;;;; terminal.scm


(define-constant TCONTROL_REGISTER #xc000)
(define-constant TINPUT_CHAR #xc001)
(define-constant TOUTPUT_CHAR #xc002)
(define-constant TINPUT_CHAR_BIT #x80)
(define-constant TOUTPUT_CHAR_BIT #x40)

(define stdin (current-input-port))
(define stdout (current-output-port))

(define (poll-terminal-device p)
  (let* ((mem (processor-memory p))
	 (cr (u8vector-ref mem TCONTROL_REGISTER)))
    (cond ((zero? (fxand cr TINPUT_CHAR_BIT))
	   (let ((c (read-char stdin)))
	     (when (eof-object? c)
	       (error "EOF from terminal"))
	     (if (char=? c #\newline)
		 (set! c #\return)
		 (set! c (char-upcase c)))
	     (u8vector-set! mem TINPUT_CHAR (fxand #x7f (char->integer c)))))
	  ((zero? (fxand cr TOUTPUT_CHAR_BIT))
	   (write-char (integer->char (fxand #x7f (u8vector-ref mem TOUTPUT_CHAR))) stdout)
	   (flush-output stdout)))
    (u8vector-set! mem TCONTROL_REGISTER (fxior cr (fxior TINPUT_CHAR_BIT TOUTPUT_CHAR_BIT)))))