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/* @(#)s_frexp.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_frexp.c,v 1.9 1995/05/10 20:47:24 jtc Exp $";
#endif
/*
* for non-zero x
* x = frexp(arg,&exp);
* return a double fp quantity x such that 0.5 <= |x| <1.0
* and the corresponding binary exponent "exp". That is
* arg = x*2^exp.
* If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
* with *exp=0.
*/
#include <math.h>
#include <math_private.h>
#include <libm-alias-double.h>
static const double
two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
double
__frexp (double x, int *eptr)
{
int32_t hx, ix, lx;
EXTRACT_WORDS (hx, lx, x);
ix = 0x7fffffff & hx;
*eptr = 0;
if (ix >= 0x7ff00000 || ((ix | lx) == 0))
return x + x; /* 0,inf,nan */
if (ix < 0x00100000) /* subnormal */
{
x *= two54;
GET_HIGH_WORD (hx, x);
ix = hx & 0x7fffffff;
*eptr = -54;
}
*eptr += (ix >> 20) - 1022;
hx = (hx & 0x800fffff) | 0x3fe00000;
SET_HIGH_WORD (x, hx);
return x;
}
libm_alias_double (__frexp, frexp)
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