added interrupt handling

src/emu/cpu/melps4/m58846.c

@@ -10,7 +10,7 @@
 */
 
 #include "m58846.h"
-#include "debugger.h"
+//#include "debugger.h"
 
 
 
@@ -50,6 +50,9 @@ offs_t m58846_device::disasm_disassemble(char *buffer, offs_t pc, const UINT8 *o
 void m58846_device::device_start()
 {
 	melps4_cpu_device::device_start();
+	
+	m_timer[0] = timer_alloc(0);
+	m_timer[1] = timer_alloc(1);
 }
 
 
@@ -61,6 +64,52 @@ void m58846_device::device_start()
 void m58846_device::device_reset()
 {
 	melps4_cpu_device::device_reset();
+	
+	// timer 1 runs continuously
+	reset_timer1();
+}
+
+
+
+//-------------------------------------------------
+//  timers
+//-------------------------------------------------
+
+void m58846_device::reset_timer1()
+{
+	// reset 7-bit prescaler
+	attotime base = attotime::from_ticks(6 * 128, unscaled_clock());
+	m_timer[0]->adjust(base);
+}
+
+void m58846_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
+{
+	switch (id)
+	{
+		// timer 1
+		case 0:
+			m_irqflag[1] = true;
+			m_possible_irq = true;
+			reset_timer1();
+			break;
+
+		// timer 2
+		case 1:
+			break;
+
+		default:
+			assert_always(FALSE, "Unknown id in m58846_device::device_timer");
+			break;
+	}
+}
+
+void m58846_device::write_v(UINT8 data)
+{
+	// d0: enable timer 1 irq
+	m_tmr_irq_enabled[0] = (data & 1) ? true : false;
+	m_possible_irq = true;
+	
+	m_v = data;
 }
 
 

src/emu/cpu/melps4/m58846.h

@@ -29,6 +29,13 @@ protected:
 
 	// device_disasm_interface overrides
 	virtual offs_t disasm_disassemble(char *buffer, offs_t pc, const UINT8 *oprom, const UINT8 *opram, UINT32 options);
+
+	// timers
+	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);
+	virtual void write_v(UINT8 data);
+	
+	emu_timer *m_timer[2];
+	void reset_timer1();
 };
 
 

src/emu/cpu/melps4/melps4.c

@@ -46,12 +46,15 @@ void melps4_cpu_device::state_string_export(const device_state_entry &entry, std
 	{
 		// obviously not from a single flags register, letters are made up
 		case STATE_GENFLAGS:
-			strprintf(str, "%c%c%c%c%c",
+			strprintf(str, "%c%c%c%c%c %c%c%c",
 				m_intp ? 'P':'p',
 				m_inte ? 'I':'i',
 				m_sm   ? 'S':'s',
 				m_cps  ? 'D':'d',
-				m_cy   ? 'C':'c'
+				m_cy   ? 'C':'c',
+				m_irqflag[0] ? 'X':'.', // exf
+				m_irqflag[1] ? '1':'.', // 1f
+				m_irqflag[2] ? '2':'.'  // 2f
 			);
 			break;
 
@@ -111,7 +114,11 @@ void melps4_cpu_device::device_start()
 	m_skip = false;
 	m_inte = 0;
 	m_intp = 1;
+	m_irqflag[0] = m_irqflag[1] = m_irqflag[2] = false;
+	m_tmr_irq_enabled[0] = m_tmr_irq_enabled[1] = false;
+	m_int_state = 0;
 	m_prohibit_irq = false;
+	m_possible_irq = false;
 
 	m_a = 0;
 	m_b = 0;
@@ -147,7 +154,11 @@ void melps4_cpu_device::device_start()
 	save_item(NAME(m_skip));
 	save_item(NAME(m_inte));
 	save_item(NAME(m_intp));
+	save_item(NAME(m_irqflag));
+	save_item(NAME(m_tmr_irq_enabled));
+	save_item(NAME(m_int_state));
 	save_item(NAME(m_prohibit_irq));
+	save_item(NAME(m_possible_irq));
 
 	save_item(NAME(m_a));
 	save_item(NAME(m_b));
@@ -165,7 +176,7 @@ void melps4_cpu_device::device_start()
 
