;;; -*- lexical-binding: t -*-

(define-inline mandelbrot1 (cx cy)
  (let ((zr 0)
	(zi 0)
	(v 0))
    (while (and (< v 256) (<= (+ (* zr zr) (* zi zi)) 4))
      (setq v (1+ v))
      (let ((tmp (+ (* zr zr) (- (* zi zi)) cx)))
	(setq zi (+ (* (* zr zi) 2) cy))
	(setq zr tmp)))
    ;; samples that hit 256 wrap in the graphic to display as zero
    ;; exponential 0.8 enhances contrast a bit
    (floor (* 256 (expt (/ v 256.0) 0.8)))))

(defun mandelbrot (&optional w h)
  (declare (speed 3))
  (interactive)
  (let ((output (make-vector (* w h) 0.0))
        (idx 0))
    (let ((w (or w 1600))
	  (h (or h 1200))
          (x0 -2.5)
	  (y0 -1.5)
	  (dx 4.0)
	  (dy 3.0))
      (let ((dxp (/ dx w))
	    (dyp (/ dy h)))
        (dotimes (y h)
	  (let ((cy (+ y0 (* dyp y))))
	    (dotimes (x w)
	      (let ((v (mandelbrot1 (+ x0 (* dxp x)) cy)))
	        (aset output idx v)
                (setq idx (1+ idx))))))))
    output))

(defun mandelbrot-bench ()
  (interactive)
  (let (output)
    (profiler-start 'cpu+mem)
    (setq output (mandelbrot 320 200))
    (profiler-stop)
    (profiler-report)
    (message "%S" output)))

;;(mandelbrot 320 200)
;;(mandelbrot 640 480)
;;(mandelbrot 1024 768)
;;(mandelbrot)

;; (profiler-start 'mem)
;; (mandelbrot 320 200)
;; (profiler-stop)
;; (profiler-report)

;; (profiler-start 'cpu+mem)
;; (mandelbrot 320 200)
;; (profiler-stop)
;; (profiler-report)

;; (profiler-start 'cpu)
;; (mandelbrot 320 200)
;; (profiler-stop)
;; (profiler-report)

;;(profiler-start 'cpu+mem)
;;(mandelbrot)
;;(profiler-stop)
;;(profiler-report)

;; (benchmark-run 1 (mandelbrot))
;; (15.033354357 15 3.9534469799999954)
;;(120.40541861 1947 93.45048212499998)
;;(128.362728323 1942 93.44881820700004)