;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/terror-3/ev3-motor-speed.el

(require 'ev3-motor)

(defun speed-mod (inc)
  (let*((left-speed      (get-motor-speed 'left))
        (right-speed     (get-motor-speed 'right))
        (change          0.1)
        (factor          (1+ (if inc change (- change))))
        (left-speed-new  (round (* factor left-speed)))
        (right-speed-new (round (* factor right-speed))) )
    (if (= 0 left-speed-new right-speed-new)
        (let*((min 100)
              (speed (if inc min (- min))) )
          (set-motor-both speed))
      (set-motor-both left-speed-new right-speed-new) )))

(defun ev3-speed-up ()
  (interactive)
  (speed-mod t) )

(defun ev3-speed-down ()
  (interactive)
  (speed-mod nil) )

(provide 'ev3-motor-speed)