1 files changed, 94 insertions, 0 deletions
diff --git a/lib/libstand/in_cksum.c b/lib/libstand/in_cksum.c
new file mode 100644
index 0000000..e6051bf
--- /dev/null
+++ b/lib/libstand/in_cksum.c
@@ -0,0 +1,94 @@
+/*	$NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $	*/
+
+/*
+ * Copyright (c) 1992 Regents of the University of California.
+ * All rights reserved.
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp  (LBL)
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <machine/endian.h>
+
+#include "stand.h"
+
+/*
+ * Checksum routine for Internet Protocol family headers.
+ * This routine is very heavily used in the network
+ * code and should be modified for each CPU to be as fast as possible.
+ * In particular, it should not be this one.
+ */
+int
+in_cksum(p, len)
+	void *p;
+	int len;
+{
+	int sum = 0, oddbyte = 0, v = 0;
+	u_char *cp = p;
+
+	/* we assume < 2^16 bytes being summed */
+	while (len > 0) {
+		if (oddbyte) {
+			sum += v + *cp++;
+			len--;
+		}
+		if (((long)cp & 1) == 0) {
+			while ((len -= 2) >= 0) {
+				sum += *(u_short *)cp;
+				cp += 2;
+			}
+		} else {
+			while ((len -= 2) >= 0) {
+#if BYTE_ORDER == BIG_ENDIAN
+				sum += *cp++ << 8;
+				sum += *cp++;
+#else
+				sum += *cp++;
+				sum += *cp++ << 8;
+#endif
+			}
+		}
+		if ((oddbyte = len & 1) != 0)
+#if BYTE_ORDER == BIG_ENDIAN
+			v = *cp << 8;
+#else
+			v = *cp;
+#endif
+	}
+	if (oddbyte)
+		sum += v;
+	sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */
+	sum += sum >> 16;		/* add potential last carry */
+	return (0xffff & ~sum);
+}