sysdeps/x86/fpu/bits/fenv.h

   1 /* Copyright (C) 1997-2015 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 =
  27 #define FE_INVALID      0x01
  28       FE_INVALID,
  29     __FE_DENORM = 0x02,
  30     FE_DIVBYZERO =
  31 #define FE_DIVBYZERO    0x04
  32       FE_DIVBYZERO,
  33     FE_OVERFLOW =
  34 #define FE_OVERFLOW     0x08
  35       FE_OVERFLOW,
  36     FE_UNDERFLOW =
  37 #define FE_UNDERFLOW    0x10
  38       FE_UNDERFLOW,
  39     FE_INEXACT =
  40 #define FE_INEXACT      0x20
  41       FE_INEXACT
  42   };
  43
  44 #define FE_ALL_EXCEPT \
  45         (FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
  46
  47 /* The ix87 FPU supports all of the four defined rounding modes.  We
  48    use again the bit positions in the FPU control word as the values
  49    for the appropriate macros.  */
  50 enum
  51   {
  52     FE_TONEAREST =
  53 #define FE_TONEAREST    0
  54       FE_TONEAREST,
  55     FE_DOWNWARD =
  56 #define FE_DOWNWARD     0x400
  57       FE_DOWNWARD,
  58     FE_UPWARD =
  59 #define FE_UPWARD       0x800
  60       FE_UPWARD,
  61     FE_TOWARDZERO =
  62 #define FE_TOWARDZERO   0xc00
  63       FE_TOWARDZERO
  64   };
  65
  66
  67 /* Type representing exception flags.  */
  68 typedef unsigned short int fexcept_t;
  69
  70
  71 /* Type representing floating-point environment.  This structure
  72    corresponds to the layout of the block written by the `fstenv'
  73    instruction and has additional fields for the contents of the MXCSR
  74    register as written by the `stmxcsr' instruction.  */
  75 typedef struct
  76   {
  77     unsigned short int __control_word;
  78     unsigned short int __glibc_reserved1;
  79     unsigned short int __status_word;
  80     unsigned short int __glibc_reserved2;
  81     unsigned short int __tags;
  82     unsigned short int __glibc_reserved3;
  83     unsigned int __eip;
  84     unsigned short int __cs_selector;
  85     unsigned int __opcode:11;
  86     unsigned int __glibc_reserved4:5;
  87     unsigned int __data_offset;
  88     unsigned short int __data_selector;
  89     unsigned short int __glibc_reserved5;
  90 #ifdef __x86_64__
  91     unsigned int __mxcsr;
  92 #endif
  93   }
  94 fenv_t;
  95
  96 /* If the default argument is used we use this value.  */
  97 #define FE_DFL_ENV      ((const fenv_t *) -1)
  98
  99 #ifdef __USE_GNU
 100 /* Floating-point environment where none of the exception is masked.  */
 101 # define FE_NOMASK_ENV  ((const fenv_t *) -2)
 102 #endif
 103
 104
 105 #ifdef __USE_EXTERN_INLINES
 106 __BEGIN_DECLS
 107
 108 /* Optimized versions.  */
 109 extern int __REDIRECT_NTH (__feraiseexcept_renamed, (int), feraiseexcept);
 110 __extern_always_inline void
 111 __NTH (__feraiseexcept_invalid_divbyzero (int __excepts))
 112 {
 113   if ((FE_INVALID & __excepts) != 0)
 114     {
 115       /* One example of an invalid operation is 0.0 / 0.0.  */
 116       float __f = 0.0;
 117
 118 # ifdef __SSE_MATH__
 119       __asm__ __volatile__ ("divss %0, %0 " : : "x" (__f));
 120 # else
 121       __asm__ __volatile__ ("fdiv %%st, %%st(0); fwait"
 122                             : "=t" (__f) : "0" (__f));
 123 # endif
 124       (void) &__f;
 125     }
 126   if ((FE_DIVBYZERO & __excepts) != 0)
 127     {
 128       float __f = 1.0;
 129       float __g = 0.0;
 130
 131 # ifdef __SSE_MATH__
 132       __asm__ __volatile__ ("divss %1, %0" : : "x" (__f), "x" (__g));
 133 # else
 134       __asm__ __volatile__ ("fdivp %%st, %%st(1); fwait"
 135                             : "=t" (__f) : "0" (__f), "u" (__g) : "st(1)");
 136 # endif
 137       (void) &__f;
 138     }
 139 }
 140 __extern_inline int
 141 __NTH (feraiseexcept (int __excepts))
 142 {
 143   if (__builtin_constant_p (__excepts)
 144       && (__excepts & ~(FE_INVALID | FE_DIVBYZERO)) == 0)
 145     {
 146       __feraiseexcept_invalid_divbyzero (__excepts);
 147       return 0;
 148     }
 149
 150   return __feraiseexcept_renamed (__excepts);
 151 }
 152
 153 __END_DECLS
 154 #endif