// int dec2int(char c) 
//
// Convert a character to its decimal equivalent.
//
// Inputs:
//   char c: a character to decode
//
// Return = the decimal value of character c
//        = -1 if the character is not a decimal character
//

int dec2int(char c) {
  if(c >= '0' && c <= '9') {
    // This is a valid character
    return(c-'0');
  }else return(-1);
};


// int get_dec(uint8_t num_digits)
//
// Read num_digits decimal digits from serial input (at most 4 digits).  Returns after that 
//  number of digits or after a non-decimal character has been read.  Always eats 
//  the one character following the number
//
// Inputs:
//    uint8_t num_digits: the maximum number of digits to read
//
// Return = the value that is read from the serial input
//        = 0 if the first character read from the serial input is non-decimal.
//

uint16_t get_dec(uint8_t num_digits)
{
  char c;
  uint16_t out = 0;
  int val;
  uint8_t counter;

  // Only accept at most 4 digits
  if(num_digits > 4)
    num_digits = 4;

  // Loop until we receive the max digits
  for(counter = 0; counter < num_digits; ++counter) {
    c = getchar();
    val = dec2int(c);
    if(val == -1)   {
      // We have hit the end of the integer: return our value
      return(out);
    }
    out = (out * 10) + val;
  };
  // We have read num_digits digits
  // Eat next char
  c = getchar();
  // Return parsed value
  return(out);
};