sysdeps/i386/fpu/bits/fenv.h

   1 /* Copyright (C) 1997, 1998, 1999, 2000, 2011 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #ifndef _FENV_H
  20 # error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
  21 #endif
  22
  23
  24 /* Define bits representing the exception.  We use the bit positions
  25    of the appropriate bits in the FPU control word.  */
  26 enum
  27   {
  28     FE_INVALID = 0x01,
  29 #define FE_INVALID      FE_INVALID
  30     __FE_DENORM = 0x02,
  31     FE_DIVBYZERO = 0x04,
  32 #define FE_DIVBYZERO    FE_DIVBYZERO
  33     FE_OVERFLOW = 0x08,
  34 #define FE_OVERFLOW     FE_OVERFLOW
  35     FE_UNDERFLOW = 0x10,
  36 #define FE_UNDERFLOW    FE_UNDERFLOW
  37     FE_INEXACT = 0x20
  38 #define FE_INEXACT      FE_INEXACT
  39   };
  40
  41 #define FE_ALL_EXCEPT \
  42         (FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
  43
  44 /* The ix87 FPU supports all of the four defined rounding modes.  We
  45    use again the bit positions in the FPU control word as the values
  46    for the appropriate macros.  */
  47 enum
  48   {
  49     FE_TONEAREST = 0,
  50 #define FE_TONEAREST    FE_TONEAREST
  51     FE_DOWNWARD = 0x400,
  52 #define FE_DOWNWARD     FE_DOWNWARD
  53     FE_UPWARD = 0x800,
  54 #define FE_UPWARD       FE_UPWARD
  55     FE_TOWARDZERO = 0xc00
  56 #define FE_TOWARDZERO   FE_TOWARDZERO
  57   };
  58
  59
  60 /* Type representing exception flags.  */
  61 typedef unsigned short int fexcept_t;
  62
  63
  64 /* Type representing floating-point environment.  This function corresponds
  65    to the layout of the block written by the `fstenv'.  */
  66 typedef struct
  67   {
  68     unsigned short int __control_word;
  69     unsigned short int __unused1;
  70     unsigned short int __status_word;
  71     unsigned short int __unused2;
  72     unsigned short int __tags;
  73     unsigned short int __unused3;
  74     unsigned int __eip;
  75     unsigned short int __cs_selector;
  76     unsigned int __opcode:11;
  77     unsigned int __unused4:5;
  78     unsigned int __data_offset;
  79     unsigned short int __data_selector;
  80     unsigned short int __unused5;
  81   }
  82 fenv_t;
  83
  84 /* If the default argument is used we use this value.  */
  85 #define FE_DFL_ENV      ((__const fenv_t *) -1)
  86
  87 #ifdef __USE_GNU
  88 /* Floating-point environment where none of the exception is masked.  */
  89 # define FE_NOMASK_ENV  ((__const fenv_t *) -2)
  90 #endif
  91
  92
  93 #ifdef __USE_EXTERN_INLINES
  94 __BEGIN_DECLS
  95
  96 /* Optimized versions.  */
  97 extern int __REDIRECT_NTH (__feraiseexcept_renamed, (int), feraiseexcept);
  98 __extern_inline int
  99 __NTH (feraiseexcept (int __excepts))
 100 {
 101   if (__builtin_constant_p (__excepts)
 102       && (__excepts & ~(FE_INVALID | FE_DIVBYZERO)) == 0)
 103     {
 104       if ((FE_INVALID & __excepts) != 0)
 105         {
 106           /* One example of a invalid operation is 0.0 / 0.0.  */
 107           float __f = 0.0;
 108
 109 # ifdef __SSE_MATH__
 110           __asm__ __volatile__ ("divss %0, %0 " : : "x" (__f));
 111 # else
 112           __asm__ __volatile__ ("fdiv %%st, %%st(0); fwait"
 113                                 : "=t" (__f) : "0" (__f));
 114 # endif
 115           (void) &__f;
 116         }
 117       if ((FE_DIVBYZERO & __excepts) != 0)
 118         {
 119           float __f = 1.0;
 120           float __g = 0.0;
 121
 122 # ifdef __SSE_MATH__
 123           __asm__ __volatile__ ("divss %1, %0" : : "x" (__f), "x" (__g));
 124 # else
 125           __asm__ __volatile__ ("fdivp %%st(1), %%st; fwait"
 126                                 : "=t" (__f) : "0" (__f), "u" (__g) : "st(1)");
 127 # endif
 128           (void) &__f;
 129         }
 130
 131       return 0;
 132     }
 133
 134   return __feraiseexcept_renamed (__excepts);
 135 }
 136
 137 __END_DECLS
 138 #endif