sysdeps/x86_64/fpu/bits/fenv.h

   1 /* Copyright (C) 1997-2012 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _FENV_H
  19 # error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
  20 #endif
  21
  22 /* Define bits representing the exception.  We use the bit positions
  23    of the appropriate bits in the FPU control word.  */
  24 enum
  25   {
  26     FE_INVALID = 0x01,
  27 #define FE_INVALID      FE_INVALID
  28     __FE_DENORM = 0x02,
  29     FE_DIVBYZERO = 0x04,
  30 #define FE_DIVBYZERO    FE_DIVBYZERO
  31     FE_OVERFLOW = 0x08,
  32 #define FE_OVERFLOW     FE_OVERFLOW
  33     FE_UNDERFLOW = 0x10,
  34 #define FE_UNDERFLOW    FE_UNDERFLOW
  35     FE_INEXACT = 0x20
  36 #define FE_INEXACT      FE_INEXACT
  37   };
  38
  39 #define FE_ALL_EXCEPT \
  40         (FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
  41
  42 /* The ix87 FPU supports all of the four defined rounding modes.  We
  43    use again the bit positions in the FPU control word as the values
  44    for the appropriate macros.  */
  45 enum
  46   {
  47     FE_TONEAREST = 0,
  48 #define FE_TONEAREST    FE_TONEAREST
  49     FE_DOWNWARD = 0x400,
  50 #define FE_DOWNWARD     FE_DOWNWARD
  51     FE_UPWARD = 0x800,
  52 #define FE_UPWARD       FE_UPWARD
  53     FE_TOWARDZERO = 0xc00
  54 #define FE_TOWARDZERO   FE_TOWARDZERO
  55   };
  56
  57
  58 /* Type representing exception flags.  */
  59 typedef unsigned short int fexcept_t;
  60
  61
  62 /* Type representing floating-point environment.  This structure
  63    corresponds to the layout of the block written by the `fstenv'
  64    instruction and has additional fields for the contents of the MXCSR
  65    register as written by the `stmxcsr' instruction.  */
  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 #ifdef __x86_64__
  82     unsigned int __mxcsr;
  83 #endif
  84   }
  85 fenv_t;
  86
  87 /* If the default argument is used we use this value.  */
  88 #define FE_DFL_ENV      ((const fenv_t *) -1)
  89
  90 #ifdef __USE_GNU
  91 /* Floating-point environment where none of the exception is masked.  */
  92 # define FE_NOMASK_ENV  ((const fenv_t *) -2)
  93 #endif
  94
  95
  96 #ifdef __USE_EXTERN_INLINES
  97 __BEGIN_DECLS
  98
  99 /* Optimized versions.  */
 100 extern int __REDIRECT_NTH (__feraiseexcept_renamed, (int), feraiseexcept);
 101 __extern_inline int
 102 __NTH (feraiseexcept (int __excepts))
 103 {
 104   if (__builtin_constant_p (__excepts)
 105       && (__excepts & ~(FE_INVALID | FE_DIVBYZERO)) == 0)
 106     {
 107       if ((FE_INVALID & __excepts) != 0)
 108         {
 109           /* One example of a invalid operation is 0.0 / 0.0.  */
 110           float __f = 0.0;
 111
 112 # ifdef __SSE_MATH__
 113           __asm__ __volatile__ ("divss %0, %0 " : : "x" (__f));
 114 # else
 115           __asm__ __volatile__ ("fdiv %%st, %%st(0); fwait"
 116                                 : "=t" (__f) : "0" (__f));
 117 # endif
 118           (void) &__f;
 119         }
 120       if ((FE_DIVBYZERO & __excepts) != 0)
 121         {
 122           float __f = 1.0;
 123           float __g = 0.0;
 124
 125 # ifdef __SSE_MATH__
 126           __asm__ __volatile__ ("divss %1, %0" : : "x" (__f), "x" (__g));
 127 # else
 128           __asm__ __volatile__ ("fdivp %%st, %%st(1); fwait"
 129                                 : "=t" (__f) : "0" (__f), "u" (__g) : "st(1)");
 130 # endif
 131           (void) &__f;
 132         }
 133
 134       return 0;
 135     }
 136
 137   return __feraiseexcept_renamed (__excepts);
 138 }
 139
 140 __END_DECLS
 141 #endif