+++ /dev/null
-/* SCTP kernel reference Implementation
- * Copyright (c) 1999-2000 Cisco, Inc.
- * Copyright (c) 1999-2001 Motorola, Inc.
- * Copyright (c) 2003 International Business Machines, Corp.
- *
- * This file is part of the SCTP kernel reference Implementation
- *
- * This file has direct heritage from the SCTP user-level reference
- * implementation by R. Stewart, et al. These functions implement the
- * Adler-32 algorithm as specified by RFC 2960.
- *
- * The SCTP reference implementation is free software;
- * you can redistribute it and/or modify it under the terms of
- * the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * The SCTP reference implementation is distributed in the hope that it
- * will be useful, but WITHOUT ANY WARRANTY; without even the implied
- * ************************
- * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GNU CC; see the file COPYING. If not, write to
- * the Free Software Foundation, 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- *
- * Please send any bug reports or fixes you make to the
- * email address(es):
- * lksctp developers <lksctp-developers@lists.sourceforge.net>
- *
- * Or submit a bug report through the following website:
- * http://www.sf.net/projects/lksctp
- *
- * Written or modified by:
- * Randall Stewart <rstewar1@email.mot.com>
- * Ken Morneau <kmorneau@cisco.com>
- * Qiaobing Xie <qxie1@email.mot.com>
- * Sridhar Samudrala <sri@us.ibm.com>
- *
- * Any bugs reported given to us we will try to fix... any fixes shared will
- * be incorporated into the next SCTP release.
- */
-
-/* This is an entry point for external calls
- * Define this function in the header file. This is
- * direct from rfc1950, ...
- *
- * The following C code computes the Adler-32 checksum of a data buffer.
- * It is written for clarity, not for speed. The sample code is in the
- * ANSI C programming language. Non C users may find it easier to read
- * with these hints:
- *
- * & Bitwise AND operator.
- * >> Bitwise right shift operator. When applied to an
- * unsigned quantity, as here, right shift inserts zero bit(s)
- * at the left.
- * << Bitwise left shift operator. Left shift inserts zero
- * bit(s) at the right.
- * ++ "n++" increments the variable n.
- * % modulo operator: a % b is the remainder of a divided by b.
- *
- * Well, the above is a bit of a lie, I have optimized this a small
- * tad, but I have commented the original lines below
- */
-
-#include <linux/types.h>
-#include <net/sctp/sctp.h>
-
-#define BASE 65521 /* largest prime smaller than 65536 */
-
-
-/* Performance work as shown this pig to be the
- * worst CPU wise guy. I have done what I could think
- * of on my flight to Australia but I am sure some
- * clever assembly could speed this up, but of
- * course this would require the dreaded #ifdef's for
- * architecture. If you can speed this up more, pass
- * it back and we will incorporate it :-)
- */
-
-unsigned long update_adler32(unsigned long adler,
- unsigned char *buf, int len)
-{
- __u32 s1 = adler & 0xffff;
- __u32 s2 = (adler >> 16) & 0xffff;
- int n;
-
- for (n = 0; n < len; n++,buf++) {
- /* s1 = (s1 + buf[n]) % BASE */
- /* first we add */
- s1 = (s1 + *buf);
-
- /* Now if we need to, we do a mod by
- * subtracting. It seems a bit faster
- * since I really will only ever do
- * one subtract at the MOST, since buf[n]
- * is a max of 255.
- */
- if (s1 >= BASE)
- s1 -= BASE;
-
- /* s2 = (s2 + s1) % BASE */
- /* first we add */
- s2 = (s2 + s1);
-
- /* again, it is more efficient (it seems) to
- * subtract since the most s2 will ever be
- * is (BASE-1 + BASE-1) in the worse case.
- * This would then be (2 * BASE) - 2, which
- * will still only do one subtract. On Intel
- * this is much better to do this way and
- * avoid the divide. Have not -pg'd on
- * sparc.
- */
- if (s2 >= BASE) {
- /* s2 %= BASE;*/
- s2 -= BASE;
- }
- }
-
- /* Return the adler32 of the bytes buf[0..len-1] */
- return (s2 << 16) + s1;
-}
-
-__u32 sctp_start_cksum(__u8 *ptr, __u16 count)
-{
- /*
- * Update a running Adler-32 checksum with the bytes
- * buf[0..len-1] and return the updated checksum. The Adler-32
- * checksum should be initialized to 1.
- */
- __u32 adler = 1L;
- __u32 zero = 0L;
-
- /* Calculate the CRC up to the checksum field. */
- adler = update_adler32(adler, ptr,
- sizeof(struct sctphdr) - sizeof(__u32));
- /* Skip over the checksum field. */
- adler = update_adler32(adler, (unsigned char *) &zero,
- sizeof(__u32));
- ptr += sizeof(struct sctphdr);
- count -= sizeof(struct sctphdr);
-
- /* Calculate the rest of the Adler-32. */
- adler = update_adler32(adler, ptr, count);
-
- return adler;
-}
-
-__u32 sctp_update_cksum(__u8 *ptr, __u16 count, __u32 adler)
-{
- adler = update_adler32(adler, ptr, count);
-
- return adler;
-}
-
-__u32 sctp_update_copy_cksum(__u8 *to, __u8 *from, __u16 count, __u32 adler)
-{
- /* Its not worth it to try harder. Adler32 is obsolescent. */
- adler = update_adler32(adler, from, count);
- memcpy(to, from, count);
-
- return adler;
-}
-
-__u32 sctp_end_cksum(__u32 adler)
-{
- return adler;
-}
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