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sum-bsd.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1996-2007 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * bsd
 */

#define bsd_description \
      "The BSD checksum."
#define bsd_options     0
#define bsd_match "bsd|ucb"
#define bsd_open  long_open
#define bsd_init  long_init
#define bsd_done  short_done
#define bsd_print long_print
#define bsd_data  long_data
#define bsd_scale 1024

static int
bsd_block(register Sum_t* p, const void* s, size_t n)
{
      register uint32_t c = ((Integral_t*)p)->sum;
      register unsigned char* b = (unsigned char*)s;
      register unsigned char* e = b + n;

      while (b < e)
            c = ((c >> 1) + *b++ + ((c & 01) ? 0x8000 : 0)) & 0xffff;
      ((Integral_t*)p)->sum = c;
      return 0;
}

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