traper(3f) [bsd man page]

TRAPER(3F)																TRAPER(3F)

NAME

       traper - trap arithmetic errors

SYNOPSIS

       integer function traper (mask)

DESCRIPTION

       NOTE: This routine applies only to the VAX.  It is ignored on the PDP11.

       Integer overflow and floating point underflow are not normally trapped during execution. This routine enables these traps by setting status
       bits in the process status word. These bits are reset on entry to a subprogram, and the previous state is restored on  return.	Therefore,
       this  routine  must  be called inside each subprogram in which these conditions should be trapped.  If the condition occurs and trapping is
       enabled, signal SIGFPE is sent to the process. (See signal(3C))

       The argument has the following meaning:

	       value   meaning
		 0     do not trap either condition
		 1     trap integer overflow only
		 2     trap floating underflow only
		 3     trap both the above

       The previous value of these bits is returned.

FILES

       /usr/lib/libF77.a

SEE ALSO

       signal(3C), signal(3F)

4.2 Berkeley Distribution					   May 15, 1985 							TRAPER(3F)

TRPFPE(3F)																TRPFPE(3F)

NAME

       trpfpe, fpecnt - trap and repair floating point faults

SYNOPSIS

       subroutine trpfpe (numesg, rtnval)
       double precision rtnval

       integer function fpecnt ()

       common /fpeflt/ fperr
       logical fperr

DESCRIPTION

       NOTE: This routine applies only to Vax computers.  It is a null routine on the PDP11.

       Trpfpe sets up a signal handler to trap arithmetic exceptions.  If the exception is due to a floating point arithmetic fault, the result of
       the operation is replaced with the rtnval specified.  Rtnval must be a double precision value. For example, ``0d0'' or ``dflmax()''.

       The first numesg occurrences of a floating point arithmetic error will cause a message to be written  to  the  standard	error  file.   Any
       exception that can't be repaired will result in the default action, typically an abort with core image.

       Fpecnt returns the number of faults since the last call to trpfpe.

       The logical value in the common block labelled fpeflt will be set to .true.  each time a fault occurs.

FILES

       /usr/lib/libF77.a

SEE ALSO

       signal(3F), range(3F)

BUGS

       This routine works only for faults, not traps.  This is primarily due to the Vax architecture.

       If  the	operation  involves  changing the stack pointer, it can't be repaired.	This seldom should be a problem with the f77 compiler, but
       such an operation might be produced by the optimizer.

       The POLY and EMOD opcodes are not dealt with.

4.2 Berkeley Distribution					   May 15, 1985 							TRPFPE(3F)