From: Toni Wilen <twilen@winuae.net>
Date: Fri, 22 Aug 2025 16:13:44 +0000 (+0300)
Subject: WORDSYNC interrupt is inhibited if DSKLEN write bit is set.
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=bc78b11e7500969911767b48df6d494bf491e30b;p=francis%2Fwinuae.git

WORDSYNC interrupt is inhibited if DSKLEN write bit is set.
---

diff --git a/disk.cpp b/disk.cpp
index 2608d577..a8afdd31 100644
--- a/disk.cpp
+++ b/disk.cpp
@@ -4287,10 +4287,15 @@ static int doreaddma(void)
 
 static void wordsync_detected(bool startup)
 {
+	// wordsync interrupt is edge triggered
 	if (!dsksync_on) {
-		INTREQ_INT(12, 0);
+		// wordsync interrupt is inhibited if DSKLEN write bit is set
+		if (!(dsklen & 0x4000)) {
+			INTREQ_INT(12, 0);
+		}
 		dsksync_on = true;
 	}
+	// wordsync enables disk read if DMA is already active
 	if (dskdmaen != DSKDMA_OFF) {
 		int prev_dma_enabled = dma_enable;
 		if (!startup) {
@@ -4316,6 +4321,7 @@ static void wordsync_detected(bool startup)
 				dumpdisk(_T("SYNC"));
 		}
 	}
+	// wordsync match resets read shifter
 	if (adkcon & 0x0400) { // WORDSYNC
 		bitoffset = 15;
 	}
@@ -4849,9 +4855,6 @@ static void DSKLEN_2(uae_u16 v, int hpos)
 	dsklen2 = dsklen = v;
 	dsklength2 = dsklength = dsklen & 0x3fff;
 
-	if ((v & 0x8000) && !(prevlen & 0x8000)) {
-		//bitoffset = 15;
-	}
 	if ((v & 0x8000) && (prevlen & 0x8000)) {
 		if (dskdmaen == DSKDMA_READ && !(v & 0x4000)) {
 			// update only currently active DMA length, don't change DMA state
@@ -5140,16 +5143,8 @@ void DSKLEN(uae_u16 v, int hpos)
 	DISK_update_predict();
 }
 
-void DISK_update_adkcon (int hpos, uae_u16 v)
+void DISK_update_adkcon(int hpos, uae_u16 v)
 {
-	uae_u16 vold = adkcon;
-	uae_u16 vnew = adkcon;
-	if (v & 0x8000)
-		 vnew |= v & 0x7FFF;
-	else
-		vnew &= ~v;
-	if ((vnew & 0x400) && !(vold & 0x400))
-		bitoffset = 0;
 }
 
 void DSKSYNC(int hpos, uae_u16 v)