/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*           Copyright (c) 1996-2006 AT&T Knowledge Ventures            *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                      by AT&T Knowledge Ventures                      *
*                                                                      *
*                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

/*
 * att
 */

#define att_description	\
	"The system 5 release 4 checksum. This is the default for \bsum\b \
	when \bgetconf UNIVERSE\b is \batt\b. This is the only true sum; \
	all of the other methods are order dependent."
#define att_options	0
#define att_match	"att|sys5|s5|default"
#define att_open	long_open
#define att_init	long_init
#define att_print	long_print
#define att_data	long_data
#define att_scale	512

static int
att_block(register Sum_t* p, const void* s, size_t n)
{
	register unsigned _ast_int4_t	c = ((Integral_t*)p)->sum;
	register unsigned char*		b = (unsigned char*)s;
	register unsigned char*		e = b + n;

	while (b < e)
		c += *b++;
	((Integral_t*)p)->sum = c;
	return 0;
}

static int
att_done(Sum_t* p)
{
	register unsigned _ast_int4_t	c = ((Integral_t*)p)->sum;

	c = (c & 0xffff) + ((c >> 16) & 0xffff);
	c = (c & 0xffff) + (c >> 16);
	((Integral_t*)p)->sum = c & 0xffff;
	return short_done(p);
}
