/*

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

 * 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.

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

 */

/*

 * scalbn (double x, int n)

 * scalbn(x,n) returns x* 2**n  computed by  exponent

 * manipulation rather than by actually performing an

 * exponentiation or a multiplication.

 */

#include <math.h>

#include <math_private.h>

static const double

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

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

  huge = 1.0e+300,

  tiny = 1.0e-300;

double

__scalbn (double x, int n)

{

  int32_t k, hx, lx;

  EXTRACT_WORDS (hx, lx, x);

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

  if (__glibc_unlikely (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 (__glibc_unlikely (k == 0x7ff))

    return x + x;                                       /* NaN or Inf */

  if (__glibc_unlikely (n < -50000))

    return tiny * __copysign (tiny, x);   /*underflow*/

  if (__glibc_unlikely (n > 50000 || k + n > 0x7fe))

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

  /* Now k and n are bounded we know that k = k+n does not

     overflow.  */

  k = k + n;

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

    {

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

    }

  if (k <= -54)

    return tiny * __copysign (tiny, x);         /*underflow*/

  k += 54;                                      /* subnormal result */

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

  return x * twom54;

}

#ifdef NO_LONG_DOUBLE

strong_alias (__scalbn, __scalbnl)

#endif