On Alpha systems, returns information about the exception context
    for a given arithmetic exception. There are two forms the signal
    argument vectors: one for use with 32-bit addresses and one for
    use with 64-bit addresses.

    For more information, see the section "Signal Argument Vector" in
    the HP OpenVMS Calling Standard.

    Format

      SYS$GET_ARITH_EXCEPTION  sigarg ,mcharg ,buffer

    C Prototype

      int sys$get_arith_exception  (void *sigarg, void *mcharg, void

                                   *buffer);

1 - Arguments

 sigarg

    OpenVMS usage:signal array
    type:         vector_longword_signed
    access:       read only
    mechanism:    by reference
    Address of the signal array for the given arithmetic exception.

 mcharg

    OpenVMS usage:mech array
    type:         vector_quadword_unsigned
    access:       read only
    mechanism:    by reference
    Address of the mechanism array for the given arithmetic
    exception.

 buffer

    OpenVMS usage:vector_quadword
    type:         vector_quadword_unsigned
    access:       write only
    mechanism:    by descriptor
    Four-quadword buffer to receive additional exception context.
    The buffer argument is the address of a descriptor that points to
    this buffer.