/*


*/

#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>

#define BTN_PIN 5
#define TFT_DC 2
#define TFT_CS 15
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

typedef int16_t fp_t;
#define FP_FRACTBITS  8

#define FP_FACTOR ((fp_t)1 << FP_FRACTBITS)
#define FLOAT2FP(f)   ((fp_t)((f) * FP_FACTOR))
#define FP2FLOAT(fp)  (fp * 1.0f/FP_FACTOR)

#define FP_MUL(a, b)  ((a) * (b) / FP_FACTOR)
#define FP_DIV(a, b)  ((a) * FP_FACTOR / (b))

void setup() {
  pinMode(BTN_PIN, INPUT_PULLUP);

  tft.begin();
  tft.setRotation(1);

  tft.setTextColor(ILI9341_WHITE);
  tft.setTextSize(2);
  tft.print("Start");
  
  Serial.begin(115200);
  Serial.printf("Start !\n");
}

void loop() {
  drawMandelbrot();

  delay(100);
}

int mandelbrotPixel(fp_t cRe_fp, fp_t cIm_fp) {
  fp_t zRe_fp = cRe_fp;
  fp_t zIm_fp = cIm_fp;

  int n;
  const int MAX_ITER = 255;
  for (n = 0; n < MAX_ITER; n++) {
    fp_t zRe2_fp = FP_MUL(zRe_fp, zRe_fp);
    fp_t zIm2_fp = FP_MUL(zIm_fp, zIm_fp);

    if (zRe2_fp + zIm2_fp > FLOAT2FP(4.0))
      break;
    zIm_fp = 2 * FP_MUL(zRe_fp, zIm_fp) + cIm_fp;
    zRe_fp = zRe2_fp - zIm2_fp + cRe_fp;
  }
  return n;
}

void drawMandelbrot() {
  const int WIDTH = 320;
  const int HEIGHT = 240;

  uint16_t framebuffer[WIDTH * HEIGHT];
  
  fp_t minRe_fp = FLOAT2FP(-2.0);
  fp_t maxRe_fp = FLOAT2FP(1.0);
  fp_t minIm_fp = FLOAT2FP(-1.2);
  fp_t maxIm_fp = minIm_fp + (maxRe_fp - minRe_fp) * HEIGHT / WIDTH;

  unsigned long startTime = micros();
  Serial.printf("Start drawing at %ul \n", startTime);
  for (int y = 0; y < HEIGHT; y++) {
    fp_t cIm_fp = map(y, 0, HEIGHT-1, maxIm_fp, minIm_fp);
    
    for (int x = 0; x < WIDTH; x++) {
      fp_t cRe_fp = map(x, 0, WIDTH-1, minRe_fp, maxRe_fp);

      int n = mandelbrotPixel(cRe_fp, cIm_fp);
      uint16_t color = tft.color565((n % 32) * 8, (n % 64) * 4, (n % 128) * 2);
      //tft.drawPixel(x, y, color);
      framebuffer[y * WIDTH + x] = color;
    }
  }
  tft.drawRGBBitmap(0, 0, framebuffer, WIDTH, HEIGHT);
  unsigned long endTime = micros();
  unsigned long computationTime = endTime - startTime;
  Serial.printf("Done in %ul ms \n", computationTime / 1000);

  tft.fillRect(0, 0, 320, 20, ILI9341_BLACK);
  tft.setCursor(0, 0);
  tft.setTextColor(ILI9341_WHITE);
  tft.setTextSize(2);
  tft.print("Time: ");
  tft.print(computationTime/1000000.0);
  tft.print(" s");
}