From abffe9b174e9d5c4d2bdf819d9c31432ed115884 Mon Sep 17 00:00:00 2001
From: Claudio Jeker <claudio@cvs.openbsd.org>
Date: Wed, 12 Oct 2005 10:13:31 +0000
Subject: Revert last commit. That file was not intended to be commited.

---
 usr.sbin/ospfd/iso_cksum.c | 38 ++++++++++++++------------------------
 1 file changed, 14 insertions(+), 24 deletions(-)

diff --git a/usr.sbin/ospfd/iso_cksum.c b/usr.sbin/ospfd/iso_cksum.c
index de8d2c6a156..7863539ce15 100644
--- a/usr.sbin/ospfd/iso_cksum.c
+++ b/usr.sbin/ospfd/iso_cksum.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: iso_cksum.c,v 1.2 2005/10/12 09:51:58 claudio Exp $ */
+/*	$OpenBSD: iso_cksum.c,v 1.3 2005/10/12 10:13:30 claudio Exp $ */
 
 /*
  * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
@@ -21,18 +21,17 @@
 #include "ospfd.h"
 #include "log.h"
 
-/* implementation of Fletcher Checksum -- see RFC 1008 for more info */
-
 /* pos needs to be 0 for verify and 2 <= pos < len for calculation */
 u_int16_t
 iso_cksum(void *buf, u_int16_t len, u_int16_t pos)
 {
 	u_int8_t	*p = buf;
-	int		 c0 = 0, c1 = 0, x;	/* counters */
+	int		 c0 = 0, c1 = 0;	/* counters */
+	int		 r0, r1;		/* results */
 	u_int16_t	 sop;
 
-	sop = len - pos - 1;	/* pos is an offset (pos 2 is 3rd element) */
-	p += 2;			/* jump over age field */
+	sop = len - pos - 1;	/* pos is an offset (pos 2 is at len 3) */
+	p += 2;
 	len -= 2;
 	while (len--) {
 		c0 += *p++;
@@ -42,27 +41,18 @@ iso_cksum(void *buf, u_int16_t len, u_int16_t pos)
 			c0 %= 255;
 			c1 %= 255;
 		}
-#ifdef DEBUG
-		if (c0 + 256 < c0 || c1 + 256 < c1)
-			fatalx("iso_cksum: overflowed");
-#endif
 	}
+	r0 = c0 = c0 % 255;
+	r1 = c1 % 255;
 
 	if (pos) {
-		x = ((sop * c0 - c1)) % 255;
-		if (x <= 0)
-			x += 255;
-#if 1
-		c1 = 510 - c0 - x;
-		if (c1 > 255)
-			c1 -= 255;
-#else
-		c1 = (-c0 - x) % 255;
-		if (c1 < 0)
-			c1 += 255;
-#endif
-		c0 = x;
+		r0 = ((sop * r0 - r1)) % 255;
+		if (r0 <= 0)
+			r0 += 255;
+		r1 = 510 - r0 - c0;
+		if (r1 > 255)
+			r1 -= 255;
 	}
 
-	return (c0 << 8 | c1);
+	return (r0 << 8 | r1);
 }
-- 
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