/* SCTP kernel reference Implementation
   * Copyright (c) 1999-2001 Motorola, Inc.
   * Copyright (c) 2001-2003 International Business Machines, Corp.
   *
   * This file is part of the SCTP kernel reference Implementation
   *
   * SCTP Checksum functions
   *
   * 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, see
   * <http://www.gnu.org/licenses/>.
   *
   * Please send any bug reports or fixes you make to the
   * email address(es):
   *    lksctp developers <linux-sctp@vger.kernel.org>
   *
   * Written or modified by:
   *    Dinakaran Joseph
   *    Jon Grimm <jgrimm@us.ibm.com>
   *    Sridhar Samudrala <sri@us.ibm.com>
   *
   * Rewritten to use libcrc32c by:
   *    Vlad Yasevich <vladislav.yasevich@hp.com>
   */
  
  #ifndef __sctp_checksum_h__
  #define __sctp_checksum_h__
  
  #include <linux/types.h>
  #include <net/sctp/sctp.h>
  #include <linux/crc32c.h>
  #include <linux/crc32.h>
  
  static inline __wsum sctp_csum_update(const void *buff, int len, __wsum sum)
  {
  	/* This uses the crypto implementation of crc32c, which is either
  	 * implemented w/ hardware support or resolves to __crc32c_le().
  	 */
  	return crc32c(sum, buff, len);
  }
  
  static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
  				       int offset, int len)
  {
  	return __crc32c_le_combine(csum, csum2, len);
  }
  
  static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
  					unsigned int offset)
  {
  	struct sctphdr *sh = sctp_hdr(skb);
          __le32 ret, old = sh->checksum;
  	const struct skb_checksum_ops ops = {
  		.update  = sctp_csum_update,
  		.combine = sctp_csum_combine,
  	};
  
  	sh->checksum = 0;
  	ret = cpu_to_le32(~__skb_checksum(skb, offset, skb->len - offset,
  					  ~(__u32)0, &ops));
  	sh->checksum = old;
  
  	return ret;
  }
  
  #endif /* __sctp_checksum_h__ */