;;; the modifications needed to get the read command to work properly
;;; are indicated with "; ****" comments at the end of the line.

(defun chint ()
  ;; this is the real thing, find out what caused the irq
  (if (not (boolean (read rtnreg redy)))
      (device-error "Ready bit not set after interrupt occurred."))
  (if (boolean (read rtnreg errb))
      (IF (EQ (eproc) :LOOP) (RETURN-FROM CHINT NIL)))
  (cond ((boolean (read rtnreg wrcp))
	 (message "write complete")
	 ;; get buffer size,  odd/even
	 (setq *xlen* (- *WRLEN* (dpb (read bfszu) (byte 8 8) (read bfszl))))
	 (cond ((boolean (read err1 odby))
		(setq *xodd* t)
		(message "length = ~D bytes" (1- (* *xlen* 2))))
	       ('else
		(setq *xodd* nil)
		(message "length = ~D bytes" (* *xlen* 2))))
	 (PROCESS-DATA (MBU:USER-MULTIBUS-DMA-BUFFER.ARRAY *XPNT*)
		       (- (* *XLEN* 2)
			  (IF *XODD* 1 0)))
	 ;; set up DE status
	 (write comsta *de*)
	 (write chadd *subch*)
	 (modify mulcom go 1 endg 1))
	((boolean (read rtnreg rdcp))
	 (cond ((boolean (read rtnreg endp))
		(message "Read complete and ending presented"))
	       ('else
		(message "Read complete")
		(message "length = ~D bytes" (* 2 (dpb (read bfszu) (byte 8 8) (read bfszl))))))
	 (cond ((boolean (read rtnreg crcv))	; ****
		(message "also command received")	; ****
		(pcom))				; ****
	       ('else				; ****
		;; CE, DE already presented on read, just issue GO
		(modify mulcom go 1))))		; ****
	((boolean (read rtnreg endp))
	 (cond ((boolean (read rtnreg crcv))
		(message "ending presented and command received")
		(pcom))
	       ('else
		(message "Ending presented")
		;; just issue GO
		(modify mulcom go 1))))
	((boolean (read rtnreg crcv))
	 ;; command received,
	 (pcom))
	('else
	 ;; Command not valid or immediate, error
	 (message "Not a valid or immediate command.")
	 (pra)
	 (modify mulcom go 1))))