MySQL for the Internet of Things

Chapter 4 ■ Data transformation

*

• Returns integer - integer from the buffer
  /
  int read_int(byte buffer[], int offset, int size) {
  int value = 0;
  int new_size = 0;
  if (size == 0)
  new_size = get_lcb_len(offset);
  if (size == 1)
  return buffer[offset];
  new_size = size;
  int shifter = (new_size - 1) 8;
  for (int i = new_size; i > 0; i--) {
  value += (byte)(buffer[i-1] << shifter);
  shifter -= 8;
  }
  return value;
  }

/**

• store_int - Store an integer value into a byte array of size bytes.


• 
  


• This writes an integer into the buffer at the current position of the


• buffer. It will transform an integer of size to a length coded binary


• form where 1-3 bytes are used to store the value (set by size).


• 
  


• buff[in] pointer to location in internal buffer where the


• integer will be stored


• value[in] integer value to be stored


• size[in] number of bytes to use to store the integer
  /
  void store_int(byte buff, long value, int size) {
  memset(buff, 0, size);
  if (value < 0xff)
  buff[0] = (byte)value;
  else if (value < 0xffff) {
  buff[0] = (byte)value;
  buff[1] = (byte)(value >> 8);
  } else if (value < 0xffffff) {
  buff[0] = (byte)value;
  buff[1] = (byte)(value >> 8);
  buff[2] = (byte)(value >> 16);
  } else if (value < 0xffffff) {
  buff[0] = (byte)value;
  buff[1] = (byte)(value >> 8);
  buff[2] = (byte)(value >> 16);
  buff[3] = (byte)(value >> 24);
  }
  }