--- ray/src/common/urand.c	1998/01/05 16:47:37	2.4
+++ ray/src/common/urand.c	2006/04/05 06:22:56	2.10
@@ -1,25 +1,26 @@
-/* Copyright (c) 1998 Silicon Graphics, Inc. */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ SGI";
+static const char	RCSid[] = "$Id: urand.c,v 2.10 2006/04/05 06:22:56 greg Exp $";
 #endif
-
 /*
  * Anticorrelated random function due to Christophe Schlick
  */
 
+#include "copyright.h"
+
+#include  <stdlib.h>
+
+#include  "standard.h"
 #include  "random.h"
 
-#define  NULL		0
+#undef initurand
 
 #define  MAXORDER	(8*sizeof(unsigned short))
 
-extern char  *malloc();
+static unsigned short  empty_tab = 0;
 
-unsigned short  *urperm = NULL;	/* urand() permutation */
-int  urmask;		/* bits used in permutation */
+unsigned short  *urperm = &empty_tab;	/* urand() permutation */
+int  urmask = 0;			/* bits used in permutation */
 
-
 int
 initurand(size)		/* initialize urand() for size entries */
 int  size;
@@ -27,13 +28,19 @@ int  size;
 	int  order, n;
 	register int  i, offset;
 
-	if (urperm != NULL)
-		free((char *)urperm);
-	size--;
-	for (i = 1; size >>= 1; i++)
-		;
-	order = i>MAXORDER ? MAXORDER : i;
-	urmask = (1<<i) - 1;
+	if ((urperm != NULL) & (urperm != &empty_tab))
+		free((void *)urperm);
+	if (--size <= 0) {
+		empty_tab = 0;
+		urperm = &empty_tab;
+		urmask = 0;
+		return(0);
+	}
+	for (i = 1; (size >>= 1); i++)
+		if (i == MAXORDER)
+			break;
+	order = i;
+	urmask = (1<<order) - 1;
 	urperm = (unsigned short *)malloc((urmask+1)*sizeof(unsigned short));
 	if (urperm == NULL) {
 		eputs("out of memory in initurand\n");
@@ -42,14 +49,13 @@ int  size;
 	urperm[0] = 0;
 	for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
 		for (i = offset; i--; ) {
-			urperm[i] =
-			urperm[i+offset] = 2*urperm[i];
+			urperm[i+offset] = urperm[i] <<= 1;
 			if (random() & 0x4000)
 				urperm[i]++;
 			else
 				urperm[i+offset]++;
 		}
-	return(1<<order);
+	return(urmask+1);
 }
 
 
@@ -58,11 +64,11 @@ ilhash(d, n)			/* hash a set of integer values */
 register int  *d;
 register int  n;
 {
-	static int  tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
+	static int  tab[8] = {103699,96289,73771,65203,81119,87037,92051,98899};
 	register int  hval;
 
 	hval = 0;
 	while (n-- > 0)
-		hval += *d++ * tab[n&7];
-	return(hval);
+		hval ^= *d++ * tab[n&7];
+	return(hval & 0x7fffffff);
 }