/*
* The authors of this software are Rob Pike and Ken Thompson,
* with contributions from Mike Burrows and Sean Dorward.
*
* Copyright (c) 2002-2006 by Lucent Technologies.
* Portions Copyright (c) 2004 Google Inc.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose without fee is hereby granted, provided that this entire notice
* is included in all copies of any software which is or includes a copy
* or modification of this software and in all copies of the supporting
* documentation for such software.
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES
* NOR GOOGLE INC MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING
* THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
*/
/*
* 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 <u.h>
#include <libc.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;
}