fperr(2) [bsd man page]

FPERR(2)							System Calls Manual							  FPERR(2)

NAME

       fperr - get floating-point error registers (2BSD)

SYNOPSIS

       #include <pdp/fperr.h>

       struct fperr
       {
	    short     f_fec;
	    caddr_t   f_fea;
       };

       fperr(fpe)
       struct fperr *fpe;

DESCRIPTION

       Fperr  returns  the contents of the floating-point processor's error registers as they were following the last floating exception generated
       by the calling process.	The registers are stored in the structure pointed to by fpe.

       This call is required because the error registers in the PDP-11 floating-point processor are read-only.	Thus, they may be changed by  some
       other  process  between	the time that the current process generates an exception and the time that it reads the registers.  Therefore, the
       system saves their state at the time of an exception.

       The values returned are valid only after a floating-point exception.

ERRORS

       [EINVAL]       The kernel has not been compiled for a processor with floating point.

SEE ALSO

       Ed Gould, Jim Reeds, Vance Vaughan, UNIX Problems with Floating Point Processors

BUGS

       Fperr is unique to the PDP-11 and 2BSD; its use is discouraged.

3rd Berkeley Distribution					 January 22, 1987							  FPERR(2)

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)