Edit: /usr/include/bits/fenv.h (4605B)
/* Copyright (C) 1997-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
. */
#ifndef _FENV_H
# error "Never use
directly; include instead."
#endif
/* Define bits representing the exception. We use the bit positions
of the appropriate bits in the FPU control word. */
enum
{
FE_INVALID =
#define FE_INVALID 0x01
FE_INVALID,
__FE_DENORM = 0x02,
FE_DIVBYZERO =
#define FE_DIVBYZERO 0x04
FE_DIVBYZERO,
FE_OVERFLOW =
#define FE_OVERFLOW 0x08
FE_OVERFLOW,
FE_UNDERFLOW =
#define FE_UNDERFLOW 0x10
FE_UNDERFLOW,
FE_INEXACT =
#define FE_INEXACT 0x20
FE_INEXACT
};
#define FE_ALL_EXCEPT \
(FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
/* The ix87 FPU supports all of the four defined rounding modes. We
use again the bit positions in the FPU control word as the values
for the appropriate macros. */
enum
{
FE_TONEAREST =
#define FE_TONEAREST 0
FE_TONEAREST,
FE_DOWNWARD =
#define FE_DOWNWARD 0x400
FE_DOWNWARD,
FE_UPWARD =
#define FE_UPWARD 0x800
FE_UPWARD,
FE_TOWARDZERO =
#define FE_TOWARDZERO 0xc00
FE_TOWARDZERO
};
/* Type representing exception flags. */
typedef unsigned short int fexcept_t;
/* Type representing floating-point environment. This structure
corresponds to the layout of the block written by the `fstenv'
instruction and has additional fields for the contents of the MXCSR
register as written by the `stmxcsr' instruction. */
typedef struct
{
unsigned short int __control_word;
unsigned short int __glibc_reserved1;
unsigned short int __status_word;
unsigned short int __glibc_reserved2;
unsigned short int __tags;
unsigned short int __glibc_reserved3;
unsigned int __eip;
unsigned short int __cs_selector;
unsigned int __opcode:11;
unsigned int __glibc_reserved4:5;
unsigned int __data_offset;
unsigned short int __data_selector;
unsigned short int __glibc_reserved5;
#ifdef __x86_64__
unsigned int __mxcsr;
#endif
}
fenv_t;
/* If the default argument is used we use this value. */
#define FE_DFL_ENV ((const fenv_t *) -1)
#ifdef __USE_GNU
/* Floating-point environment where none of the exception is masked. */
# define FE_NOMASK_ENV ((const fenv_t *) -2)
#endif
#if __GLIBC_USE (IEC_60559_BFP_EXT)
/* Type representing floating-point control modes. */
typedef struct
{
unsigned short int __control_word;
unsigned short int __glibc_reserved;
unsigned int __mxcsr;
}
femode_t;
/* Default floating-point control modes. */
# define FE_DFL_MODE ((const femode_t *) -1L)
#endif
#ifdef __USE_EXTERN_INLINES
__BEGIN_DECLS
/* Optimized versions. */
#ifndef _LIBC
extern int __REDIRECT_NTH (__feraiseexcept_renamed, (int), feraiseexcept);
#endif
__extern_always_inline void
__NTH (__feraiseexcept_invalid_divbyzero (int __excepts))
{
if ((FE_INVALID & __excepts) != 0)
{
/* One example of an invalid operation is 0.0 / 0.0. */
float __f = 0.0;
# ifdef __SSE_MATH__
__asm__ __volatile__ ("divss %0, %0 " : "+x" (__f));
# else
__asm__ __volatile__ ("fdiv %%st, %%st(0); fwait"
: "=t" (__f) : "0" (__f));
# endif
(void) &__f;
}
if ((FE_DIVBYZERO & __excepts) != 0)
{
float __f = 1.0;
float __g = 0.0;
# ifdef __SSE_MATH__
__asm__ __volatile__ ("divss %1, %0" : "+x" (__f) : "x" (__g));
# else
__asm__ __volatile__ ("fdivp %%st, %%st(1); fwait"
: "=t" (__f) : "0" (__f), "u" (__g) : "st(1)");
# endif
(void) &__f;
}
}
__extern_inline int
__NTH (feraiseexcept (int __excepts))
{
if (__builtin_constant_p (__excepts)
&& (__excepts & ~(FE_INVALID | FE_DIVBYZERO)) == 0)
{
__feraiseexcept_invalid_divbyzero (__excepts);
return 0;
}
return __feraiseexcept_renamed (__excepts);
}
__END_DECLS
#endif