Further attempts to improve accuracy of 40105 emulation (nw)

src/devices/machine/40105.cpp

@@ -32,7 +32,7 @@
 //**************************************************************************
 
 const device_type CD40105 = &device_creator<cmos_40105_device>;
-
+const device_type HC40105 = &device_creator<cmos_40105_device>;
 
 
 //**************************************************************************
@@ -115,6 +115,54 @@ void cmos_40105_device::write(u8 data)
 	m_d = data & 0x0f;
 }
 
+WRITE8_MEMBER(cmos_40105_device::write)
+{
+	write(data);
+}
+
+
+//-------------------------------------------------
+//  load_input - load new data into FIFO
+//-------------------------------------------------
+
+void cmos_40105_device::load_input()
+{
+	if (m_fifo.size() == 16)
+	{
+		logerror("Attempt to load data into full FIFO\n");
+		return;
+	}
+
+	m_fifo.push(m_d);
+
+	// DIR remains low if FIFO is full, or else briefly pulses low
+	m_write_dir(0);
+	if (m_fifo.size() == 16)
+		m_dir = false;
+	else
+		m_write_dir(1);
+}
+
+
+//-------------------------------------------------
+//  output_ready - place new data at output
+//-------------------------------------------------
+
+void cmos_40105_device::output_ready()
+{
+	if (m_fifo.size() == 0)
+	{
+		logerror("Attempt to output data from empty FIFO\n");
+		return;
+	}
+
+	m_q = m_fifo.front();
+	m_write_q(m_q);
+
+	m_dor = true;
+	m_write_dor(1);
+}
+
 
 //-------------------------------------------------
 //  si_w - shift in write
@@ -122,24 +170,16 @@ void cmos_40105_device::write(u8 data)
 
 WRITE_LINE_MEMBER( cmos_40105_device::si_w )
 {
-	// activate on rising edge when ready
+	// load input on rising edge when ready
 	if (m_dir && !m_si && state)
 	{
-		m_fifo.push(m_d);
-
-		// DIR remains low if FIFO is full, or else briefly pulses low
-		m_write_dir(0);
-		if (m_fifo.size() == 16)
-			m_dir = false;
-		else
-			m_write_dir(1);
-
-		// signal availability of propagated data
+		load_input();
+	}
+	else if (m_si && !state && m_fifo.size() > 0)
+	{
+		// data propagates through FIFO when SI goes low
 		if (!m_dor)
-		{
-			m_dor = true;
-			m_write_dor(1);
-		}
+			output_ready();
 	}
 
 	m_si = state;
@@ -152,25 +192,26 @@ WRITE_LINE_MEMBER( cmos_40105_device::si_w )
 
 WRITE_LINE_MEMBER( cmos_40105_device::so_w )
 {
-	// activate on falling edge when ready
+	// shift out on falling edge when ready
 	if (m_dor && m_so && !state)
 	{
-		m_q = m_fifo.front();
 		m_fifo.pop();
+		m_dor = false;
 		m_write_dor(0);
-		m_write_q(m_q);
 
 		// DOR remains low if FIFO is now empty, or else briefly pulses low
 		if (m_fifo.size() > 0)
-			m_write_dor(1);
-		else
-			m_dor = false;
+			output_ready();
 
-		// FIFO can no longer be full
 		if (!m_dir)
 		{
+			// raise DIR since FIFO is no longer full
 			m_dir = true;
 			m_write_dir(1);
+
+			// load new input immediately if SI is held high
+			if (m_si)
+				load_input();
 		}
 	}
 

src/devices/machine/40105.h

@@ -60,6 +60,7 @@ public:
 
 	u8 read();
 	void write(u8 data);
+	DECLARE_WRITE8_MEMBER(write);
 
 	DECLARE_WRITE_LINE_MEMBER( si_w );
 	DECLARE_WRITE_LINE_MEMBER( so_w );
@@ -73,6 +74,11 @@ protected:
 	virtual void device_reset() override;
 
 private:
+	// private helpers
+	void load_input();
+	void output_ready();
+
+	// callbacks
 	devcb_write_line m_write_dir;
 	devcb_write_line m_write_dor;
 	devcb_write8 m_write_q;
@@ -91,7 +97,7 @@ private:
 
 // device type definition
 extern const device_type CD40105;
-
+extern const device_type HC40105;
 
 
 #endif

src/mame/machine/cedar_magnet_sound.cpp

@@ -79,9 +79,9 @@ WRITE8_MEMBER(cedar_magnet_sound_device::adpcm_fifo_w)
 	// Z80 code first unpacks 8 bytes of ADPCM sample data into nibbles
 	// and, upon receiving interrupt vector E6, fills FIFO at once using OTIR
 	// 4-bit data is shifted out of the FIFO to the MSM5205 by another timer
-	m_fifo->si_w(0);
 	m_fifo->write(data & 0x0f); // only low nibble is used here
 	m_fifo->si_w(1);
+	m_fifo->si_w(0);
 }
 
 WRITE8_MEMBER(cedar_magnet_sound_device::ay0_porta_w)
@@ -194,7 +194,7 @@ static MACHINE_CONFIG_FRAGMENT( cedar_magnet_sound )
 	MCFG_AY8910_PORT_A_WRITE_CB(WRITE8(cedar_magnet_sound_device, ay1_porta_w))
 	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.5)
 
-	MCFG_DEVICE_ADD("fifo", CD40105, 0) // HCF40105BE at IC13
+	MCFG_DEVICE_ADD("fifo", HC40105, 0) // HCF40105BE at IC13
 	MCFG_40105_DATA_OUT_READY_CB(WRITELINE(cedar_magnet_sound_device, fifo_dor_w))
 	MCFG_40105_DATA_OUT_CB(DEVWRITELINE("adpcm", msm5205_device, data_w))