feupdateenv(3) [netbsd man page]

FEGETENV(3)						   BSD Library Functions Manual 					       FEGETENV(3)

NAME

     fegetenv, feholdexcept, fesetenv, feupdateenv -- floating-point environment save and restore

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <fenv.h>
     #pragma STDC FENV_ACCESS ON

     int
     fegetenv(fenv_t *envp);

     int
     feholdexcept(fenv_t *envp);

     int
     fesetenv(const fenv_t *envp);

     int
     feupdateenv(const fenv_t *envp);

DESCRIPTION

     The floating-point environment includes exception flags and masks, the current rounding mode, and other architecture-specific settings.  How-
     ever, it does not include the floating-point register file.

     The fegetenv() function stores the current floating-point environment in the object pointed to by envp, whereas feholdexcept() saves the cur-
     rent environment, then clears all exception flags and masks all floating-point exceptions.

     The fesetenv() function restores a previously saved environment.  The feupdateenv() function restores a saved environment as well, but it
     also raises any exceptions that were set in the environment it replaces.

     The feholdexcept() function is often used with feupdateenv() or fesetenv() to suppress spurious exceptions that occur as a result of interme-
     diate computations.  An example in fenv(3) demonstrates how to do this.

RETURN VALUES

     The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions return 0 if they succeed, and non-zero otherwise.

SEE ALSO

     feclearexcept(3), fenv(3), feraiseexcept(3), fesetenv(3), fetestexcept(3), fpgetmask(3), fpsetmask(3)

STANDARDS

     The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions conform to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY

     These routines first appeared in FreeBSD 5.3 and NetBSD 6.0.

BSD
								    May 8, 2004 							       BSD

FEGETENV(3)						   BSD Library Functions Manual 					       FEGETENV(3)

NAME

     fegetenv, feholdexcept, fesetenv, feupdateenv -- functions providing access to the floating-point environment.

SYNOPSIS

     #include <fenv.h>
     #pragma STDC FENV_ACCESS ON

     int
     fegetenv(fenv_t *envp);

     int
     feholdexcept(fenvt_t *envp);

     int
     fesetenv(fenv_t *envp);

     int
     feupdateenv(fenv_t *envp);

DESCRIPTION

     These functions provide the means to manage the entire floating-point environment--including both status flags and control modes--as a single
     entity.

     The fegetenv() function attempts to store the current floating-point environment in the object pointed to by envp.  It returns zero if the
     environment was successfully stored, and a nonzero value otherwise.

     The feholdexcept() function saves the current floating-point environment in the object pointed to by envp, clears the floating-point status
     flags, and then installs a "non-stop" mode, if available, under which no traps are taken for floating-point exceptions (as is the case in
     default IEEE-754 floating-point execution).  It returns zero if and only if such a mode was successfully installed.

     The fesetenv() function attempts to establish the floating-point environment represented by the object pointed to by envp.  This object shall
     have been set by a call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>.  Note that
     this function merely installs the floating-point status flags represented by its argument, and does not raise the corresponding floating-
     point exceptions.	It returns zero if and only if the environment pointed to by envp was successfully installed.

     The feupdateenv() function attempts to save the currently raised floating-point flags, install the floating-point environment represented by
     *envp, and then raise the floating-point exceptions corresponding to the saved flags.  The object pointed to by envp shall have been set by a
     call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>.  It returns zero if and only if
     all of the specified actions were successfully carried out.

SEE ALSO

     fenv(3), feclearexcept(3), fegetexceptflag(3), fegetround(3), feraiseexcept(3), fesetexceptflag(3), fesetround(3), feraiseexcept(3)

STANDARDS

     These functions conform to ISO/IEC 9899:TC3.

BSD
								    May 9, 2011 							       BSD