// Control robot movements by serial communication
// Notice the arrangement of keys on the PC numeric pad

#include "motor.h"

main()
{
   int    x;

   writes("comm", 500);
   setcomm(9600);
   loop {
        do x = readm(232, 0); while(x == -1);  // wait to receive a character
      writec(0, x, 10);
      writec(232, x, 0);
      switch(x) {
      case '8': drive( 1,  1, 0); break;  // forward
      case '7': drive(-1,  1, 0); break;  // spin left
      case '9': drive( 1, -1, 0); break;  // spin right
      case '2': drive(-1, -1, 0); break;  // backward
      case '4': turn_left();      break; 
      case '6': turn_right();     break; 
      case '5': stop_all();       break; 
      case '0': stop_all(); writes("end", 2000); exit(); break;  // stop and exit
      }
   }
}

turn_left()
{
   drive(-1, -1, 500); // backward
   drive(-1,  1, 500); // turn left
}

turn_right()
{
   drive(-1, -1, 500); // backward
   drive( 1, -1, 500); // turn right
}