From 5e4c0867b96951f33c0a10959759b21805a986bf Mon Sep 17 00:00:00 2001
From: steve <jscrane@gmail.com>
Date: Tue, 26 Sep 2023 17:01:04 +0100
Subject: [PATCH] implement irq_a1 and irq_b1

---
 io.cpp  | 27 +++------------------------
 io.h    |  2 --
 pia.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 pia.h   | 27 +++++++++++++++++++--------
 4 files changed, 68 insertions(+), 34 deletions(-)

diff --git a/io.cpp b/io.cpp
index 3ad6247..b36d605 100644
--- a/io.cpp
+++ b/io.cpp
@@ -84,8 +84,9 @@ void io::down(uint8_t scan) {
 }
 
 void io::enter(uint8_t key) {
+	PIA::write_ca1(false);
 	PIA::write_porta(key + 0x80);
-	PIA::write_porta_cr(0xa7);
+	PIA::write_ca1(true);
 }
 
 void io::up(uint8_t scan) {
@@ -146,36 +147,14 @@ void io::write_portb(uint8_t b) {
 	PIA::write_portb(b);
 }
 
-void io::write_portb_cr(uint8_t b) {
-	if (PIA::read_portb_cr() < 0x80)
-		PIA::write_portb_cr(b);
-}
-
 uint8_t io::read_porta_cr() {
-	uint8_t b = PIA::read_porta_cr();
-	if (b & 0x80) {
-		PIA::write_porta_cr(0);
-		b = 0xa7;
-	}
-	if (b != 0xa7)
-		return b;
-
 	if (_loading) {
 		if (files.more())
 			enter(files.read());
 		else
 			_loading = false;
 	}
-	return b;
-}
-
-void io::write_porta_cr(uint8_t b) {
-	uint8_t cr = PIA::read_porta_cr();
-	if (!(cr & 0x80) && b >= 0x80)
-		cr |= 0x80;
-	else
-		cr = b;
-	PIA::write_porta_cr(cr);
+	return PIA::read_porta_cr();
 }
 
 void io::checkpoint(Stream &s) {
diff --git a/io.h b/io.h
index 81743bb..e11a40e 100644
--- a/io.h
+++ b/io.h
@@ -16,9 +16,7 @@ public:
 	virtual void restore(Stream &);
 
 	virtual void write_portb(uint8_t);
-	virtual void write_portb_cr(uint8_t);
 	virtual uint8_t read_porta_cr();
-	virtual void write_porta_cr(uint8_t);
 
 	void load();
 	filer &files;
diff --git a/pia.cpp b/pia.cpp
index 62217ad..2d0b473 100644
--- a/pia.cpp
+++ b/pia.cpp
@@ -5,6 +5,10 @@
 // see: https://github.com/mamedev/mame/blob/master/src/devices/machine/6821pia.cpp
 // and: https://github.com/mamedev/mame/blob/master/src/devices/machine/6821pia.h
 
+inline bool c1_low_to_high(uint8_t cr) { return cr & 0x02; }
+
+inline bool c1_high_to_low(uint8_t cr) { return !c1_low_to_high(cr); }
+
 void PIA::write(Memory::address a, uint8_t b) {
 #if defined(DEBUGGING)
 	Serial.print(millis());
@@ -53,6 +57,10 @@ void PIA::checkpoint(Stream &s) {
 	s.write(portb);
 	s.write(porta_cr);
 	s.write(porta);
+	s.write(irq_b1);
+	s.write(irq_a1);
+	s.write(cb1);
+	s.write(ca1);
 }
 
 void PIA::restore(Stream &s) {
@@ -60,4 +68,42 @@ void PIA::restore(Stream &s) {
 	portb = s.read();
 	porta_cr = s.read();
 	porta = s.read();
+	irq_b1 = s.read();
+	irq_a1 = s.read();
+	cb1 = s.read();
+	ca1 = s.read();
+}
+
+void PIA::write_ca1(bool state) {
+
+	if (ca1 == state)
+		return;
+
+	if ((state && c1_low_to_high(porta_cr)) || (!state && c1_high_to_low(porta_cr)))
+		irq_a1 = true;
+
+	ca1 = state;
+}
+
+void PIA::write_cb1(bool state) {
+
+	if (cb1 == state)
+		return;
+
+	if ((state && c1_low_to_high(portb_cr)) || (!state && c1_high_to_low(portb_cr)))
+		irq_b1 = true;
+
+	cb1 = state;
+}
+
+uint8_t PIA::read_porta_cr() {
+	if (irq_a1)
+		return porta_cr | IRQ1;
+	return porta_cr;
+}
+
+uint8_t PIA::read_portb_cr() {
+	if (irq_b1)
+		return portb_cr | IRQ1;
+	return portb_cr;
 }
diff --git a/pia.h b/pia.h
index e07c275..efd30b8 100644
--- a/pia.h
+++ b/pia.h
@@ -4,8 +4,12 @@
 // https://en.wikipedia.org/wiki/Peripheral_Interface_Adapter
 class PIA {
 public:
-	PIA(): portb(0), portb_cr(0), porta(0), porta_cr(0) {}
-	virtual void reset() { portb = portb_cr = porta = porta_cr = 0; }
+	PIA(): portb(0), portb_cr(0), porta(0), porta_cr(0), irq_a1(false), irq_b1(false) {}
+
+	virtual void reset() {
+		portb = portb_cr = porta = porta_cr = 0;
+		irq_a1 = irq_b1 = ca1 = cb1 = false;
+	}
 
 	void write(Memory::address, uint8_t);
 	uint8_t read(Memory::address);
@@ -13,19 +17,26 @@ public:
 	void checkpoint(Stream &);
 	void restore(Stream &);
 
+	void write_ca1(bool);
+	void write_cb1(bool);
+
+	static const uint8_t IRQ1 = 0x80;
+
 protected:
 	// "device-side" operations (called from memory interface)
-	virtual uint8_t read_porta() { return porta; }
-	virtual uint8_t read_porta_cr() { return porta_cr; }
-	virtual uint8_t read_portb() { return portb; }
-	virtual uint8_t read_portb_cr() { return portb_cr; }
+	virtual uint8_t read_porta() { irq_a1 = false; return porta; }
+	virtual uint8_t read_porta_cr();
+	virtual uint8_t read_portb() { irq_b1 = false; return portb; }
+	virtual uint8_t read_portb_cr();
 
 	virtual void write_porta(uint8_t b) { porta = b; }
-	virtual void write_porta_cr(uint8_t b) { porta_cr = b; }
+	virtual void write_porta_cr(uint8_t b) { porta_cr = (b & 0x3f); }
 	virtual void write_portb(uint8_t b) { portb = b; }
-	virtual void write_portb_cr(uint8_t b) { portb_cr = b; }
+	virtual void write_portb_cr(uint8_t b) { portb_cr = (b & 0x3f); }
 
 private:
 	uint8_t portb_cr, portb, porta_cr, porta;
+	bool ca1, irq_a1;
+	bool cb1, irq_b1;
 };
 #endif