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

;; samples that hit 256 wrap in the graphic to display as zero
;; exponential 0.8 enhances contrast a bit
(let ((a (make-vector 257 0)))
  (dotimes (v 256)
    (aset a v (floor (* 256 (expt (/ v 256.0) 0.8)))))
  (define-inline contrast (v)
    (aref a v)))

(defconst +1fx+ (expt 2 12))

(define-inline fx (x)
  (* x +1fx+))

(define-inline fx2 (n d)
  (/ (* n +1fx+) d))

(defconst +4fx+ (fx 4))

(define-inline fx* (l r)
  (/ (* l r) +1fx+))

(define-inline fx^2 (x)
  (fx* x x))

(define-inline mandelbrot1 (cx cy)
  (let ((zr 0)
	(zi 0)
	(v 0)
	zr^2
	zi^2)
    (while (and (< v 256) (<= (+ (setq zr^2 (fx^2 zr)) (setq zi^2 (fx^2 zi))) +4fx+))
      (setq v (1+ v))
      (let ((tmp (+ zr^2 (- zi^2) cx)))
	(setq zi (+ (* (fx* zr zi) 2) cy))
	(setq zr tmp)))
    v))

(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 (fx2 -25 10))
          (y0 (fx2 -15 10)))
      (let ((dxp (/ (fx 4) w))
	    (dyp (/ (fx 3) h)))
        (dotimes (y h)
	  (let ((cy (+ y0 (* dyp y))))
	    (dotimes (x w)
	      (let ((v (contrast (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)
;;(mandelbrot 320 200)
;;(profiler-stop)
;;(profiler-report)

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

;; (benchmark-run 1 (mandelbrot 320 200))










































































































;;(32.898215598 2 0.09366582000001245)
;;(51.629763289 2 0.09165389300000015)