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+;"tek40.scm", Tektronix 4000 series graphics support in Scheme.
+;Copyright (C) 1992, 1994 Aubrey Jaffer
+;
+;Permission to copy this software, to redistribute it, and to use it
+;for any purpose is granted, subject to the following restrictions and
+;understandings.
+;
+;1.  Any copy made of this software must include this copyright notice
+;in full.
+;
+;2.  I have made no warrantee or representation that the operation of
+;this software will be error-free, and I am under no obligation to
+;provide any services, by way of maintenance, update, or otherwise.
+;
+;3.  In conjunction with products arising from the use of this
+;material, there shall be no use of my name in any advertising,
+;promotional, or sales literature without prior written consent in
+;each case.
+
+;THIS FILE NEEDS MORE WORK.
+
+;The Tektronix 4000 series graphics protocol gives the user a 1024 by
+;1024 square drawing area.  The origin is in the lower left corner of
+;the screen.  Increasing y is up and increasing x is to the right.
+
+;The graphics control codes are sent over the current-output-port and
+;can be mixed with regular text and ANSI or other terminal control
+;sequences.
+
+;  (tek40:init)						procedure
+
+(define (tek40:init) 'noop)
+
+(define esc-string (string (integer->char #o33)))
+
+(define tek40:graphics-str
+  (string-append
+   (string slib:form-feed)
+   esc-string  (string (integer->char #o14))
+   ;; clear the screen
+   ))
+
+(define (tek40:graphics) (display tek40:graphics-str) (force-output))
+
+(define (tek40:text)
+  (tek40:move 0 12)
+  (write-char (integer->char #o37)))
+
+(define (tek40:linetype linetype)
+  (cond ((or (negative? linetype) (> linetype 15))
+	 (slib:error "bad linetype" linetype))
+	(else
+	 (display esc-string)
+	 (write-char (integer->char (+ (char->integer #\`) linetype))))))
+
+(define (tek40:move x y)
+  (write-char (integer->char #o35))
+  (tek40:draw x y))
+
+(define (tek40:draw x y)
+  (display (string
+	    (integer->char (+ #x20 (quotient y 32)))
+	    (integer->char (+ #x60 (remainder y 32)))
+	    (integer->char (+ #x20 (quotient x 32)))
+	    (integer->char (+ #x40 (remainder x 32))))))
+
+(define (tek40:put-text x y str)
+  (tek40:move x (+ y -11))
+  (write-char (integer->char #o37))
+  (display str))
+
+(define (tek40:reset) (display tek40:graphics-str) (force-output))
+
+(define (tek40:test)
+  (tek40:init)
+;  (tek40:reset)
+  (tek40:graphics)
+  (tek40:linetype 0)
+  (tek40:move 100 100)
+  (tek40:draw 200 100)
+  (tek40:draw 200 200)
+  (tek40:draw 100 200)
+  (tek40:draw 100 100)
+  (do ((i 0 (+ 1 i)))
+      ((> i 15))
+    (tek40:linetype i)
+    (tek40:move (+ (* 50 i) 100) 100)
+    (tek40:put-text (+ (* 50 i) 100) 100 (number->string i))
+    (tek40:move (+ (* 50 i) 100) 100)
+    (tek40:draw (+ (* 50 i) 200) 200))
+  (tek40:linetype 0)
+  (tek40:text))