;
; Adafruit CLUE TFT colour display plotting demo - see http://www.ulisp.com/show?2ZD1
;

; Pins used for CLUE display
(defvar dc 32)
(defvar cs 31)

; Display commands
(defvar CASET #x2A)
(defvar RASET #x2B)
(defvar RAMWR #x2C)

; Display offsets and dimensions
(defvar yoff 0)
(defvar xoff 80)
(defvar xsize 240)
(defvar ysize 240)
(defvar invert 1)
(defvar rot 6)

; Convert red, green, blue components 0 to 255 to a 16-bit 565 RGB value
(defun rgb (r g b)
 (logior (ash (logand r #xf8) 8) (ash (logand g #xfc) 3) (ash b -3)))

; Write a command with optional data bytes
(defun cmd (c &rest data)
  (with-spi (str cs 4000 1 0 1)
    (digitalwrite dc 0)
    (write-byte c str)
    (digitalwrite dc 1)
    (dolist (d data)
      (write-byte d str))))

; Initialize the display
(defun init ()
  (pinmode dc t)
  (cmd #x01)            ; Software reset
  (delay 150)           ; delay 150 ms
  (cmd #x11)            ; Out of sleep mode
  (delay 10)            ; delay 10 ms
  (cmd #x3A #x55)       ; Set color mode - 16-bit color
  (cmd (+ #x20 invert)) ; Invert?
  (cmd #x36 (ash rot 5)); Set orientation
  (cmd #x29)            ; Display on
  (delay 10))

; Plot point at x,y
(defun point (x y colour)
  (let ((v (+ yoff y)) (h (+ xoff x)))
    (cmd CASET (ash v -8) v (ash v -8) v)
    (cmd RASET (ash h -8) h (ash h -8) h)
    (cmd RAMWR (ash colour -8) colour)))

(defun plot ()
  (dotimes (xx 240)
    (let ((x (- xx 120)))
      (dotimes (yy 240)
        (let* ((y (- yy 120))
               (f (truncate (+ (* x (+ x y)) (* y y)) 8)))
          (point xx yy (rgb (+ f 160) f (+ f 80))))))))