From: Toni Wilen <twilen@winuae.net>
Date: Fri, 9 Aug 2019 19:31:48 +0000 (+0300)
Subject: 68020/030 DIVU.W divide by zero flag fix. Same behavior as 68000.
X-Git-Tag: 4300~158
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=b275cd75896cdf644b1aa15f4db00cc2bc93bbe9;p=francis%2Fwinuae.git

68020/030 DIVU.W divide by zero flag fix. Same behavior as 68000.
---

diff --git a/newcpu_common.cpp b/newcpu_common.cpp
index 9784d5fd..c29c69c3 100644
--- a/newcpu_common.cpp
+++ b/newcpu_common.cpp
@@ -762,7 +762,7 @@ int getDivs68kCycles (uae_s32 dividend, uae_s16 divisor)
 /* DIV divide by zero
  *
  * 68000 Signed: NVC=0 Z=1. Unsigned: VC=0 N=(dst>>16)<0 Z=(dst>>16)==0
- * 68020 and 68030: Signed: Z=1 NVC=0. Unsigned: V=1, N<dst, Z=!N, C=0.
+ * 68020 and 68030: Signed: Z=1 NVC=0. Unsigned: V=1, N=(dst>>16)<0 Z=(dst>>16)==0, C=0.
  * 68040/68060 C=0.
  *
  */
@@ -770,13 +770,15 @@ void divbyzero_special (bool issigned, uae_s32 dst)
 {
 	if (currprefs.cpu_model == 68020 || currprefs.cpu_model == 68030) {
 		CLEAR_CZNV ();
-		if (issigned == false) {
-			if (dst < 0) 
-				SET_NFLG (1);
-			SET_ZFLG (!GET_NFLG ());
-			SET_VFLG (1);
+		if (issigned) {
+			SET_ZFLG(1);
 		} else {
-			SET_ZFLG (1);
+			uae_s16 d = dst >> 16;
+			if (d < 0)
+				SET_NFLG(1);
+			else if (d == 0)
+				SET_ZFLG(1);
+			SET_VFLG (1);
 		}
 	} else if (currprefs.cpu_model >= 68040) {
 		SET_CFLG (0);