Utilities - Data Structures and Problem Solving Using Java - page 482

1 // BitOutputStream class: Bit-output stream wrapper class.
2 //
3 // CONSTRUCTION: with an open OutputStream.
4 //
5 // ******************PUBLIC OPERATIONS***********************
6 // void writeBit( val ) --> Write one bit (0 or 1)
7 // void writeBits( vals ) --> Write array of bits
8 // void flush( ) --> Flush buffered bits
9 // void close( ) --> Close underlying stream
10
11 public class BitOutputStream
12 {
13 public BitOutputStream( OutputStream os )
14 { bufferPos = 0; buffer = 0; out = os; }
15
16 public void writeBit( int val ) throws IOException
17 {
18 buffer = setBit( buffer, bufferPos++, val );
19 if( bufferPos == BitUtils.BITS_PER_BYTES )
20 flush( );
21 }
22
23 public void writeBits( int [ ] val ) throws IOException
24 {
25 for( int i = 0; i < val.length; i++ )
26 writeBit( val[ i ] );
27 }
28
29 public void flush( ) throws IOException
30 {
31 if( bufferPos == 0 )
32 return;
33 out.write( buffer );
34 bufferPos = 0;
35 buffer = 0;
36 }
37
38 public void close( ) throws IOException
39 { flush( ); out.close( ); }
40
41 private int setBit( int pack, int pos, int val )
42 {
43 if( val == 1 )
44 pack |= ( val << pos );
45 return pack;
46 }
47
48 private OutputStream out;
49 private int buffer;
50 private int bufferPos;
51 }

figure 12.15
The BitOutputStream
class