Refactored FIFO:s using new template based fifo class

src/devices/machine/z80dart.cpp

@@ -37,15 +37,17 @@
 //  MACROS / CONSTANTS
 //**************************************************************************
 
-#define VERBOSE 0
+#define VERBOSE 2
+#define LOGPRINT(x) do { if (VERBOSE) logerror x; } while (0)
+#define LOG(x)      {} LOGPRINT(x)
 
-#define LOG(x) do { if (VERBOSE) logerror x; } while (0)
+#if VERBOSE == 2
+#define logerror printf
+#endif
 
 #define CHANA_TAG   "cha"
 #define CHANB_TAG   "chb"
 
-
-
 //**************************************************************************
 //  DEVICE DEFINITIONS
 //**************************************************************************
@@ -503,7 +505,7 @@ z80dart_channel::z80dart_channel(const machine_config &mconfig, const char *tag,
 	: device_t(mconfig, Z80DART_CHANNEL, "Z80 DART channel", tag, owner, clock, "z80dart_channel", __FILE__),
 		device_serial_interface(mconfig, *this),
 		m_rx_error(0),
-		m_rx_fifo(-1),
+	  //		m_rx_fifo(-1),
 		m_rx_clock(0),
 		m_rx_first(0),
 		m_rx_break(0),
@@ -523,12 +525,13 @@ z80dart_channel::z80dart_channel(const machine_config &mconfig, const char *tag,
 
 	for (auto & elem : m_wr)
 		elem = 0;
-
+#if 0
 	for (int i = 0; i < 3; i++)
 	{
 		m_rx_data_fifo[i] = 0;
 		m_rx_error_fifo[i] = 0;
 	}
+#endif
 }
 
 
@@ -544,10 +547,15 @@ void z80dart_channel::device_start()
 	// state saving
 	save_item(NAME(m_rr));
 	save_item(NAME(m_wr));
+#if 0
 	save_item(NAME(m_rx_data_fifo));
 	save_item(NAME(m_rx_error_fifo));
-	save_item(NAME(m_rx_error));
 	save_item(NAME(m_rx_fifo));
+	save_item(NAME(m_rx_error));
+#else
+	//	save_item(NAME(m_rx_data_fifot));
+	//	save_item(NAME(m_rx_error_fifot));
+#endif
 	save_item(NAME(m_rx_clock));
 	save_item(NAME(m_rx_first));
 	save_item(NAME(m_rx_break));
@@ -1001,18 +1009,22 @@ uint8_t z80dart_channel::data_read()
 {
 	uint8_t data = 0;
 
-	if (m_rx_fifo >= 0)
+//	if (m_rx_fifo >= 0)
+	if (!m_rx_data_fifot.empty())
 	{
 		// load data from the FIFO
-		data = m_rx_data_fifo[m_rx_fifo];
+//		data = m_rx_data_fifo[m_rx_fifo];
+		data = m_rx_data_fifot.dequeue();
 
 		// load error status from the FIFO
-		m_rr[1] = (m_rr[1] & ~(RR1_CRC_FRAMING_ERROR | RR1_RX_OVERRUN_ERROR | RR1_PARITY_ERROR)) | m_rx_error_fifo[m_rx_fifo];
+//		m_rr[1] = (m_rr[1] & ~(RR1_CRC_FRAMING_ERROR | RR1_RX_OVERRUN_ERROR | RR1_PARITY_ERROR)) | m_rx_error_fifo[m_rx_fifo];
+		m_rr[1] = (m_rr[1] & ~(RR1_CRC_FRAMING_ERROR | RR1_RX_OVERRUN_ERROR | RR1_PARITY_ERROR)) | m_rx_error_fifot.dequeue();
 
 		// decrease FIFO pointer
-		m_rx_fifo--;
+//		m_rx_fifo--;
 
-		if (m_rx_fifo < 0)
+//		if (m_rx_fifo < 0)
+		if (m_rx_data_fifot.empty())
 		{
 			// no more characters available in the FIFO
 			m_rr[0] &= ~ RR0_RX_CHAR_AVAILABLE;
@@ -1064,7 +1076,8 @@ void z80dart_channel::receive_data(uint8_t data)
 {
 	LOG(("Z80DART \"%s\" Channel %c : Receive Data Byte '%02x'\n", m_owner->tag(), 'A' + m_index, data));
 
-	if (m_rx_fifo == 2)
+//	if (m_rx_fifo == 2)
+	if (m_rx_data_fifot.full())
 	{
 		// receive overrun error detected
 		m_rx_error |= RR1_RX_OVERRUN_ERROR;
@@ -1083,15 +1096,19 @@ void z80dart_channel::receive_data(uint8_t data)
 			m_uart->trigger_interrupt(m_index, INT_SPECIAL);
 			break;
 		}
+		m_rx_data_fifot.poke(data);
+		m_rx_error_fifot.poke(m_rx_error);
 	}
 	else
 	{
-		m_rx_fifo++;
+//		m_rx_fifo++;
+		m_rx_data_fifot.enqueue(data);
+		m_rx_error_fifot.enqueue(m_rx_error);
 	}
 
 // store received character and error status into FIFO
-	m_rx_data_fifo[m_rx_fifo] = data;
+//	m_rx_data_fifo[m_rx_fifo] = data;
-	m_rx_error_fifo[m_rx_fifo] = m_rx_error;
+//	m_rx_error_fifo[m_rx_fifo] = m_rx_error;
 
 	m_rr[0] |= RR0_RX_CHAR_AVAILABLE;
 

src/devices/machine/z80dart.h

@@ -241,6 +241,61 @@
 
 // ======================> z80dart_channel
 
+template <typename T, int N>
+class fifo
+{
+	T m_arr[N];
+	int m_wp;
+	int m_rp;
+	bool m_empty;
+public:
+	fifo()
+		: m_arr()
+		, m_wp(0)
+		, m_rp(0)
+		, m_empty(true)
+	{
+		static_assert(0U < N, "FIFO must have at least one element");
+	}
+
+	bool full() const { return !m_empty && (m_wp == m_rp); }
+	bool empty() const { return m_empty; }
+
+	void enqueue(T v)
+	{
+		if (m_empty || (m_wp != m_rp))
+		{
+			m_arr[m_wp] = v;
+			if (++m_wp == N) 
+				m_wp = 0;
+			m_empty = false;
+		}
+	}
+
+	T dequeue()
+	{
+		T result = -1;
+		if (!m_empty)
+		{
+			result = m_arr[m_rp];
+			if (++m_rp == N)
+				m_rp = 0;
+			m_empty = (m_rp == m_wp);
+		}
+		return result;
+	}
+
+	T const peek() const
+	{
+		return m_arr[m_rp];
+	}
+
+	void poke(T v)
+	{
+		m_arr[m_wp] = v;
+	}
+};
+
 class z80dart_device;
 
 class z80dart_channel : public device_t,
@@ -428,11 +483,15 @@ protected:
 	int get_tx_word_length();
 
 	// receiver state
+//#if 0
 	uint8_t m_rx_data_fifo[3];    // receive data FIFO
 	uint8_t m_rx_error_fifo[3];   // receive error FIFO
-	uint8_t m_rx_error;           // current receive error
 	int m_rx_fifo;              // receive FIFO pointer
-
+//#else
+	fifo<uint8_t, 3> m_rx_data_fifot;
+	fifo<uint8_t, 3> m_rx_error_fifot;
+//#endif
+	uint8_t m_rx_error;           // current receive error
 	int m_rx_clock;             // receive clock pulse count
 	int m_rx_first;             // first character received
 	int m_rx_break;             // receive break condition