org.at4j.support.io
Interface BitOutput

All Superinterfaces:

Closeable

All Known Implementing Classes:

LittleEndianBitOutputStream

public interface BitOutput
extends Closeable

This interface identifies a sink for bits.

The sink is assumed to have a position which may or may not be at a byte boundary (every eight bits).

If an implementing class also extends OutputStream it can be used as an output stream. This interface redefines OutputStream's write methods with the extra condition that they may only be used if the current position of the sink is at a byte boundary. The writeBytes(byte[], int, int) method does not have that limitation.

Since:

1.1

Author:

Karl Gustafsson

See Also:

OutputStream, BitInput

Method Summary

int	getNumberOfBitsInUnfinishedByte() Get the number of bits that have been written to the last byte.
int	getUnfinishedByte() Get the value of the unfinished byte.
void	padToByteBoundary() Pad the output with zeroes to the next byte boundary.
void	write(byte[] barr) See OutputStream.write(byte[]).
void	write(byte[] barr, int off, int len) See OutputStream.write(byte[], int, int).
void	write(int b) See OutputStream.write(int).
void	writeBit(boolean val) Write a single bit.
void	writeBits(int val, int no) Write up to eight bits.
void	writeBitsLittleEndian(int val, int no) Write up to 32 bits.
void	writeBytes(byte[] barr, int off, int len) Write an array of bytes to the output.

Methods inherited from interface java.io.Closeable

close

Method Detail

padToByteBoundary

void padToByteBoundary()
                       throws IOException

Pad the output with zeroes to the next byte boundary. If the current position is already at a byte boundary, this method does nothing.

Throws:

IOException - On I/O errors.

getUnfinishedByte

int getUnfinishedByte()

Get the value of the unfinished byte. The value is shifted so that the least significant bit positions are used. getNumberOfBitsInUnfinishedByte() returns how many bit positions that are used.

If the current position is at a byte boundary, 0 is returned.

Returns:

The value of the unfinished byte.

getNumberOfBitsInUnfinishedByte

int getNumberOfBitsInUnfinishedByte()

Get the number of bits that have been written to the last byte.

If the current position is at a byte boundary, 0 is returned.

Returns:

The number of bits that have been written to the last byte. This is a number between 0 and 7 (inclusive).

writeBit

void writeBit(boolean val)
              throws IOException

Write a single bit.

Parameters:

val - The bit (true == 1, false == 0).

Throws:

IOException - On I/O errors.

writeBits

void writeBits(int val,
               int no)
               throws IndexOutOfBoundsException,
                      IOException

Write up to eight bits.

Parameters:

val - The value to write. The bits written are the no rightmost bits of val. It is not verified that val fits within its no rightmost bits. If it does not, the written value is simply truncated.

no - The number of bits to write. This must be between 0 and 8 (inclusive).

Throws:

IndexOutOfBoundsException - If no is less than 0 or greater than 8.

IOException - On I/O errors

See Also:

writeBitsLittleEndian(int, int)

writeBitsLittleEndian

void writeBitsLittleEndian(int val,
                           int no)
                           throws IndexOutOfBoundsException,
                                  IOException

Write up to 32 bits. The bits are written little endian with the most significant bit first.

Parameters:

val - The value to write. The bits written are the no rightmost bits of val. It is not verified that val fits within its no rightmost bits. If it does not, the written value is simply truncated.

no - The number of bits to write. This must be between 0 and 32 (inclusive)

Throws:

IndexOutOfBoundsException - If no is less than 0 or more than 32.

IOException - On I/O errors.

See Also:

writeBits(int, int)

writeBytes

void writeBytes(byte[] barr,
                int off,
                int len)
                throws IndexOutOfBoundsException,
                       IOException

Write an array of bytes to the output. Unlike write(byte[], int, int), this method does not require that the current position is at a byte boundary.

Parameters:

barr - The bytes to write.

off - The offset in the byte array.

len - The number of bytes to write.

Throws:

IndexOutOfBoundsException - If the offset or the length is negative or if the offset + length is larger than the byte array.

IOException - On I/O errors

See Also:

write(byte[], int, int)

write

void write(int b)
           throws IOException

See OutputStream.write(int).

This method requires that the current position of the output is at a byte boundary.

Parameters:

b - The byte to write (0 - 255).

Throws:

IOException - On I/O errors or if the current position is not at a byte boundary.

See Also:

OutputStream.write(int)

write

void write(byte[] barr)
           throws IOException

See OutputStream.write(byte[]).

This method requires that the current position of the output is at a byte boundary.

Parameters:

barr - The bytes to write.

Throws:

IOException - On I/O errors or if the current position is not at a byte boundary.

See Also:

OutputStream.write(byte[])

write

void write(byte[] barr,
           int off,
           int len)
           throws IndexOutOfBoundsException,
                  IOException

See OutputStream.write(byte[], int, int).

This method requires that the current position of the output is at a byte boundary.

Parameters:

barr - The bytes to write.

off - The offset in the byte array.

len - The number of bytes to write.

Throws:

IndexOutOfBoundsException - If the offset or the length is negative or if the offset + length is larger than the byte array.

IOException - On I/O errors or if the current position is not at a byte boundary.

See Also:

OutputStream.write(byte[], int, int), writeBytes(byte[], int, int)