 	// register state for debugger
 	state_add(STATE_GENPC, "curpc", m_pc).formatstr("%04X").noshow();
-	state_add(STATE_GENFLAGS, "GENFLAGS", m_cy).formatstr("%5s").noshow();
+	state_add(STATE_GENFLAGS, "GENFLAGS", m_cy).formatstr("%9s").noshow();
 
 	state_add(MELPS4_PC, "PC", m_pc).formatstr("%04X");
 	state_add(MELPS4_A, "A", m_a).formatstr("%2d"); // show in decimal
@@ -194,17 +205,19 @@ void melps4_cpu_device::device_reset()
 {
 	m_sm = m_sms = false;
 	m_ba_flag = false;
-	m_prohibit_irq = false;
-	
 	m_skip = false;
 	m_op = m_prev_op = 0;
 	m_pc = m_prev_pc = 0;
-	m_inte = 0;
-	m_intp = 1;
 	op_lcps(); // CPS=0
 
-	m_v = 0;
+	// clear interrupts
-	m_w = 0;
+	m_inte = 0;
+	m_intp = 1;
+	write_v(0);
+	write_w(0);
+	m_irqflag[0] = m_irqflag[1] = m_irqflag[2] = false;
+	m_prohibit_irq = false;
+	m_possible_irq = false;
 
 	// clear ports
 	write_d_pin(MELPS4_PORTD_CLR, 0);
@@ -291,6 +304,73 @@ void melps4_cpu_device::write_d_pin(int bit, int state)
 
 
 
+//-------------------------------------------------
+//  interrupts
+//-------------------------------------------------
+
+void melps4_cpu_device::execute_set_input(int line, int state)
+{
+	state = (state) ? 1 : 0;
+	
+	switch (line)
+	{
+		// external interrupt
+		case MELPS4_INPUT_LINE_INT:
+			// irq on rising/falling edge
+			if (state != m_int_state && state == m_intp)
+			{
+				m_irqflag[0] = true;
+				m_possible_irq = true;
+			}
+			m_int_state = state;
+			break;
+		
+		// timer input pin
+		case MELPS4_INPUT_LINE_T:
+			break;
+
+		default:
+			break;
+	}
+}
+
+void melps4_cpu_device::do_interrupt(int which)
+{
+	m_inte = 0;
+	m_irqflag[which] = false;
+	
+	m_icount--;
+	push_pc();
+	m_sms = m_sm;
+	m_sm = false;
+	m_op = 0; // fake nop
+	m_pc = m_int_page << 7 | (which * 2);
+	
+	standard_irq_callback(which);
+}
+
+void melps4_cpu_device::check_interrupt()
+{
+	if (!m_inte)
+		return;
+
+	int which = 0;
+	
+	// assume that lower irq vectors have higher priority
+	if (m_irqflag[0])
+		which = 0;
+	else if (m_irqflag[1] && m_tmr_irq_enabled[0])
+		which = 1;
+	else if (m_irqflag[2] && m_tmr_irq_enabled[1])
+		which = 2;
+	else
+		return;
+	
+	do_interrupt(which);
+}
+
+
+
 //-------------------------------------------------
 //  execute
 //-------------------------------------------------
@@ -314,8 +394,14 @@ void melps4_cpu_device::execute_run()
 		m_prev_op = m_op;
 		m_prev_pc = m_pc;
 		
-		// irq is not accepted during skip or LXY, LA, EI, DI, RT/RTS/RTI or any branch
+		// Interrupts are not accepted during skips or LXY, LA, EI, DI, RT/RTS/RTI or any branch.
-		//..
+		// Documentation is conflicting here: older docs say that it is allowed during skips,
+		// newer docs specifically say when interrupts are prohibited.
+		if (m_possible_irq && !m_prohibit_irq && !m_skip)
+		{
+			m_possible_irq = false;
+			check_interrupt();
+		}
 		m_prohibit_irq = false;
 
