sysdeps/ieee754/flt-32/math_errf.c

   1 /* Single-precision math error handling.
   2    Copyright (C) 2017 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_config.h"
  20
  21 #if WANT_ERRNO
  22 # include <errno.h>
  23 /* NOINLINE reduces code size.  */
  24 NOINLINE static float
  25 with_errnof (float y, int e)
  26 {
  27   errno = e;
  28   return y;
  29 }
  30 #else
  31 # define with_errnof(x, e) (x)
  32 #endif
  33
  34 /* NOINLINE prevents fenv semantics breaking optimizations.  */
  35 NOINLINE static float
  36 xflowf (unsigned long sign, float y)
  37 {
  38   y = (sign ? -y : y) * y;
  39   return with_errnof (y, ERANGE);
  40 }
  41
  42 attribute_hidden float
  43 __math_uflowf (unsigned long sign)
  44 {
  45   return xflowf (sign, 0x1p-95f);
  46 }
  47
  48 #if WANT_ERRNO_UFLOW
  49 /* Underflows to zero in some non-nearest rounding mode, setting errno
  50    is valid even if the result is non-zero, but in the subnormal range.  */
  51 attribute_hidden float
  52 __math_may_uflowf (unsigned long sign)
  53 {
  54   return xflowf (sign, 0x1.4p-75f);
  55 }
  56 #endif
  57
  58 attribute_hidden float
  59 __math_oflowf (unsigned long sign)
  60 {
  61   return xflowf (sign, 0x1p97f);
  62 }
  63
  64 attribute_hidden float
  65 __math_divzerof (unsigned long sign)
  66 {
  67   float y = 0;
  68   return with_errnof ((sign ? -1 : 1) / y, ERANGE);
  69 }
  70
  71 attribute_hidden float
  72 __math_invalidf (float x)
  73 {
  74   float y = (x - x) / (x - x);
  75   return isnan (x) ? y : with_errnof (y, EDOM);
  76 }