/* Pythagorean addition using doubles

   Copyright (C) 2011-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library

   Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Library General Public License as

   published by the Free Software Foundation; either version 2 of the

   License, or (at your option) any later version.

   The GNU C Library 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

   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If

   not, see <http://www.gnu.org/licenses/>.  */

#include <math.h>

#include <math_private.h>

#include <math-underflow.h>

#include <stdint.h>

static const double two60   = 1.152921504606847e+18;

static const double two500  = 3.2733906078961419e+150;

static const double two600  = 4.149515568880993e+180;

static const double two1022 = 4.49423283715579e+307;

static const double twoM500 = 3.054936363499605e-151;

static const double twoM600 = 2.4099198651028841e-181;

static const double two60factor = 1.5592502418239997e+290;

static const double pdnum   = 2.225073858507201e-308;

/* __ieee754_hypot(x,y)

 *

 * This a FP only version without any FP->INT conversion.

 * It is similar to default C version, making appropriates

 * overflow and underflows checks as well scaling when it

 * is needed.

 */

#ifdef _ARCH_PWR7

/* POWER7 isinf and isnan optimization are fast. */

# define TEST_INF_NAN(x, y)                                       \

   if ((isinf(x) || isinf(y))					  \

       && !issignaling (x) && !issignaling (y))			  \

       return INFINITY;                                           \

   if (isnan(x) || isnan(y))                                      \

       return x + y;

# else

/* For POWER6 and below isinf/isnan triggers LHS and PLT calls are

 * costly (especially for POWER6). */

# define GET_TW0_HIGH_WORD(d1,d2,i1,i2)                           \

 do {                                                             \

   ieee_double_shape_type gh_u1;                                  \

   ieee_double_shape_type gh_u2;                                  \

   gh_u1.value = (d1);                                            \

   gh_u2.value = (d2);                                            \

   (i1) = gh_u1.parts.msw & 0x7fffffff;                           \

   (i2) = gh_u2.parts.msw & 0x7fffffff;                           \

 } while (0)

# define TEST_INF_NAN(x, y)                                      \

 do {                                                            \

   uint32_t hx, hy;                                              \

   GET_TW0_HIGH_WORD(x, y, hx, hy);                              \

   if (hy > hx) {                                                \

     uint32_t ht = hx; hx = hy; hy = ht;                         \

   }                                                             \

   if (hx >= 0x7ff00000) {                                       \

     if ((hx == 0x7ff00000 || hy == 0x7ff00000)			 \

	 && !issignaling (x) && !issignaling (y))		 \

       return INFINITY;                                          \

     return x + y;						 \

   }                                                             \

 } while (0)

#endif

double

__ieee754_hypot (double x, double y)

{

  x = fabs (x);

  y = fabs (y);

  TEST_INF_NAN (x, y);

  if (y > x)

    {

      double t = x;

      x = y;

      y = t;

    }

  if (y == 0.0)

    return x;

  /* if y is higher enough, y * 2^60 might overflow. The tests if

     y >= 1.7976931348623157e+308/2^60 (two60factor) and uses the

     appropriate check to avoid the overflow exception generation.  */

  if (y > two60factor)

    {

      if ((x / y) > two60)

	return x + y;

    }

  else

    {

      if (x > (y * two60))

	return x + y;

    }

  if (x > two500)

    {

      x *= twoM600;

      y *= twoM600;

      return sqrt (x * x + y * y) / twoM600;

    }

  if (y < twoM500)

    {

      if (y <= pdnum)

	{

	  x *= two1022;

	  y *= two1022;

	  double ret = sqrt (x * x + y * y) / two1022;

	  math_check_force_underflow_nonneg (ret);

	  return ret;

	}

      else

	{

	  x *= two600;

	  y *= two600;

	  return sqrt (x * x + y * y) / two600;

	}

    }

  return sqrt (x * x + y * y);

}

strong_alias (__ieee754_hypot, __hypot_finite)