 		// fetch next opcode

src/emu/cpu/melps4/melps4.h

@@ -60,6 +60,12 @@ enum
 	MELPS4_PORTU
 };
 
+enum
+{
+	MELPS4_INPUT_LINE_INT = 0,
+	MELPS4_INPUT_LINE_T
+};
+
 
 
 // pinout reference
@@ -142,8 +148,9 @@ protected:
 	virtual UINT64 execute_clocks_to_cycles(UINT64 clocks) const { return (clocks + 6 - 1) / 6; } // 6 t-states per machine cycle
 	virtual UINT64 execute_cycles_to_clocks(UINT64 cycles) const { return (cycles * 6); } // "
 	virtual UINT32 execute_min_cycles() const { return 1; }
-	virtual UINT32 execute_max_cycles() const { return 1; }
+	virtual UINT32 execute_max_cycles() const { return 1+1; } // max opcode cycles + interrupt duration
 	virtual UINT32 execute_input_lines() const { return 3; } // up to 3 (some internal)
+	virtual void execute_set_input(int line, int state);
 	virtual void execute_run();
 	virtual void execute_one();
 
@@ -189,14 +196,18 @@ protected:
 	UINT8 m_port_s;         // "
 	UINT8 m_port_f;         // "
 
-	bool m_sm, m_sms;       // subroutine mode flag + stack
+	bool m_sm, m_sms;       // subroutine mode flag + irq stack
 	bool m_ba_flag;         // temp flag indicates BA opcode was executed
 	UINT8 m_sp_param;       // temp register holding SP opcode parameter
 	UINT8 m_cps;            // DP,CY or DP',CY' selected
 	bool m_skip;            // skip next opcode
 	UINT8 m_inte;           // interrupt enable flag
-	UINT8 m_intp;           // external interrupt polarity ('40 to '44)
+	int m_intp;             // external interrupt polarity ('40 to '44)
+	bool m_irqflag[3];      // irq flags: exf, 1f, 2f (external, timer 1, timer 2)
+	bool m_tmr_irq_enabled[2];
+	int m_int_state;        // INT pin state
 	bool m_prohibit_irq;    // interrupt is prohibited during certain opcodes
+	bool m_possible_irq;    // indicate that irq needs to be rechecked
 
 	// work registers (unless specified, each is 4-bit)
 	UINT8 m_a;              // accumulator
@@ -226,6 +237,11 @@ protected:
 	devcb_write8 m_write_u;
 	devcb_write_line m_write_t;
 	
+	virtual void write_v(UINT8 data) { m_v = data; }
+	virtual void write_w(UINT8 data) { m_w = data; }
+	virtual void do_interrupt(int which);
+	virtual void check_interrupt();
+
 	UINT8 read_gen_port(int port);
 	void write_gen_port(int port, UINT8 data);
 	int read_d_pin(int bit);

src/emu/cpu/melps4/melps4op.inc

@@ -419,25 +419,27 @@ void melps4_cpu_device::op_tab2()
 void melps4_cpu_device::op_tva()
 {
 	// TVA: transfer A to timer control V
-	m_v = m_a;
+	write_v(m_a);
 }
 
 void melps4_cpu_device::op_twa()
 {
 	// TWA: transfer A to timer control W
-	m_w = m_a;
+	write_w(m_a);
 }
 
 void melps4_cpu_device::op_snz1()
 {
 	// SNZ1: skip next on flag 1F
-	op_illegal();
+	m_skip = m_irqflag[1];
+	m_irqflag[1] = false;
 }
 
 void melps4_cpu_device::op_snz2()
 {
 	// SNZ2: skip next on flag 2F
-	op_illegal();
+	m_skip = m_irqflag[2];
+	m_irqflag[2] = false;
 }
 
 
@@ -631,6 +633,7 @@ void melps4_cpu_device::op_ei()
 {
 	// EI: enable interrupt flag
 	m_prohibit_irq = true;
+	m_possible_irq = true;
 	m_inte = 1;
 }