sysdeps/ieee754/dbl-64/math_err.c

   1 /* Double-precision math error handling.
   2    Copyright (C) 2018-2019 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 #include <math-barriers.h>
  20 #include "math_config.h"
  21
  22 #if WANT_ERRNO
  23 #include <errno.h>
  24 /* NOINLINE reduces code size and avoids making math functions non-leaf
  25    when the error handling is inlined.  */
  26 NOINLINE static double
  27 with_errno (double y, int e)
  28 {
  29   errno = e;
  30   return y;
  31 }
  32 #else
  33 #define with_errno(x, e) (x)
  34 #endif
  35
  36 /* NOINLINE reduces code size.  */
  37 NOINLINE static double
  38 xflow (uint32_t sign, double y)
  39 {
  40   y = math_opt_barrier (sign ? -y : y) * y;
  41   return with_errno (y, ERANGE);
  42 }
  43
  44 attribute_hidden double
  45 __math_uflow (uint32_t sign)
  46 {
  47   return xflow (sign, 0x1p-767);
  48 }
  49
  50 #if WANT_ERRNO_UFLOW
  51 /* Underflows to zero in some non-nearest rounding mode, setting errno
  52    is valid even if the result is non-zero, but in the subnormal range.  */
  53 attribute_hidden double
  54 __math_may_uflow (uint32_t sign)
  55 {
  56   return xflow (sign, 0x1.8p-538);
  57 }
  58 #endif
  59
  60 attribute_hidden double
  61 __math_oflow (uint32_t sign)
  62 {
  63   return xflow (sign, 0x1p769);
  64 }
  65
  66 attribute_hidden double
  67 __math_divzero (uint32_t sign)
  68 {
  69   double y = math_opt_barrier (sign ? -1.0 : 1.0) / 0.0;
  70   return with_errno (y, ERANGE);
  71 }
  72
  73 attribute_hidden double
  74 __math_invalid (double x)
  75 {
  76   double y = (x - x) / (x - x);
  77   return isnan (x) ? y : with_errno (y, EDOM);
  78 }
  79
  80 /* Check result and set errno if necessary.  */
  81
  82 attribute_hidden double
  83 __math_check_uflow (double y)
  84 {
  85   return y == 0.0 ? with_errno (y, ERANGE) : y;
  86 }
  87
  88 attribute_hidden double
  89 __math_check_oflow (double y)
  90 {
  91   return isinf (y) ? with_errno (y, ERANGE) : y;
  92 }