/*--------------------------------------------------------------------

 *© Portions copyright (c) 2005 Nokia Corporation.  All rights reserved.

 *--------------------------------------------------------------------

*/

/* @(#)s_scalbn.c 5.1 93/09/24 */

/* @(#)fdlibm.h 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.

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

 */

#include <sys/cdefs.h>

#ifndef __SYMBIAN32__

__FBSDID("$FreeBSD: src/lib/libc/gen/ldexp.c,v 1.1 2005/01/22 06:03:40 das Exp $");

#endif //__SYMBIAN32__

#include <sys/types.h>

#include <stdapis/machine/endian.h>

#include <math.h>

/* Bit fiddling routines copied from msun/src/math_private.h,v 1.15 */

#if BYTE_ORDER == BIG_ENDIAN

typedef union

{

  double value;

  struct

  {

    u_int32_t msw;

    u_int32_t lsw;

  } parts;

} ieee_double_shape_type;

#endif

#if BYTE_ORDER == LITTLE_ENDIAN

typedef union

{

  double value;

  struct

  {

    u_int32_t lsw;

    u_int32_t msw;

  } parts;

} ieee_double_shape_type;

#endif

/* Get two 32 bit ints from a double.  */

#define EXTRACT_WORDS(ix0,ix1,d)				\

do {								\

  ieee_double_shape_type ew_u;					\

  ew_u.value = (d);						\

  (ix0) = ew_u.parts.msw;					\

  (ix1) = ew_u.parts.lsw;					\

} while (0)

/* Get the more significant 32 bit int from a double.  */

#define GET_HIGH_WORD(i,d)					\

do {								\

  ieee_double_shape_type gh_u;					\

  gh_u.value = (d);						\

  (i) = gh_u.parts.msw;						\

} while (0)

/* Set the more significant 32 bits of a double from an int.  */

#define SET_HIGH_WORD(d,v)					\

do {								\

  ieee_double_shape_type sh_u;					\

  sh_u.value = (d);						\

  sh_u.parts.msw = (v);						\

  (d) = sh_u.value;						\

} while (0)

static const double

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

twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */

huge   = 1.0e+300,

tiny   = 1.0e-300;

static double

_copysign(double x, double y)

{

	u_int32_t hx,hy;

	GET_HIGH_WORD(hx,x);

	GET_HIGH_WORD(hy,y);

	SET_HIGH_WORD(x,(hx&0x7fffffff)|(hy&0x80000000));

	return x;

}

EXPORT_C double

ldexp(double x, int n)

{

	int32_t k,hx,lx;

	EXTRACT_WORDS(hx,lx,x);

        k = (hx&0x7ff00000)>>20;		/* extract exponent */

        if (k==0) {				/* 0 or subnormal x */

            if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */

	    x *= two54;

	    GET_HIGH_WORD(hx,x);

	    k = ((hx&0x7ff00000)>>20) - 54;

            if (n< -50000) return tiny*x; 	/*underflow*/

	    }

        if (k==0x7ff) return x+x;		/* NaN or Inf */

        k = k+n;

        if (k >  0x7fe) return huge*_copysign(huge,x); /* overflow  */

        if (k > 0) 				/* normal result */

	    {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}

        if (k <= -54) {

            if (n > 50000) 	/* in case integer overflow in n+k */

		return huge*_copysign(huge,x);	/*overflow*/

	    else return tiny*_copysign(tiny,x); 	/*underflow*/

	}

        k += 54;				/* subnormal result */

	SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));

        return x*twom54;

}