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/*

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

 * 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

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

INDEX

	frexp

INDEX

	frexpf

	#include 

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

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

	#include 

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

        double <[val]>;

        int *<[exp]>;

        float <[val]>;

        int *<[exp]>;

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

	<> 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]>.

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

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

@end ifnottex

@tex

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

$ val = m \times 2^p $.

@end tex

floats rather than doubles.

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

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

<> is ANSI.

<> 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.

 */

static const double

#else

static double

#endif

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

	double frexp(double x, int *eptr)

#else

	double frexp(x, eptr)

	double x; int *eptr;

#endif

{

	__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;

}

>