fegetexcept(3) [netbsd man page]

FEENABLEEXCEPT(3)					   BSD Library Functions Manual 					 FEENABLEEXCEPT(3)

NAME

     feenableexcept, fedisableexcept, fegetexcept -- floating-point exception masking

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

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

     int
     feenableexcept(int excepts);

     int
     fedisableexcept(int excepts);

     int
     fegetexcept(void);

DESCRIPTION

     The feenableexcept() and fedisableexcept() functions unmask and mask (respectively) exceptions specified in excepts.  The fegetexcept() func-
     tion returns the current exception mask.  All exceptions are masked by default.

     Floating-point operations that produce unmasked exceptions will trap, and a SIGFPE will be delivered to the process.  By installing a signal
     handler for SIGFPE, applications can take appropriate action immediately without testing the exception flags after every operation.  Note
     that the trap may not be immediate, but it should occur before the next floating-point instruction is executed.

     For all of these functions, the possible types of exceptions include those described in fenv(3).  Some architectures may define other types
     of floating-point exceptions.

RETURN VALUES

     The feenableexcept(), fedisableexcept(), and fegetexcept() functions return a bitmap of the exceptions that were unmasked prior to the call.

SEE ALSO

     sigaction(2), feclearexcept(3), feholdexcept(3), fenv(3), feupdateenv(3)

BUGS

     Functions in the standard library may trigger exceptions multiple times as a result of intermediate computations; however, they generally do
     not trigger spurious exceptions.

     No interface is provided to permit exceptions to be handled in nontrivial ways.  There is no uniform way for an exception handler to access
     information about the exception-causing instruction, or to determine whether that instruction should be reexecuted after returning from the
     handler.

BSD
								  March 16, 2005							       BSD

FECLEAREXCEPT(3)					   BSD Library Functions Manual 					  FECLEAREXCEPT(3)

NAME

     feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag, fetestexcept -- floating-point exception flag manipulation

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

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

     int
     feclearexcept(int excepts);

     int
     fegetexceptflag(fexcept_t *flagp, int excepts);

     int
     feraiseexcept(int excepts);

     int
     fesetexceptflag(const fexcept_t *flagp, int excepts);

     int
     fetestexcept(int excepts);

DESCRIPTION

     The feclearexcept() routine clears the floating-point exception flags specified by excepts, whereas feraiseexcept() raises the specified
     exceptions.  Raising an exception causes the corresponding flag to be set, and a SIGFPE is delivered to the process if the exception is
     unmasked.

     The fetestexcept() function determines which flags are currently set, of those specified by excepts.

     The fegetexceptflag() function stores the state of the exception flags specified in excepts in the opaque object pointed to by flagp.  Simi-
     larly, fesetexceptflag() changes the specified exception flags to reflect the state stored in the object pointed to by flagp.  Note that the
     flags restored with fesetexceptflag() must be a (not necessarily proper) subset of the flags recorded by a prior call to fegetexceptflag().

     For all of these functions, the possible types of exceptions include those described in fenv(3).  Some architectures may define other types
     of floating-point exceptions.

IMPLEMENTATION NOTES

     On some architectures, raising an overflow or underflow exception also causes an inexact exception to be raised.  In these cases, the over-
     flow or underflow will be raised first.

     The fegetexceptflag() and fesetexceptflag() routines are preferred to fetestexcept() and feraiseexcept(), respectively, for saving and
     restoring exception flags.  The latter do not re-raise exceptions and may preserve architecture-specific information such as addresses where
     exceptions occurred.

RETURN VALUES

     The feclearexcept(), fegetexceptflag(), feraiseexcept(), and fesetexceptflag() functions return 0 upon success, and non-zero otherwise.  The
     fetestexcept() function returns the bitwise OR of the values of the current exception flags that were requested.

SEE ALSO

     sigaction(2), feholdexcept(3), fenv(3), feupdateenv(3), fpgetsticky(3)

STANDARDS

     The feclearexcept(), fegetexceptflag(), feraiseexcept(), fesetexceptflag(), and fetestexcept() routines conform to ISO/IEC 9899:1999
     (``ISO C99'').

HISTORY

     These functions first appeared in FreeBSD 5.3 and NetBSD 6.0.

BSD
								    May 8, 2004 							       BSD