libm/k_standardl.c

   1 /* Implement __kernel_standard_l.
   2    Copyright (C) 2012-2016 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.
  18
  19    Parts based on k_standard.c from fdlibm: */
  20
  21 /* @(#)k_standard.c 5.1 93/09/24 */
  22 /*
  23  * ====================================================
  24  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  25  *
  26  * Developed at SunPro, a Sun Microsystems, Inc. business.
  27  * Permission to use, copy, modify, and distribute this
  28  * software is freely granted, provided that this notice
  29  * is preserved.
  30  * ====================================================
  31  */
  32
  33 #include <math.h>
  34 #include "math_private.h"
  35 #include <fenv.h>
  36 #include <float.h>
  37 #include <errno.h>
  38
  39
  40 static double zero = 0.0;
  41
  42 /* Handle errors for a libm function as specified by TYPE (see
  43    comments in k_standard.c for details), with arguments X and Y,
  44    returning the appropriate return value for that function.  */
  45
  46 long double
  47 __kernel_standard_l (long double x, long double y, int type)
  48 {
  49   double dx, dy;
  50   struct exception exc;
  51   fenv_t env;
  52
  53   feholdexcept (&env);
  54   dx = x;
  55   dy = y;
  56   math_force_eval (dx);
  57   math_force_eval (dy);
  58   fesetenv (&env);
  59
  60   switch (type)
  61     {
  62     case 221:
  63       /* powl (x, y) overflow.  */
  64       exc.arg1 = dx;
  65       exc.arg2 = dy;
  66       exc.type = OVERFLOW;
  67       exc.name = (char *) "powl";
  68       if (_LIB_VERSION == _SVID_)
  69         {
  70           exc.retval = HUGE;
  71           y *= 0.5;
  72           if (x < zero && rint (y) != y)
  73             exc.retval = -HUGE;
  74         }
  75       else
  76         {
  77           exc.retval = HUGE_VAL;
  78           y *= 0.5;
  79           if (x < zero && rint (y) != y)
  80             exc.retval = -HUGE_VAL;
  81         }
  82       if (_LIB_VERSION == _POSIX_)
  83         __set_errno (ERANGE);
  84       else if (!matherr (&exc))
  85         __set_errno (ERANGE);
  86       return exc.retval;
  87
  88     case 222:
  89       /* powl (x, y) underflow.  */
  90       exc.arg1 = dx;
  91       exc.arg2 = dy;
  92       exc.type = UNDERFLOW;
  93       exc.name = (char *) "powl";
  94       exc.retval = zero;
  95       y *= 0.5;
  96       if (x < zero && rint (y) != y)
  97         exc.retval = -zero;
  98       if (_LIB_VERSION == _POSIX_)
  99         __set_errno (ERANGE);
 100       else if (!matherr (&exc))
 101         __set_errno (ERANGE);
 102       return exc.retval;
 103
 104     default:
 105       return __kernel_standard (dx, dy, type);
 106     }
 107 }