/*

 * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_RUNTIME_SHAREDRUNTIMEMATH_HPP

#define SHARE_RUNTIME_SHAREDRUNTIMEMATH_HPP

#include <math.h>

// Used to access the lower/higher 32 bits of a double

typedef union {

    double d;

    struct {

#ifdef VM_LITTLE_ENDIAN

      int lo;

      int hi;

#else

      int hi;

      int lo;

#endif

    } split;

} DoubleIntConv;

static inline int high(double d) {

  DoubleIntConv x;

  x.d = d;

  return x.split.hi;

}

static inline int low(double d) {

  DoubleIntConv x;

  x.d = d;

  return x.split.lo;

}

static inline void set_high(double* d, int high) {

  DoubleIntConv conv;

  conv.d = *d;

  conv.split.hi = high;

  *d = conv.d;

}

static inline void set_low(double* d, int low) {

  DoubleIntConv conv;

  conv.d = *d;

  conv.split.lo = low;

  *d = conv.d;

}

static double copysignA(double x, double y) {

  DoubleIntConv convX;

  convX.d = x;

  convX.split.hi = (convX.split.hi & 0x7fffffff) | (high(y) & 0x80000000);

  return convX.d;

}

/*

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

 * Copyright (c) 1998 Oracle and/or its affiliates. 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.

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

 */

/*

 * 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.

 */

static const double

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

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

hugeX  = 1.0e+300,

tiny   = 1.0e-300;

static double scalbnA(double x, int n) {

  int  k,hx,lx;

  hx = high(x);

  lx = low(x);

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

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

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

    x *= two54;

    hx = high(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 hugeX*copysignA(hugeX,x); /* overflow  */

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

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

    return x;

  }

  if (k <= -54) {

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

      return hugeX*copysignA(hugeX,x);  /*overflow*/

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

  }

  k += 54;                              /* subnormal result */

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

  return x*twom54;

}

#endif // SHARE_RUNTIME_SHAREDRUNTIMEMATH_HPP