--- visbjp_orig/Vis.h	2009-07-29 11:40:40.000000000 +0200
+++ visbjp/Vis.h	2010-01-12 14:36:30.865639900 +0100
@@ -119,12 +119,17 @@
 
 
 #ifndef __alpha
-extern	HANDLE	my_mutex;
-#define	LOCK	WaitForSingleObject( my_mutex, INFINITE )
-#define	UNLOCK	ReleaseMutex( my_mutex )
+extern	HANDLE	read_mutex;
+extern	HANDLE	save_mutex;
+#define	READ_LOCK	WaitForSingleObject( read_mutex, INFINITE )
+#define	READ_UNLOCK	ReleaseMutex( read_mutex )
+#define	SAVE_LOCK	WaitForSingleObject( save_mutex, INFINITE )
+#define	SAVE_UNLOCK	ReleaseMutex( save_mutex )
 #else
-#define	LOCK
-#define	UNLOCK
+#define	READ_LOCK
+#define	READ_UNLOCK
+#define	SAVE_LOCK
+#define	SAVE_UNLOCK
 #endif
 
 
--- visbjp_orig/Vis.c	2009-07-30 09:59:14.000000000 +0200
+++ visbjp/Vis.c	2010-01-12 14:37:20.364526800 +0100
@@ -19,7 +19,9 @@
 int			leafon;		// the next leaf to be given to a thread to process
 
 #ifndef __alpha
-HANDLE my_mutex;
+HANDLE read_mutex;
+HANDLE save_mutex;
+HANDLE work_mutexes[MAX_THREADS];
 #endif
 
 byte			*vismap, *vismap_p, *vismap_end; // past visfile
@@ -467,6 +469,16 @@
 			return;
 	}
 
+#ifndef __alpha
+	// We wait for all threads to finish processing their current portal.
+	// This way we should guarantee that no portals are marked
+	// as being processed.
+	if( work_mutexes[0] != NULL )
+	{
+		WaitForMultipleObjects( numthreads, work_mutexes, TRUE, INFINITE );
+	}
+#endif
+
 	PrevTime = Time;
 
 	State.PercRate = PercRate;
@@ -536,6 +548,16 @@
 	SavingTime = I_FloatTime () - Time;
 	State.StateTime += SavingTime;
 //logprintf ("State save: %.2lf\n", SavingTime);
+
+#ifndef __alpha
+	if( work_mutexes[0] != NULL )
+	{
+		for( i = 0; i < numthreads; i++ )
+		{
+			ReleaseMutex( work_mutexes[i] );
+		}
+	}
+#endif
 }
 
 /*
@@ -676,7 +698,7 @@
 	portal_t	*p, *tp;
 	int		min;
 
-	LOCK;
+	READ_LOCK;
 
 	min = 99999;
 	p = NULL;
@@ -694,7 +716,7 @@
 	if (p)
 		p->status = stat_working;
 
-	UNLOCK;
+	READ_UNLOCK;
 
 	return p;
 }
@@ -711,6 +733,7 @@
 void *LeafThread (int thread)
 #endif
 {
+	HANDLE		work_mutex = (HANDLE)lpParam;
 	portal_t	*p;
 
 	TimeOffset = State.CalcTime;
@@ -719,9 +742,14 @@
 	{
 		do
 		{
+			WaitForSingleObject( work_mutex, INFINITE );
+
 			p = GetNextPortal ();
 			if (!p)
+			{
+				ReleaseMutex( work_mutex );
 				break;
+			}
 
 			ShowPercent (NULL, State.CurrPortal + 1, numportals * 2 );
 
@@ -733,7 +761,14 @@
 			if (verbose)
 				logprintf ("  can see:%5i\n", p->numcansee);
 
+			ReleaseMutex( work_mutex );
+
+			SAVE_LOCK;
+
 			SaveState (NULL, State.CurrPortal, false);
+
+			SAVE_UNLOCK;
+			
 		} while (1);
 	}
 
@@ -914,20 +949,29 @@
 	HANDLE	work_threads[MAX_THREADS];
 	int		i;
 
-	my_mutex = CreateMutex( NULL, FALSE, NULL );
+	read_mutex = CreateMutex( NULL, FALSE, NULL );
+	save_mutex = CreateMutex( NULL, FALSE, NULL );
 
 	ShowPercent ("Full", 0, 0);
 
 	for( i = 0 ; i < numthreads ; i++ )
 	{
-		work_threads[i] = CreateThread( NULL, 0, LeafThread, NULL, 0, (LPDWORD)&work_threads[i] );
+		work_mutexes[i] = CreateMutex( NULL, FALSE, NULL );
+		work_threads[i] = CreateThread( NULL, 0, LeafThread, work_mutexes[i], 0, (LPDWORD)&work_threads[i] );
 	}
 
 	WaitForMultipleObjects( numthreads, work_threads, TRUE, INFINITE );
 
 	ShowPercent (NULL, 100, 100);
 
-	ReleaseMutex( my_mutex );
+	CloseHandle( read_mutex );
+	CloseHandle( save_mutex );
+
+	for( i = 0; i < numthreads; i++ )
+	{
+		CloseHandle( work_mutexes[i] );
+		CloseHandle( work_threads[i] );
+	}
 }
 #else
 	LeafThread (0);
@@ -1306,6 +1350,10 @@
 	if (i != argc - 1)
 		PrintOptions ();
 
+#ifndef __alpha
+	memset( work_mutexes, 0, sizeof( work_mutexes ) );
+#endif
+
 	start = I_FloatTime ();
 
 	strcpy (source, argv[i]);