From b5d2baccd4cd0076be4a883a11bc0d5423f104a1 Mon Sep 17 00:00:00 2001
From: Ben Campbell <ben@scumways.com>
Date: Wed, 6 Dec 2023 20:19:03 +1300
Subject: [PATCH] Generate Start Of Frame (SOF) interrupts.

---
 emulator/include/hardware.h     |  1 -
 emulator/src/hardware.cpp       | 23 ++++++++++++++++++++---
 emulator/src/hw_8042.cpp.unused |  8 --------
 emulator/src/hw_fifo.cpp        | 14 --------------
 4 files changed, 20 insertions(+), 26 deletions(-)

diff --git a/emulator/include/hardware.h b/emulator/include/hardware.h
index b17ecd2..412d483 100644
--- a/emulator/include/hardware.h
+++ b/emulator/include/hardware.h
@@ -28,6 +28,5 @@ BYTE8 HWReadKeyboardHardware(WORD16 address);
 void HWWriteKeyboardHardware(WORD16 address,BYTE8 data);
 void HWResetKeyboardHardware(void);
 void HWKeyboardHardwareDequeue(int key);
-int HWCheckKeyboardInterruptEnabled(void);
 
 #endif
\ No newline at end of file
diff --git a/emulator/src/hardware.cpp b/emulator/src/hardware.cpp
index d19e4f5..06aa5f6 100644
--- a/emulator/src/hardware.cpp
+++ b/emulator/src/hardware.cpp
@@ -118,9 +118,12 @@ void HWSync(void) {
 		int key = HWQueueRemove(&keyboardQueue);
 		HWKeyboardHardwareDequeue(key);
 		//printf("Dequeue %x\n",key);
-		if (HWCheckKeyboardInterruptEnabled()) {
-			//printf("Interrupt\n");
-			CPUInterruptMaskable();							// fire IRQ
+		// Trigger a kbd interrupt (if it's not masked).
+		if ((IOReadMemory(0,0xD66C) & 0x04) == 0) {
+			// mark it pending
+			BYTE8 pending = IOReadMemory(0, 0xD660);
+			pending |= 0x04;
+			IOWriteMemory(0, 0xD660, pending);
 		}
 	}
 	if (IOReadMemory(0,0xD658) & 1) { 						// Timer on.
@@ -133,6 +136,20 @@ void HWSync(void) {
 			a++;
 		}
 	}
+
+	// Trigger an SOF interrupt (if it's not masked).
+	if ((IOReadMemory(0,0xD66C) & 0x01) == 0) {
+		// mark it pending
+		BYTE8 pending = IOReadMemory(0, 0xD660);
+		pending |= 0x01;
+		IOWriteMemory(0, 0xD660, pending);
+	}
+
+	// if there are any interrupts pending, tell the CPU to run the handler.
+	if (IOReadMemory(0, 0xD660) != 0) {
+		CPUInterruptMaskable();
+	}
+
 }
 
 // *******************************************************************************************************************************
diff --git a/emulator/src/hw_8042.cpp.unused b/emulator/src/hw_8042.cpp.unused
index 95e38bf..4255260 100644
--- a/emulator/src/hw_8042.cpp.unused
+++ b/emulator/src/hw_8042.cpp.unused
@@ -57,11 +57,3 @@ void HWWriteKeyboardHardware(WORD16 address,BYTE8 data) {
 		if (data == 0x60) {} // TODO: Enable interrupt ?
 	}
 }
-
-int HWCheckKeyboardInterruptEnabled(void) {
-	if ((IOReadMemory(0,0xD66C) & 0x04) == 0) {			// Bit masked zero ?
-		IOWriteMemory(0,0xD660,4); 						// Set Pending Reg Bit 2
-		return -1;
-	}
-	return 0;
-}
\ No newline at end of file
diff --git a/emulator/src/hw_fifo.cpp b/emulator/src/hw_fifo.cpp
index 8d5c01e..76ebe28 100644
--- a/emulator/src/hw_fifo.cpp
+++ b/emulator/src/hw_fifo.cpp
@@ -75,17 +75,3 @@ BYTE8 HWReadKeyboardHardware(WORD16 address) {
 void HWWriteKeyboardHardware(WORD16 address,BYTE8 data) {
 	// Should clear the queue here. Not really required ?
 }
-
-// *******************************************************************************************************************************
-//
-//										Interrupt for new key enabled ?
-//
-// *******************************************************************************************************************************
-
-int HWCheckKeyboardInterruptEnabled(void) {
-	if ((IOReadMemory(0,0xD66C) & 0x04) == 0) {			// Bit masked zero ?
-		IOWriteMemory(0,0xD660,4); 						// Set Pending Reg Bit 2
-		return -1;
-	}
-	return 0;
-}
\ No newline at end of file