From 83cc46dae321701579fac7c57500111b37f97c95 Mon Sep 17 00:00:00 2001
From: Toni Wilen <twilen@winuae.net>
Date: Sun, 27 Nov 2022 13:45:17 +0200
Subject: [PATCH] Fix CIA-A TOD counting if CIA internal delays caused it to
 cross scanline.

---
 cia.cpp | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/cia.cpp b/cia.cpp
index a9169b63..5b7ba2b3 100644
--- a/cia.cpp
+++ b/cia.cpp
@@ -1046,8 +1046,9 @@ static void CIA_tod_inc(bool irq, int num)
 {
 	struct CIA *c = &cia[num];
 	c->tod_event_state = 3; // done
-	if (!c->todon)
+	if (!c->todon) {
 		return;
+	}
 	c->tod++;
 	c->tod &= 0xFFFFFF;
 	cia_checkalarm(true, irq, num);
@@ -1056,8 +1057,9 @@ static void CIA_tod_inc(bool irq, int num)
 static void CIA_tod_inc_event(uae_u32 num)
 {
 	struct CIA *c = &cia[num];
-	if (c->tod_event_state != 2)
+	if (c->tod_event_state != 2) {
 		return;
+	}
 	CIA_tod_inc(true, num);
 }
 
@@ -1093,12 +1095,18 @@ static void CIA_tod_check(int num)
 	event2_newevent_xx(-1, -hpos * CYCLE_UNIT, num, CIA_tod_inc_event);
 }
 
-static void CIA_tod_handler(int hoffset, int num)
+static void CIA_tod_handler(int hoffset, int num, bool delayedevent)
 {
 	struct CIA *c = &cia[num];
 	c->tod_event_state = 0;
 	c->tod_offset = tod_inc_delay(hoffset);
 	if (c->tod_offset >= maxhpos) {
+		if (!delayedevent) {
+			return;
+		}
+		// crossed scanline, increase in next line
+		c->tod_offset -= maxhpos;
+		c->tod_event_state = 4;
 		return;
 	}
 	c->tod_event_state = 1; // TOD inc needed
@@ -1118,11 +1126,11 @@ void CIAA_tod_handler(int hoffset)
 		return;
 	}
 #endif
-	CIA_tod_handler(hoffset, 0);
+	CIA_tod_handler(hoffset, 0, true);
 }
 void CIAB_tod_handler(int hoffset)
 {
-	CIA_tod_handler(hoffset, 1);
+	CIA_tod_handler(hoffset, 1, false);
 }
 
 void keyboard_connected(bool connect)
@@ -1171,8 +1179,9 @@ static void check_keyboard(void)
 static void cia_delayed_tod(int num)
 {
 	struct CIA *c = &cia[num];
-	if (c->tod_event_state == 1)
+	if (c->tod_event_state == 1) {
 		CIA_tod_inc(false, num);
+	}
 	c->tod_event_state = 0;
 	c->tod_offset = -1;
 }
@@ -1203,6 +1212,10 @@ void CIA_hsync_posthandler(bool ciahsync, bool dotod)
 
 	if (!ciahsync) {
 		// Increase CIA-A TOD if delayed from previous line
+		struct CIA *c = &cia[0];
+		if (c->tod_event_state == 4) {
+			c->tod_event_state = 1;
+		}
 		cia_delayed_tod(0);
 		if (currprefs.tod_hack && cia[0].todon) {
 			do_tod_hack();
-- 
2.47.3