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/* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */
/*
* 64-bit IEEE not-a-number routines.
* This is big/little-endian portable assuming that
* the 64-bit doubles and 64-bit integers have the
* same byte ordering.
*/
#include "plan9.h"
#include <assert.h>
#include "fmt.h"
#include "fmtdef.h"
static uvlong uvnan = ((uvlong)0x7FF00000<<32)|0x00000001;
static uvlong uvinf = ((uvlong)0x7FF00000<<32)|0x00000000;
static uvlong uvneginf = ((uvlong)0xFFF00000<<32)|0x00000000;
/* gcc sees through the obvious casts. */
static uvlong
d2u(double d)
{
union {
uvlong v;
double d;
} u;
assert(sizeof(u.d) == sizeof(u.v));
u.d = d;
return u.v;
}
static double
u2d(uvlong v)
{
union {
uvlong v;
double d;
} u;
assert(sizeof(u.d) == sizeof(u.v));
u.v = v;
return u.d;
}
double
__NaN(void)
{
return u2d(uvnan);
}
int
__isNaN(double d)
{
uvlong x;
x = d2u(d);
/* IEEE 754: exponent bits 0x7FF and non-zero mantissa */
return (x&uvinf) == uvinf && (x&~uvneginf) != 0;
}
double
__Inf(int sign)
{
return u2d(sign < 0 ? uvneginf : uvinf);
}
int
__isInf(double d, int sign)
{
uvlong x;
x = d2u(d);
if(sign == 0)
return x==uvinf || x==uvneginf;
else if(sign > 0)
return x==uvinf;
else
return x==uvneginf;
}
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