#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <graph.h>
#include <string.h>
#include <conio.h>

static struct videoconfig video_config;

void main (int argc, char *argv[])
{
  if (argc == 1)
     { printf("Usage: turtle <string>\n"
              "\n       <string> = { R | L | M | T }*\n");
       return;
     }
  if (!_setvideomode(_MAXRESMODE))
     { printf("No videomode\n");
       return;
     }


  _getvideoconfig(&video_config);

#define MAX_X video_config.numxpixels
#define MAX_Y video_config.numypixels


  { int x = MAX_X / 2,
        y = MAX_Y / 2,
        d = 0;
    int len;
    len = strlen(argv[1]);
    if (video_config.numcolors < len)
       { len = video_config.numcolors;
         argv[1][len] = '\0';
       }

    if (argc > 2)
       printf("%s", argv[1]);


    while (!kbhit())
      { int p = _getpixel(x,y);

        switch(argv[1][p])
        { case 'R' :
          case 'r' : d = (d + 3) % 4; break;
          case 'L' :
          case 'l' : d = (d + 1) % 4; break;
          case 'T' :
          case 't' : d = (d + 2) % 4; break;
        }

        _setcolor((p + 1) % len);
        _setpixel(x,y);

        switch (d)
        { case 0: x++; if (x >= MAX_X) x -= MAX_X; break;
          case 1: y++; if (y >= MAX_Y) y -= MAX_X; break;
          case 2: x--; if (x <  0)     x += MAX_X; break;
          case 3: y--; if (y <  0)     y += MAX_X; break;
        }
      }
  }
}