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feenableexcept, fedisableexcept, fegetexcept - floating-point exception

 

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 han‐
      dler 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.
      The feenableexcept(), fedisableexcept(), and fegetexcept() functions
      return a bitmap of the exceptions that were unmasked prior to the call.
      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 infor‐
      mation about the exception-causing instruction, or to determine whether
      that instruction should be reexecuted after returning from the handler.
 

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Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.