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s_frexp.c
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/
s_frexp.c
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/* @(#)s_frexp.c 1.4 95/01/18 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* 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.
*/
#ifndef __FDLIBM_H__
#include "fdlibm.h"
#endif
#ifndef __have_fpu_frexp
double __ieee754_frexp(double x, int *eptr)
{
int32_t hx, ix, lx;
static const double two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
GET_DOUBLE_WORDS(hx, lx, x);
ix = UC(0x7fffffff) & hx;
*eptr = 0;
if (ix >= IC(0x7ff00000) || ((ix | lx) == 0))
return x; /* 0,inf,nan */
if (ix < IC(0x00100000))
{ /* subnormal */
x *= two54;
GET_HIGH_WORD(hx, x);
ix = hx & UC(0x7fffffff);
*eptr = -54;
}
*eptr += (int)(ix >> 20) - 1022;
hx = (hx & UC(0x800fffff)) | UC(0x3fe00000);
SET_HIGH_WORD(x, hx);
return x;
}
#endif
double __frexp(double x, int *exp)
{
return __ieee754_frexp(x, exp);
}
__typeof(__frexp) frexp __attribute__((weak, alias("__frexp")));
#ifdef __NO_LONG_DOUBLE_MATH
long double __frexpl(long double x, int *expt) __attribute__((alias("__frexp")));
__typeof(__frexpl) frexpl __attribute__((weak, alias("__frexp")));
#endif