bus/nes: Fixed non-working Whirlwind LE10 SMB2 FDS conversion. (#8361)

Software list items promoted to working (nes.xml)
---------------------------------------
Super Mario Bros. 2 (LE10)

hash/nes.xml

@@ -67226,8 +67226,8 @@ Also notice that VRAM & WRAM are probably incorrect for some of these sets, at t
 		</part>
 	</software>
 
-<!-- Whirlwind Manu has at least two version: LE10 and LF36. This earlier version apparently hangs at the end of world 4-4 on real hardware. -->
-	<software name="smb2fdse" cloneof="smb2fds" supported="no">
+<!-- Whirlwind Manu has at least two versions: LE10 and LF36. This earlier version has a broken status bar that scrolls with the game. It also crashes at the end of world 4-4 on real hardware (and in MAME). -->
+	<software name="smb2fdse" cloneof="smb2fds">
 		<description>Super Mario Bros. 2 (LE10)</description>
 		<year>19??</year>
 		<publisher>Whirlwind Manu</publisher>

src/devices/bus/nes/bootleg.cpp

@@ -117,8 +117,8 @@ nes_0353_device::nes_0353_device(const machine_config &mconfig, const char *tag,
 {
 }
 
-nes_09034a_device::nes_09034a_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
-	: nes_nrom_device(mconfig, NES_09034A, tag, owner, clock), m_reg(0)
+nes_09034a_device::nes_09034a_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
+	: nes_nrom_device(mconfig, NES_09034A, tag, owner, clock), m_irq_count(0), m_irq_enable(0), m_reg(0), irq_timer(nullptr)
 {
 }
 
@@ -434,6 +434,11 @@ void nes_0353_device::pcb_reset()
 void nes_09034a_device::device_start()
 {
 	common_start();
+	irq_timer = timer_alloc(TIMER_IRQ);
+	irq_timer->adjust(attotime::zero, 0, clocks_to_attotime(1));
+
+	save_item(NAME(m_irq_enable));
+	save_item(NAME(m_irq_count));
 	save_item(NAME(m_reg));
 }
 
@@ -442,6 +447,9 @@ void nes_09034a_device::pcb_reset()
 	m_chr_source = m_vrom_chunks ? CHRROM : CHRRAM;
 	prg32(0);
 	chr8(0, m_chr_source);
+
+	m_irq_enable = 0;
+	m_irq_count = 0;
 	m_reg = 0;
 }
 
@@ -1304,30 +1312,76 @@ void nes_0353_device::write_h(offs_t offset, u8 data)
  (UNL-)09-034A
 
  Games: Zanac FDS conversion with two PRG chips and
- no CHRROM and Volleyball FDS conversion with two PRG
- chips and CHRROM.
- Originally dumps were marked as UNL-SMB2J pcb
+ no CHRROM, and SMB2 and Volleyball FDS conversions
+ with two PRG chips and CHRROM. Originally dumps
+ were marked as UNL-SMB2J PCB.
+
+ Only SMB2 uses the IRQ and it has been documented as
+ being broken on real hardware. Most notably the status
+ bar scrolls with the rest of the screen and the game
+ completely crashes between the "our princess" scene of
+ world 4-4 and the beginning of world 5-1. How the IRQ
+ functions is to be confirmed but it likely uses a 12-bit
+ counter just like the other SMB2 bootlegs.  That is how
+ we presently emulate it here.
 
  NES 2.0: mapper 304
 
- In MAME: Partially supported. Need to emulate IRQ
- (needed by smb2 conversion?)
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
-void nes_09034a_device::write_ex(offs_t offset, uint8_t data)
+void nes_09034a_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
+{
+	if (id == TIMER_IRQ)
+	{
+		if (m_irq_enable)
+		{
+			m_irq_count = (m_irq_count + 1) & 0x0fff;
+			if (!m_irq_count)
+				set_irq_line(ASSERT_LINE);
+		}
+	}
+}
+
+void nes_09034a_device::write_ex(offs_t offset, u8 data)
 {
 	LOG_MMC(("09-034a write_ex, offset: %04x, data: %02x\n", offset, data));
 
