long readDWord() throws IOException {
  int b0=m_in.read();
  int b1=m_in.read();
  int b2=m_in.read();
  int b3=m_in.read();
  long value=((b3 << 24) & 0xff000000) | ((b2 << 16) & 0xff0000) | ((b1 << 8) & 0xff00)| (b0 & 0xff);
  return value;
}

long readDWord ( ) throws IOException { int b0 = m_in . read ( ) ; int b1 = m_in . read ( ) ; int b2 = m_in . read ( ) ; int b3 = m_in . read ( ) ; long value = ( ( b3 << 24 ) & 0xff000000 ) | ( ( b2 << 16 ) & 0xff0000 ) | ( ( b1 << 8 ) & 0xff00 ) | ( b0 & 0xff ) ; return value ; }
extract the next 4 bytes , which form a 32b integer , from the stream
