10	sub TPU$CALLUSER ( some_integer% , input_string$ , return_string$ )

 !++
 ! FACILITY:	 TPU$calluser routine 
 !
 ! ABSTRACT:	 Provide access to multiple TPU Calluser routines
 !               based on passed integer.
 !               Does a find_image to activate the correct calluser 
 !               then does Callg to it.
 !               Precondition: each integer must have a logical name
 !               associated with it. 0 = TPU$CALLUSER0
 !                                   1 = TPU$CALLUSER1
 !                                   2 = TPU$CALLUSER2 ...
 !--

20	external long    function lib$find_image_symbol  
	external long    function lib$callg
	external integer function lib$signal

	external long    constant ss$_normal
	declare  long    ret_code            ! local return code
	declare  long    send_address        ! address in shareable image

	declare  long    arg_list (3)        ! passed to callg

        suffix$ = str$( some_integer% )    ! get the number as a string

        ! logical name of the shared image 
        shared_image$ = "TPU$CALLUSER" + suffix$ 
        entry_point$ = "TPU$CALLUSER"      ! entry point 

	ret_code = lib$find_image_symbol ( shared_image$ ,    &
                                           entry_point$ ,  &
                                           send_address &
                                         )

	if ret_code = ss$_normal then
	else
		tpu$calluser = ret_code
		exit sub
	end if

	arg_list (0) = 3                    ! number of arguements
 	arg_list (1) = loc ( some_integer% )  ! address 
	arg_list (2) = loc ( input_string$ ) ! address
	arg_list (3) = loc ( return_string$ ) ! address

	ret_code = lib$callg( arg_list (0) by ref , send_address by value )

	if ret_code = ss$_normal then
	else
		return_string$ = ""
	end if

        tpu$calluser = ret_code

999	all_done: 
                 ! return_string$ is defined
	end sub