/////////////////////////////////////////////////////////////////////////
////                          PIC_PARSER.C                           ////
////                                                                 ////
////  This program shows how to implement a serial parser.           ////
////  Help and example code from the Circuit Cellar article:         ////
////  "Ham Radio Repeater Locator" - Glen Worstell                   ////
////  http://www.circuitcellar.com/library/print/0804/Worstell_169/  ////
////  Worstell-169.pdf                                               ////
////  Author : Gerard Sequeira                                       ////
///            Feb 27,2007                                           ////
/////////////////////////////////////////////////////////////////////////



#include <16F876A.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)  





char scar;             //current character on the serial port
char parse_needle;     //parser pointer in parseString
char dir_needle;       //direction pointer
char steer_needle;     //steering angle pointer
char speed_needle;     //speed pointer
const char parse_thread[]= "$dddtttsss";   //packet format
int16 dir;              //direction
int16 steer;            //steering
int16 speed;            //speed

void restart_parser(void)
{
   parse_needle   =  0;          //needle = pointer
   dir_needle     =  0;
   steer_needle   =  0;
   speed_needle   =  0;
   dir            =  0;
   steer          =  0;
   speed          =  0;
}



char is_digit()                  //check if incoming characters are digits
{
   if ((scar < '0') || (scar > '9')) return 0;
   else  return 1;
}

#int_rda
void parser_isr()
{
   static char parsechar;        //current parse character in parseString

   scar =  getc();               //dump RX char into serial_char

   if (scar == '$')
   {
      restart_parser();
      parse_needle++;
   }

   else
   {
      parsechar  =  parse_thread[parse_needle++];
      if (parsechar == 0) restart_parser();

      else
      {
         if ((parsechar >= 'a') && (parsechar <= 'z'))
            switch(parsechar)
            {
               case 'd' :
               if (!is_digit()) restart_parser();
               else dir = dir * 10 + (scar - '0');
               break;

               case 't' :
               if (!is_digit()) restart_parser();
               else steer = steer * 10 + (scar - '0');
               break;

               case 's' :
               if (!is_digit()) restart_parser();
               else speed = speed * 10 + (scar - '0');
               break;

               default :
               restart_parser();
            }
        else
        {
            if (scar != parsechar) restart_parser();
        }
      }
   }
}



void main()
{
      enable_interrupts(global);
      enable_interrupts(int_rda);
      output_high(PIN_B3);
      delay_ms(500);
      output_low(PIN_B3);
      delay_ms(500);
      output_high(PIN_B3);
      delay_ms(500);
      output_low(PIN_B3);
      delay_ms(500);

      restart_parser();                //initialise all values to zero

      while(1)
      {
       printf("Dir : %ld %ld %ld\n\r",dir,steer,speed);
      }


}