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/* $Id: sequence.c 4871 2001-07-09 08:09:58Z alexk $
**
** Sequence space arithmetic routines.
**
** This is a set of routines for implementing so called sequence
** space arithmetic (typically used for DNS serial numbers). The
** implementation here is taken from RFC 1982.
*/
#include "config.h"
#include "clibrary.h"
#include <limits.h>
#include "inn/sequence.h"
/*
** compare two unsigned long numbers using sequence space arithmetic
**
** returns:
** 0 - i1 = i2
** -1 - i1 < i2
** 1 - i1 > i2
** INT_MAX - undefined
*/
int
seq_lcompare(unsigned long i1, unsigned long i2)
{
if (i1 == i2)
return 0;
else if ((i1 < i2 && i2 - i1 < (1 + ULONG_MAX / 2)) ||
(i1 > i2 && i1 - i2 > (1 + ULONG_MAX / 2)))
return -1;
else if ((i1 < i2 && i2 - i1 > (1 + ULONG_MAX / 2)) ||
(i1 > i2 && i1 - i2 < (1 + ULONG_MAX / 2)))
return 1;
return INT_MAX;
}
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