sysdeps/ieee754/dbl-64/math_err.c

   1 /* Double-precision math error handling.
   2    Copyright (C) 2018-2023 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    <https://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 attribute_hidden double
  37 __math_edom (double y)
  38 {
  39   return with_errno (y, EDOM);
  40 }
  41
  42 /* NOINLINE reduces code size.  */
  43 NOINLINE static double
  44 xflow (uint32_t sign, double y)
  45 {
  46   y = math_opt_barrier (sign ? -y : y) * y;
  47   return with_errno (y, ERANGE);
  48 }
  49
  50 attribute_hidden double
  51 __math_uflow (uint32_t sign)
  52 {
  53   return xflow (sign, 0x1p-767);
  54 }
  55
  56 #if WANT_ERRNO_UFLOW
  57 /* Underflows to zero in some non-nearest rounding mode, setting errno
  58    is valid even if the result is non-zero, but in the subnormal range.  */
  59 attribute_hidden double
  60 __math_may_uflow (uint32_t sign)
  61 {
  62   return xflow (sign, 0x1.8p-538);
  63 }
  64 #endif
  65
  66 attribute_hidden double
  67 __math_oflow (uint32_t sign)
  68 {
  69   return xflow (sign, 0x1p769);
  70 }
  71
  72 attribute_hidden double
  73 __math_divzero (uint32_t sign)
  74 {
  75   double y = math_opt_barrier (sign ? -1.0 : 1.0) / 0.0;
  76   return with_errno (y, ERANGE);
  77 }
  78
  79 attribute_hidden double
  80 __math_invalid (double x)
  81 {
  82   double y = (x - x) / (x - x);
  83   return isnan (x) ? y : with_errno (y, EDOM);
  84 }
  85
  86 /* Check result and set errno if necessary.  */
  87
  88 attribute_hidden double
  89 __math_check_uflow (double y)
  90 {
  91   return y == 0.0 ? with_errno (y, ERANGE) : y;
  92 }
  93
  94 attribute_hidden double
  95 __math_check_oflow (double y)
  96 {
  97   return isinf (y) ? with_errno (y, ERANGE) : y;
  98 }