 	MCFG_K051960_NMI_HANDLER(INPUTLINE("maincpu", INPUT_LINE_NMI))
+	MCFG_K051960_VREG_CONTRAST_HANDLER(WRITELINE(chqflag_state,background_brt_w))
 	
 	MCFG_DEVICE_ADD("k051316_1", K051316, 0)
 	MCFG_GFX_PALETTE("palette")

src/mame/includes/chqflag.h

@@ -41,6 +41,7 @@ public:
 	DECLARE_WRITE8_MEMBER(k007232_extvolume_w);
 	DECLARE_WRITE8_MEMBER(volume_callback0);
 	DECLARE_WRITE8_MEMBER(volume_callback1);
+	DECLARE_WRITE_LINE_MEMBER(background_brt_w);
 	K051316_CB_MEMBER(zoom_callback_1);
 	K051316_CB_MEMBER(zoom_callback_2);
 	K051960_CB_MEMBER(sprite_callback);

src/mame/video/k051960.cpp

@@ -38,6 +38,7 @@ memory map:
 001     W  Devastators sets bit 1, function unknown.
            Ultraman sets the register to 0x0f.
            None of the other games I tested seem to set this register to other than 0.
+		   Update: Chequered Flag sets bit 0 when background should be dimmed (palette control?)
 002-003 W  selects the portion of the gfx ROMs to be read.
 004     W  Aliens uses this to select the ROM bank to be read, but Punk Shot
            and TMNT don't, they use another bit of the registers above. Many
@@ -136,6 +137,7 @@ k051960_device::k051960_device(const machine_config &mconfig, const char *tag, d
 	, m_irq_handler(*this)
 	, m_firq_handler(*this)
 	, m_nmi_handler(*this)
+	, m_vreg_contrast_handler(*this)
 	, m_romoffset(0)
 	, m_spriteflip(0)
 	, m_readroms(0)
@@ -207,6 +209,7 @@ void k051960_device::device_start()
 	m_irq_handler.resolve_safe();
 	m_firq_handler.resolve_safe();
 	m_nmi_handler.resolve_safe();
+	m_vreg_contrast_handler.resolve_safe();
 
 	// register for save states
 	save_item(NAME(m_romoffset));
@@ -330,6 +333,10 @@ WRITE8_MEMBER( k051960_device::k051937_w )
 	}
 	else if (offset == 1)
 	{
+		//popmessage("%04x: write %02x to 051937 address %x", space.device().safe_pc(), data, offset);
+		// Chequered Flag uses this bit to enable background palette dimming
+		// TODO: use a callback here for now, pending further investigation over this bit
+		m_vreg_contrast_handler(BIT(data,0));
 		// unknown, Devastators writes 02 here in game
 		if (0)
 			logerror("%s: %02x to 051937 address %x\n", machine().describe_context(), data, offset);

src/mame/video/k051960.h

@@ -33,6 +33,9 @@ typedef device_delegate<void (int *code, int *color, int *priority, int *shadow)
 #define MCFG_K051960_NMI_HANDLER(_devcb) \
 	devcb = &k051960_device::set_nmi_handler(*device, DEVCB_##_devcb);
 
+#define MCFG_K051960_VREG_CONTRAST_HANDLER(_devcb) \
+	devcb = &k051960_device::set_vreg_contrast_handler(*device, DEVCB_##_devcb);
+
 
 class k051960_device : public device_t, public device_gfx_interface
 {
@@ -52,6 +55,10 @@ public:
 	template <class Object> static devcb_base &set_nmi_handler(device_t &device, Object &&cb)
 	{ return downcast<k051960_device &>(device).m_nmi_handler.set_callback(std::forward<Object>(cb)); }
 
+	template <class Object> static devcb_base &set_vreg_contrast_handler(device_t &device, Object &&cb)
+	{ return downcast<k051960_device &>(device).m_vreg_contrast_handler.set_callback(std::forward<Object>(cb)); }
+
+	
 	// static configuration
 	static void set_k051960_callback(device_t &device, k051960_cb_delegate callback) { downcast<k051960_device &>(device).m_k051960_cb = callback; }
 	static void set_plane_order(device_t &device, int order);
@@ -98,8 +105,10 @@ private:
 	k051960_cb_delegate m_k051960_cb;
 
 	devcb_write_line m_irq_handler;
+	// TODO: is this even used by anything?
 	devcb_write_line m_firq_handler;
 	devcb_write_line m_nmi_handler;
+	devcb_write_line m_vreg_contrast_handler;
 
 	uint8_t    m_spriterombank[3];
 	int      m_romoffset;