/* S_FREXP.C

 * 

 * Portions Copyright (c) 1993-2005 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 */

/* @(#)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.

 * ====================================================

 */

/*

FUNCTION

       <<frexp>>, <<frexpf>>---split floating-point number

INDEX

	frexp

INDEX

	frexpf

ANSI_SYNOPSIS

	#include <math.h>

        double frexp(double <[val]>, int *<[exp]>);

        float frexpf(float <[val]>, int *<[exp]>);

TRAD_SYNOPSIS

	#include <math.h>

        double frexp(<[val]>, <[exp]>)

        double <[val]>;

        int *<[exp]>;

        float frexpf(<[val]>, <[exp]>)

        float <[val]>;

        int *<[exp]>;

DESCRIPTION

	All non zero, normal numbers can be described as <[m]> * 2**<[p]>.

	<<frexp>> represents the double <[val]> as a mantissa <[m]>

	and a power of two <[p]>. The resulting mantissa will always

	be greater than or equal to <<0.5>>, and less than <<1.0>> (as

	long as <[val]> is nonzero). The power of two will be stored

	in <<*>><[exp]>. 

@ifinfo

<[m]> and <[p]> are calculated so that

<[val]> is <[m]> times <<2>> to the power <[p]>.

@end ifinfo

@tex

<[m]> and <[p]> are calculated so that

$ val = m \times 2^p $.

@end tex

<<frexpf>> is identical, other than taking and returning

floats rather than doubles.

RETURNS

<<frexp>> returns the mantissa <[m]>. If <[val]> is <<0>>, infinity,

or Nan, <<frexp>> will set <<*>><[exp]> to <<0>> and return <[val]>.

PORTABILITY

<<frexp>> is ANSI.

<<frexpf>> is an extension.

*/

/*

 * 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 "FDLIBM.H"

static const double

two54 =  1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */

/**

Get mantissa and exponent of floating-point value.

Calculates mantissa (a floating-point value between 0.5 and 1) 

and exponent (an integer value) where x is parameter x, 

mantissa is the value returned by the function and exponent

is set by the function at location pointed by eptr.

@return Mantissa.

@param x Floating point value 

@param eptr Location where to exponent will be received.

*/	

EXPORT_C double frexp(double x, int *eptr) __SOFTFP

{

	__int32_t hx, ix, lx;

	EXTRACT_WORDS(hx,lx,x);

	ix = 0x7fffffff&hx;

	*eptr = 0;

	if(ix>=0x7ff00000||((ix|lx)==0)) return 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;

}