/*
 * Copyright (c) 2015 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * ip4/ip_checksum.c: ip/tcp/udp checksums
 *
 * Copyright (c) 2008 Eliot Dresselhaus
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <vnet/ip/ip.h>

ip_csum_t
ip_incremental_checksum (ip_csum_t sum, void * _data, uword n_bytes)
{
  uword data = pointer_to_uword (_data);
  ip_csum_t sum0, sum1;

  sum0 = 0;
  sum1 = sum;

  /* Align data pointer to 64 bits. */
#define _(t)					\
do {						\
  if (n_bytes >= sizeof (t)			\
      && sizeof (t) < sizeof (ip_csum_t)	\
      && (data % (2 * sizeof (t))) != 0)	\
    {						\
      sum0 += * uword_to_pointer (data, t *);	\
      data += sizeof (t);			\
      n_bytes -= sizeof (t);			\
    }						\
} while (0)

  _ (u8);
  _ (u16);
  if (BITS (ip_csum_t) > 32)
    _ (u32);

#undef _

 {
   ip_csum_t * d = uword_to_pointer (data, ip_csum_t *);

   while (n_bytes >= 2 * sizeof (d[0]))
     {
       sum0 = ip_csum_with_carry (sum0, d[0]);
       sum1 = ip_csum_with_carry (sum1, d[1]);
       d += 2;
       n_bytes -= 2 * sizeof (d[0]);
     }

   data = pointer_to_uword (d);
 }
   
#define _(t)								\
do {									\
  if (n_bytes >= sizeof (t) && sizeof (t) <= sizeof (ip_csum_t))	\
    {									\
      sum0 = ip_csum_with_carry (sum0, * uword_to_pointer (data, t *));	\
      data += sizeof (t);						\
      n_bytes -= sizeof (t);						\
    }									\
} while (0)

 if (BITS (ip_csum_t) > 32)
   _ (u64);
 _ (u32);
 _ (u16);
 _ (u8);

#undef _

 /* Combine even and odd sums. */
 sum0 = ip_csum_with_carry (sum0, sum1);

 return sum0;
}

ip_csum_t
ip_csum_and_memcpy (ip_csum_t sum, void * dst, void * src, uword n_bytes)
{
  uword n_left, n_left_odd;
  ip_csum_t * dst_even, * src_even;
  ip_csum_t sum0 = sum, sum1;

  dst_even = uword_to_pointer
    (pointer_to_uword (dst) &~ (sizeof (sum) - 1),
     ip_csum_t *);
  src_even = src;

  n_left = n_bytes;
  if ((n_left_odd = dst - (void *) dst_even))
    {
      u8 * d8 = dst, * s8 = src;
      uword i, n_copy_odd;

      n_copy_odd = clib_min (n_left, n_left_odd);

      for (i = 0; i < n_copy_odd; i++)
	d8[i] = s8[i];

      if (n_copy_odd != n_left_odd)
	return sum0;

      sum0 = ip_csum_with_carry (sum0, dst_even[0]);
      dst_even += 1;
      src_even = (void *) (src + n_copy_odd);
      n_left -= n_left_odd;
    }

  sum1 = 0;
  while (n_left >= 2 * sizeof (dst_even[0]))
    {
      ip_csum_t dst0, dst1;

      dst0 = clib_mem_unaligned (&src_even[0], ip_csum_t);
      dst1 = clib_mem_unaligned (&src_even[1], ip_csum_t);

      dst_even[0] = dst0;
      dst_even[1] = dst1;

      dst_even += 2;
      src_even += 2;
      n_left -= 2 * sizeof (dst_even[0]);

      sum0 = ip_csum_with_carry (sum0, dst0);
      sum1 = ip_csum_with_carry (sum1, dst1);
    }

  if (n_left >= 1 * sizeof (dst_even[0]))
    {
      ip_csum_t dst0;

      dst0 = clib_mem_unaligned (&src_even[0], ip_csum_t);

      dst_even[0] = dst0;

      dst_even += 1;
      src_even += 1;
      n_left -= 1 * sizeof (dst_even[0]);

      sum0 = ip_csum_with_carry (sum0, dst0);
    }

  if (n_left > 0)
    {
      u8 * d8 = dst, * s8 = src;
      uword i;
      for (i = 0; i < n_left; i++)
	d8[i] = s8[i];
    }

  return ip_csum_with_carry (sum0, sum1);
}