unsigned char bits = 0;  // the unwritten bits
int count = 0;  // the number of unwritten bits
 
// write_bit()
//    Write a single bit to the output stream
//
void write_bit( ostream& outs, bool bit )
  {
  // Add the latest bit into our "to-output" bits
  bits |= bit << count;
 
  // Track how many we have "output" so far
  if (++count < 8) return;
 
  // If we have "output" a whole byte, then
  // actually write it to the output stream
  outs.put( bits );
 
  // And reset
  bits  = 0;
  count = 0;
  }
 
// flush_bits()
//   Write any left-over bits --filling
//   with zeros to the even byte.
//
void flush_bits( ostream& outs )
  {
  if (count) outs.put( bits );
  bits  = 0;
  count = 0;
  }

  bit #   byte 1    byte 2
  1       .......@  ........
  2       ......@x  ........    These bytes are DISPLAYED
  3       .....@xx  ........    in the way that we humans
  4       ....@xxx  ........    like to read them, but what
  5       ...@xxxx  ........    is really IMPORTANT is that
  6       ..@xxxxx  ........    the bits fill in from the
  7       .@xxxxxx  ........    LEAST-significant bit to the
  8       @xxxxxxx  ........    MOST-significant bit in each byte.
  9       xxxxxxxx  .......@
  10      xxxxxxxx  ......@x