-	if (offset == 7)    // $4027
-		m_reg = data & 1;
+	offset += 0x20;
+	switch (offset)
+	{
+		case 0x0027:
+			m_reg = data & 1;
+			break;
+		case 0x0068:
+			m_irq_enable = BIT(data, 0);
+			if (!m_irq_enable)
+			{
+				m_irq_count = 0;
+				set_irq_line(CLEAR_LINE);
+			}
+			break;
+	}
 }
 
-uint8_t nes_09034a_device::read_m(offs_t offset)
+u8 nes_09034a_device::read_ex(offs_t offset)
+{
+	LOG_MMC(("09-034a read_ex, offset: %04x, data: %02x\n", offset));
+
+	offset += 0x20;
+	// SMB2 does not boot with the default open bus reads in this range
+	if (offset >= 0x42 && offset <= 0x55)
+		return 0xff;
+	else
+		return get_open_bus();
+}
+
+u8 nes_09034a_device::read_m(offs_t offset)
 {
 	LOG_MMC(("09-034a read_m, offset: %04x\n", offset));
 	// in 0x6000-0x7fff is mapped the 2nd PRG chip which starts after 32K (hence the +4)
-	return m_prg[((m_reg + 4) * 0x2000) + offset];
+	return m_prg[(((m_reg + 4) * 0x2000) + offset) & (m_prg_size - 1)];
 }
 
 /*-------------------------------------------------

src/devices/bus/nes/bootleg.h

@@ -260,19 +260,26 @@ class nes_09034a_device : public nes_nrom_device
 {
 public:
 	// construction/destruction
-	nes_09034a_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
+	nes_09034a_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
 
-	virtual void write_ex(offs_t offset, uint8_t data) override;
-	virtual uint8_t read_m(offs_t offset) override;
+	virtual void write_ex(offs_t offset, u8 data) override;
+	virtual u8 read_ex(offs_t offset) override;
+	virtual u8 read_m(offs_t offset) override;
 
 	virtual void pcb_reset() override;
 
 protected:
 	// device-level overrides
 	virtual void device_start() override;
+	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) override;
 
 private:
-	uint8_t m_reg;
+	u16 m_irq_count;
+	int m_irq_enable;
+	u8 m_reg;
+
+	static const device_timer_id TIMER_IRQ = 0;
+	emu_timer *irq_timer;
 };
 
 

src/mame/machine/nes.cpp

@@ -83,13 +83,13 @@ void nes_state::machine_start()
 			space.install_read_handler(0x8000, 0xffff, read8sm_delegate(*m_cartslot, FUNC(nes_cart_slot_device::read_h)));
 		}
 
-		if (m_cartslot->get_pcb_id() == BTL_SMB2JB || m_cartslot->get_pcb_id() == UNL_AC08 || m_cartslot->get_pcb_id() == UNL_SMB2J || m_cartslot->get_pcb_id() == BTL_09034A)
+		if (m_cartslot->get_pcb_id() == BTL_SMB2JB || m_cartslot->get_pcb_id() == UNL_AC08 || m_cartslot->get_pcb_id() == UNL_SMB2J)
 		{
 			logerror("write_ex installed!\n");
 			space.install_write_handler(0x4020, 0x40ff, write8sm_delegate(*m_cartslot, FUNC(nes_cart_slot_device::write_ex)));
 		}
 
-		if (m_cartslot->get_pcb_id() == KAISER_KS7017 || m_cartslot->get_pcb_id() == UNL_603_5052 || m_cartslot->get_pcb_id() == STD_DISKSYS)
+		if (m_cartslot->get_pcb_id() == BTL_09034A || m_cartslot->get_pcb_id() == KAISER_KS7017 || m_cartslot->get_pcb_id() == UNL_603_5052 || m_cartslot->get_pcb_id() == STD_DISKSYS)
 		{
 			logerror("write_ex & read_ex installed!\n");
 			space.install_read_handler(0x4020, 0x40ff, read8sm_delegate(*m_cartslot, FUNC(nes_cart_slot_device::read_ex)));