Package org.dellroad.stuff.io

Class BitwiseOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

org.dellroad.stuff.io.BitwiseOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class BitwiseOutputStream
extends FilterOutputStream

A bit-oriented OutputStream.

Instances support writing arbitrary numbers of individual bits. Bits are written to the underlying OutputStream in groups of eight (i.e., whole bytes, obviously), where the bits in each written byte are ordered from least significant to most significant bit.

Of course, instances also support writing traditional byte-oriented data: any bytes written are handled as if each of the eight bits were written individually, in order from least significant to most significant.

When instances are closed, if the output bitstream is not currently aligned to a byte boundary (i.e., bitOffset() would return a non-zero value), then padding of up to seven zero bits is written (as if by padToByteBoundary()), and then the underlying stream is closed.

As an example, writing the bits 0b101001101111 and then invoking close() would result in 0x6d 0x0e being written to the underlying stream. The same output would result if 0b111, 0x4d, and then 0b001 were written.

See Also:

• BitwiseInputStream

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor	Description
BitwiseOutputStream(OutputStream out)	Constructor.

Method Summary

Modifier and Type	Method	Description
int	bitOffset()	Get the current bit offset.
void	close()
int	padToByteBoundary()	Write zero bits to this output stream up to the next byte boundary.
void	write(byte[] buf, int off, int len)
void	write(int b)
void	writeBit(boolean bit)	Write a single bit.
void	writeBits(long bits, int len)	Write bits in a long value.
void	writeBits(BitSet bits, int len)	Write some bits from a BitSet.

Methods inherited from class java.io.FilterOutputStream

flush, write

Methods inherited from class java.io.OutputStream

nullOutputStream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

BitwiseOutputStream

public BitwiseOutputStream(OutputStream out)

Constructor.

Parameters:

out - underlying output

Method Details

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class FilterOutputStream

Throws:

IOException

write

public void write(byte[] buf,
 int off,
 int len)
           throws IOException

Overrides:

write in class FilterOutputStream

Throws:

IOException

write

public void write(int b)
           throws IOException

Overrides:

write in class FilterOutputStream

Throws:

IOException

writeBits

public void writeBits(BitSet bits,
 int len)
               throws IOException

Write some bits from a BitSet.

Parameters:

bits - where to get the bits

len - the number of bits to write

Throws:

IOException - if an I/O error occurs

IllegalArgumentException - if bits is null

IllegalArgumentException - if len is negative

writeBits

public void writeBits(long bits,
 int len)
               throws IOException

Write bits in a long value.

The first bit in bits written is at index zero, etc. Bits at index len and higher are ignored.

Parameters:

bits - value containing the bits to write (low-order bit first)

len - the number of bits in bits to write

Throws:

IOException - if an I/O error occurs

IllegalArgumentException - if len is negative or greater than 64

writeBit

public void writeBit(boolean bit)
              throws IOException

Write a single bit.

Parameters:

bit - the bit to write

Throws:

IOException - if an I/O error occurs

bitOffset

public int bitOffset()

Get the current bit offset.

Returns:

current bit offset (from zero to seven)

padToByteBoundary

public int padToByteBoundary()
                      throws IOException

Write zero bits to this output stream up to the next byte boundary.

If the number of bits written so far is a multiple of eight, this method does nothing. Otherwise it writes zero bits until the next write operation will be byte-aligned.

Returns:

the number of zero bits written (from zero to seven)

Throws:

IOException - if an I/O error occurs