--- ray/src/common/tonemap.c	1997/12/01 09:52:00	3.7
+++ ray/src/common/tonemap.c	1998/08/17 17:58:47	3.8
@@ -1,7 +1,7 @@
-/* Copyright (c) 1997 Regents of the University of California */
+/* Copyright (c) 1998 Silicon Graphics, Inc. */
 
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static char SCCSid[] = "$SunId$ SGI";
 #endif
 
 /*
@@ -186,7 +186,7 @@ int	len;
 
 	if (tmTop == NULL)
 		returnErr(TM_E_TMINVAL);
-	if (ls == NULL | scan == NULL | len <= 0)
+	if (ls == NULL | scan == NULL | len < 0)
 		returnErr(TM_E_ILLEGAL);
 	for (i = len; i--; ) {
 		if (tmNeedMatrix(tmTop))		/* get monitor RGB */
@@ -257,10 +257,12 @@ int	wt;
 	int	oldorig, oldlen, horig, hlen;
 	register int	i, j;
 
-	if (len <= 0)
-		returnErr(TM_E_ILLEGAL);
 	if (tmTop == NULL)
 		returnErr(TM_E_TMINVAL);
+	if (len < 0)
+		returnErr(TM_E_ILLEGAL);
+	if (len == 0)
+		returnOK;
 						/* first, grow limits */
 	if (tmTop->histo == NULL) {
 		for (i = len; i-- && ls[i] < MINBRT; )
@@ -448,7 +450,7 @@ int	len;
 
 	if (tmTop == NULL || tmTop->lumap == NULL)
 		returnErr(TM_E_TMINVAL);
-	if (ps == NULL | ls == NULL | len <= 0)
+	if (ps == NULL | ls == NULL | len < 0)
 		returnErr(TM_E_ILLEGAL);
 	while (len--) {
 		if ((li = *ls++) < tmTop->mbrmin)