org.apache.commons.compress.utils

Class BitInputStream

java.lang.Object

org.apache.commons.compress.utils.BitInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

Direct Known Subclasses:

BitStream

public class BitInputStream
extends java.lang.Object
implements java.io.Closeable

Reads bits from an InputStream.

Since:

1.10

Field Summary

Fields

Modifier and Type	Field and Description
private long	bitsCached
private int	bitsCachedSize
private java.nio.ByteOrder	byteOrder
private java.io.InputStream	in
private static long[]	MASKS
private static int	MAXIMUM_CACHE_SIZE

Constructor Summary

Constructors

Constructor and Description
BitInputStream(java.io.InputStream in, java.nio.ByteOrder byteOrder) Constructor taking an InputStream and its bit arrangement.

Method Summary

Modifier and Type	Method and Description
void	clearBitCache() Clears the cache of bits that have been read from the underlying stream but not yet provided via readBits(int).
void	close()
private boolean	ensureCache(int count) Fills the cache up to 56 bits
private long	processBitsGreater57(int count)
long	readBits(int count) Returns at most 63 bits read from the underlying stream.

Methods inherited from class java.lang.Object

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

Field Detail

MAXIMUM_CACHE_SIZE

private static final int MAXIMUM_CACHE_SIZE

See Also:

Constant Field Values

MASKS

private static final long[] MASKS

in

private final java.io.InputStream in

byteOrder

private final java.nio.ByteOrder byteOrder

bitsCached

private long bitsCached

bitsCachedSize

private int bitsCachedSize

Constructor Detail

BitInputStream

public BitInputStream(java.io.InputStream in,
                      java.nio.ByteOrder byteOrder)

Constructor taking an InputStream and its bit arrangement.

Parameters:

in - the InputStream

byteOrder - the bit arrangement across byte boundaries, either BIG_ENDIAN (aaaaabbb bb000000) or LITTLE_ENDIAN (bbbaaaaa 000000bb)

Method Detail

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException

clearBitCache

public void clearBitCache()

Clears the cache of bits that have been read from the underlying stream but not yet provided via readBits(int).

readBits

public long readBits(int count)
              throws java.io.IOException

Returns at most 63 bits read from the underlying stream.

Parameters:

count - the number of bits to read, must be a positive number not bigger than 63.

Returns:

the bits concatenated as a long using the stream's byte order. -1 if the end of the underlying stream has been reached before reading the requested number of bits

Throws:

java.io.IOException - on error

processBitsGreater57

private long processBitsGreater57(int count)
                           throws java.io.IOException

Throws:

java.io.IOException

ensureCache

private boolean ensureCache(int count)
                     throws java.io.IOException

Fills the cache up to 56 bits

Parameters:

count -

Returns:

return true, when EOF

Throws:

java.io.IOException