bsd man page for fperr

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)