git.sur5r.net Git - cc65/blob - test/ref/mandel.c

   1 /*
   2   !!DESCRIPTION!! mandelbrot test program
   3   !!ORIGIN!!      testsuite
   4   !!LICENCE!!     Public Domain
   5   !!AUTHOR!!      Groepaz/Hitmen
   6 */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10
  11 static unsigned short SCREEN_X;
  12 static unsigned char  SCREEN_Y;
  13
  14 #define MAXCOL     8
  15
  16 #define maxiterations 16
  17
  18 #define fpshift (12)
  19
  20 #define tofp(_x)        ((_x)<<fpshift)
  21 #define fromfp(_x)      ((_x)>>fpshift)
  22 #define fpabs(_x)       (abs(_x))
  23
  24 #define mulfp(_a,_b)    ((((signed long)_a)*(_b))>>fpshift)
  25 #define divfp(_a,_b)    ((((signed long)_a)<<fpshift)/(_b))
  26
  27 unsigned char dither[MAXCOL]={" .*o+0%#"};
  28
  29 void mandelbrot(signed short x1,signed short y1,signed short x2,signed short y2)
  30 {
  31 register signed short  r,r1,i;
  32 register unsigned char count;
  33 register signed short xs,ys,xx,yy;
  34 register signed short x;
  35 register unsigned char y;
  36
  37         /* calc stepwidth */
  38         xs=((x2-x1)/(SCREEN_X));
  39         ys=((y2-y1)/(SCREEN_Y));
  40
  41         yy=y1;
  42         for(y = 0; y < (SCREEN_Y); ++y)
  43         {
  44                 yy+=ys; xx=x1;
  45                 for(x = 0; x < (SCREEN_X); ++x)
  46                 {
  47                     xx+=xs;
  48                     /* do iterations */
  49                     r=0;i=0;
  50                     for(count=0;(count<maxiterations)&&
  51                                 (fpabs(r)<tofp(2))&&
  52                                 (fpabs(i)<tofp(2))
  53                                 ;++count)
  54                     {
  55                             r1 = (mulfp(r,r)-mulfp(i,i))+xx;
  56                             /* i = (mulfp(mulfp(r,i),tofp(2)))+yy; */
  57                             i = (((signed long)r*i)>>(fpshift-1))+yy;
  58                             r=r1;
  59                     }
  60                     if(count==maxiterations)
  61                     {
  62                             printf(" ");
  63                     }
  64                     else
  65                     {
  66                             printf("%c",dither[(count%MAXCOL)]);
  67                     }
  68                 }
  69                     printf("\n");
  70         }
  71 }
  72
  73 int main (void)
  74 {
  75     SCREEN_X = 80;
  76     SCREEN_Y = 40;
  77
  78     /* calc mandelbrot set */
  79     mandelbrot(tofp(-2),tofp(-2),tofp(2),tofp(2));
  80
  81     /* Done */
  82     return 0;
  83 }
  84