de.carne.nio.compression.common

Class BitDecoder

java.lang.Object

de.carne.nio.compression.common.BitDecoder

public final class BitDecoder
extends java.lang.Object

Utility class providing bit-level access to a ReadableByteChannel's data.

The actual bit access is done via a BitRegister instance. Multiple bit registers can be used in parallel.

Constructor Summary

Constructors

Constructor and Description
BitDecoder(BitRegister[] registers) Construct BitDecoder.
BitDecoder(BitRegister[] registers, byte... trailingBytes) Construct BitDecoder.

Method Summary

Modifier and Type	Method and Description
void	alignToByte() Make sure the next decode or read action is byte-aligned.
void	clear() Clear all pending bits.
int	decodeBits(java.nio.channels.ReadableByteChannel src, int count) Decode a number of bits from the source channel and discard them.
int	decodeBits(java.nio.channels.ReadableByteChannel src, int count, int registerIndex) Decode a number of bits from the source channel and discard them.
int	peekBits(java.nio.channels.ReadableByteChannel src, int count) Decode a number of bits from the source channel without discarding them.
int	peekBits(java.nio.channels.ReadableByteChannel src, int count, int registerIndex) Decode a number of bits from the source channel without discarding them.
int	readByte(java.nio.channels.ReadableByteChannel src) Perform a direct byte-aligned read of a single byte and discard the corresponding bits.
int	readBytes(java.nio.channels.ReadableByteChannel src, java.nio.ByteBuffer dst) Perform a direct byte-aligned read and discard the corresponding bits.
void	reset() Reset the decoder to it's initial state.
long	totalIn() Get the total number of decoded bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

BitDecoder

public BitDecoder(BitRegister[] registers)

Construct BitDecoder.

Parameters:

registers - The bit registers to use.

BitDecoder

public BitDecoder(BitRegister[] registers,
                  byte... trailingBytes)

Construct BitDecoder.

Parameters:

registers - The bit registers to use.

trailingBytes - The optional bytes to feed after the underlying reader has reached EOF.

Method Detail

reset

public void reset()

Reset the decoder to it's initial state.

clear

public void clear()

Clear all pending bits.

totalIn

public long totalIn()

Get the total number of decoded bytes.

Returns:

The total number of decoded bytes.

peekBits

public int peekBits(java.nio.channels.ReadableByteChannel src,
                    int count)
             throws java.io.IOException

Decode a number of bits from the source channel without discarding them.

This function uses the register 0 for bit decoding.

Parameters:

src - The source channel to decode from.

count - The number of bits to decode.

Returns:

The decoded bits.

Throws:

java.io.IOException - if an I/O error occurs.

peekBits

public int peekBits(java.nio.channels.ReadableByteChannel src,
                    int count,
                    int registerIndex)
             throws java.io.IOException

Decode a number of bits from the source channel without discarding them.

Parameters:

src - The source channel to decode from.

count - The number of bits to decode.

registerIndex - The register to use for bit decoding.

Returns:

The decoded bits.

Throws:

java.io.IOException - if an I/O error occurs.

decodeBits

public int decodeBits(java.nio.channels.ReadableByteChannel src,
                      int count)
               throws java.io.IOException

Decode a number of bits from the source channel and discard them.

This function uses the register 0 for bit decoding.

Parameters:

src - The source channel to decode from.

count - The number of bits to decode.

Returns:

The decoded bits.

Throws:

java.io.IOException - if an I/O error occurs.

decodeBits

public int decodeBits(java.nio.channels.ReadableByteChannel src,
                      int count,
                      int registerIndex)
               throws java.io.IOException

Decode a number of bits from the source channel and discard them.

Parameters:

src - The source channel to decode from.

count - The number of bits to decode.

registerIndex - The register to use for bit decoding.

Returns:

The decoded bits.

Throws:

java.io.IOException - if an I/O error occurs.

alignToByte

public void alignToByte()

Make sure the next decode or read action is byte-aligned.

readBytes

public int readBytes(java.nio.channels.ReadableByteChannel src,
                     java.nio.ByteBuffer dst)
              throws java.io.IOException

Perform a direct byte-aligned read and discard the corresponding bits.

This function allows optimized access bulk reading data.

Parameters:

src - The source channel to read from.

dst - The ByteBuffer to read into.

Returns:

The number of read bytes or -1 if the channel reached end-of-stream.

Throws:

java.io.IOException - if an I/O error occurs.

readByte

public int readByte(java.nio.channels.ReadableByteChannel src)
             throws java.io.IOException

Perform a direct byte-aligned read of a single byte and discard the corresponding bits.

Parameters:

src - The source channel to read from.

Returns:

The read byte -1 if the channel reached end-of-stream.

Throws:

java.io.IOException - if an I/O error occurs.