From f97b4bb8001f1e15031438cb8b562ec7f701a9a9 Mon Sep 17 00:00:00 2001
From: Sjoerd van der Berg <harekiet@users.sourceforge.net>
Date: Thu, 31 Jul 2003 16:05:16 +0000
Subject: [PATCH] BSR and BSF correctly set zero flag now and 0 source for scan

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@1176
---
 src/cpu/core_full/op.h | 68 +++++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 28 deletions(-)

diff --git a/src/cpu/core_full/op.h b/src/cpu/core_full/op.h
index 8243fdaf..99d90f3e 100644
--- a/src/cpu/core_full/op.h
+++ b/src/cpu/core_full/op.h
@@ -479,53 +479,65 @@ switch (inst.code.op) {
 	case O_BSFw:
 		{
 			FILLFLAGS;
-			if (!inst.op1.w) SETFLAGBIT(ZF,true);
-			Bitu count=0;
-			while (count<16) {
-				if ((inst.op1.w>>count) & 1) break;
-				count++;
+			if (!inst.op1.w) {
+				SETFLAGBIT(ZF,true);
+			} else {
+				Bitu count=0;
+				while (count<16) {
+					if ((inst.op1.w>>count) & 1) break;
+					count++;
+				}
+				inst.op1.d=count;
+				SETFLAGBIT(ZF,false);
 			}
-			inst.op1.d=count;
-			SETFLAGBIT(ZF,false);
 		}
 		break;
 	case O_BSFd:
 		{
 			FILLFLAGS;
-			if (!inst.op1.d) SETFLAGBIT(ZF,true);
-			Bitu count=0;
-			while (count<32) {
-				if ((inst.op1.d>>count) & 1) break;
-				count++;
+			if (!inst.op1.d) {
+				SETFLAGBIT(ZF,true);
+			} else {
+				Bitu count=0;
+				while (count<32) {
+					if ((inst.op1.d>>count) & 1) break;
+					count++;
+				}
+				inst.op1.d=count;
+				SETFLAGBIT(ZF,false);
 			}
-			inst.op1.d=count;
-			SETFLAGBIT(ZF,false);
 		}
 		break;
 	case O_BSRw:
 		{
 			FILLFLAGS;
-			if (!inst.op1.w) SETFLAGBIT(ZF,true);
-			Bits count=15;
-			while (count>0) {
-				if ((inst.op1.w>>count) & 1) break;
-				count--;
+			if (!inst.op1.w) {
+				SETFLAGBIT(ZF,true);
+			} else {
+				Bits count=15;
+				while (count>0) {
+					if ((inst.op1.w>>count) & 1) break;
+					count--;
+				}
+				inst.op1.d=count;
+				SETFLAGBIT(ZF,false);
 			}
-			inst.op1.d=count;
-			SETFLAGBIT(ZF,false);
 		}
 		break;
 	case O_BSRd:
 		{
 			FILLFLAGS;
-			if (!inst.op1.d) SETFLAGBIT(ZF,true);
-			Bits count=31;
-			while (count>0) {
-				if ((inst.op1.d>>count) & 1) break;
-				count--;
+			if (!inst.op1.d) {
+				SETFLAGBIT(ZF,true);
+			} else {
+				Bits count=31;
+				while (count>0) {
+					if ((inst.op1.d>>count) & 1) break;
+					count--;
+				}
+				inst.op1.d=count;
+				SETFLAGBIT(ZF,false);
 			}
-			inst.op1.d=count;
-			SETFLAGBIT(ZF,false);
 		}
 		break;
 	case O_BTw: