#include <stdint.h>
#include <math.h>
#include <stdio.h>

typedef struct
{
  uint8_t r, g, b;
} rgb_t;

#define ZOOM 2
#define SMOOTH 1

#define graphwidth     ((uint16_t) (128 * ZOOM * 3 / 2.5))
#define graphheight    ((uint16_t) (128 * ZOOM))

static void putpixel (uint16_t x, uint16_t y, uint8_t r, uint8_t g, uint8_t b);

static inline uint32_t rgbfromvalue (uint8_t r, uint8_t g, uint8_t b)
{
  uint32_t rgb = 0;
  rgb |= r;
  rgb |= (uint16_t) (g << 8);
  rgb |= (uint32_t) b << 16;
  return rgb;
}
               
void mandelbrot (uint16_t ofsx, uint16_t ofsy)
{
  const uint16_t max_it = 20;
  const float m = 20.0;
  float xmin= -2.2, xmax = 0.8, ymin = -1.25, ymax = 1.25;

  //  alternative Zahlenwerte
  // xmin= -0.5328; xmax= -0.2078; ymin= 0.3742; ymax= 0.892;
  const float dx = (float) (xmax - xmin) / graphwidth;
  const float dy = (float) (ymax - ymin) / graphheight;
  const float dd = sqrtf (dx * dy);

  float jy = ymin;
  for (uint16_t y = 0; y < graphheight; ++y, jy += dd)
    {
      float jx = xmin;
      for (uint16_t x = 0; x < graphwidth; ++x, jx += dd)
        {
          float r, wx = 0.0, wy = 0.0;
          uint16_t it = 0;
          do
            {
              float tx = wx*wx - wy*wy + jx;
              float ty = ldexpf (wx*wy, 1) + jy;
              r = wx*wx + wy*wy;
              wx = tx;
              wy = ty;
              it++;
            } while (r <= m*m && it < max_it);

          rgb_t rgb;
          /*
          if (k < 3) { rgb.r = rgb.g = rgb.b = k * 20; }
          if (k > 2 && k < 35) { rgb.b = k * 9; rgb.g = k; rgb.r = k * 2; }
          if (k > 34) { rgb.r = 128; rgb.g = k * 3; rgb.b = k; }
          */
          if (it >= max_it)
            rgb.r = rgb.g = rgb.b = 0;
          else
            {
              uint8_t c = it & 1 ? 250 : 0;
              if (SMOOTH)
                {
                  c = 252 * (logf (r) / (2 * logf (m)) - 0.99);
                  c = it & 1 ? c : 254 - c;
                }
              rgb.r = rgb.g = rgb.b = c;
            }

          putpixel (ofsx + x, ofsy + y, rgb.r, rgb.g, rgb.b);
        }
    }
}

void putpixel (uint16_t x, uint16_t y, uint8_t r, uint8_t g, uint8_t b)
{
  (void) y;
#ifndef AVRTEST_H
  printf ("%u %u %u%c", r, g, b, x == graphwidth - 1 ? '\n' : ' ');
#else
  LOG_FMT_U16 ("%u ", r);
  LOG_FMT_U16 ("%u ", g);
  LOG_FMT_U16 ("%u", b);
  LOG_STR (x == graphwidth - 1 ? "\n" : " ");
#endif
}

int main (void)
{
  printf ("P3\n");
  printf ("%u %u\n", graphwidth, graphheight);
  printf ("255\n");
  mandelbrot (0, 0);

  return 0;
}