isinf.c
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/* public domain rewrite of isinf(3) */
#ifdef __osf__
#define _IEEE 1
#include <nan.h>
int
isinf(double n)
{
if (IsNANorINF(n) && IsINF(n)) {
return 1;
}
else {
return 0;
}
}
#else
#include "ruby/config.h"
#if defined(HAVE_FINITE) && defined(HAVE_ISNAN)
#include <math.h>
#ifdef HAVE_IEEEFP_H
#include <ieeefp.h>
#endif
/*
* isinf may be provided only as a macro.
* ex. HP-UX, Solaris 10
* http://www.gnu.org/software/automake/manual/autoconf/Function-Portability.html
*/
#ifndef isinf
int
isinf(double n)
{
return (!finite(n) && !isnan(n));
}
#endif
#else
#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
static double zero(void) { return 0.0; }
static double one (void) { return 1.0; }
static double inf (void) { return one() / zero(); }
int
isinf(double n)
{
static double pinf = 0.0;
static double ninf = 0.0;
if (pinf == 0.0) {
pinf = inf();
ninf = -pinf;
}
return memcmp(&n, &pinf, sizeof n) == 0
|| memcmp(&n, &ninf, sizeof n) == 0;
}
#endif
#endif