tv.danmaku.ijk.media.drm.util

Class ParsableBitArray

java.lang.Object

tv.danmaku.ijk.media.drm.util.ParsableBitArray

public final class ParsableBitArray
extends java.lang.Object

Wraps a byte array, providing methods that allow it to be read as a bitstream.

Field Summary

Fields

Modifier and Type	Field and Description
byte[]	data

Constructor Summary

Constructors

Constructor and Description
ParsableBitArray() Creates a new instance that initially has no backing data.
ParsableBitArray(byte[] data) Creates a new instance that wraps an existing array.
ParsableBitArray(byte[] data, int limit) Creates a new instance that wraps an existing array.

Method Summary

Modifier and Type	Method and Description
int	bitsLeft() Returns the number of bits yet to be read.
void	byteAlign() Aligns the position to the next byte boundary.
int	getBytePosition() Returns the current byte offset.
int	getPosition() Returns the current bit offset.
void	putInt(int value, int numBits) Overwrites numBits from this array using the numBits least significant bits from value.
boolean	readBit() Reads a single bit.
void	readBits(byte[] buffer, int offset, int numBits) Reads numBits bits into buffer.
int	readBits(int numBits) Reads up to 32 bits.
long	readBitsToLong(int numBits) Reads up to 64 bits.
void	readBytes(byte[] buffer, int offset, int length) Reads the next length bytes into buffer.
java.lang.String	readBytesAsString(int length) Reads the next length bytes as a UTF-8 string.
java.lang.String	readBytesAsString(int length, java.nio.charset.Charset charset) Reads the next length bytes as a string encoded in Charset.
void	reset(byte[] data) Updates the instance to wrap data, and resets the position to zero.
void	reset(byte[] data, int limit) Updates the instance to wrap data, and resets the position to zero.
void	reset(ParsableByteArray parsableByteArray) Sets this instance's data, position and limit to match the provided parsableByteArray.
void	setPosition(int position) Sets the current bit offset.
void	skipBit() Skips a single bit.
void	skipBits(int numBits) Skips bits and moves current reading position forward.
void	skipBytes(int length) Skips the next length bytes.

Methods inherited from class java.lang.Object

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

Field Detail

data

public byte[] data

Constructor Detail

ParsableBitArray

public ParsableBitArray()

Creates a new instance that initially has no backing data.

ParsableBitArray

public ParsableBitArray(byte[] data)

Creates a new instance that wraps an existing array.

Parameters:

data - The data to wrap.

ParsableBitArray

public ParsableBitArray(byte[] data,
                        int limit)

Creates a new instance that wraps an existing array.

Parameters:

data - The data to wrap.

limit - The limit in bytes.

Method Detail

reset

public void reset(byte[] data)

Updates the instance to wrap data, and resets the position to zero.

Parameters:

data - The array to wrap.

reset

public void reset(ParsableByteArray parsableByteArray)

Sets this instance's data, position and limit to match the provided parsableByteArray. Any modifications to the underlying data array will be visible in both instances

Parameters:

parsableByteArray - The ParsableByteArray.

reset

public void reset(byte[] data,
                  int limit)

Updates the instance to wrap data, and resets the position to zero.

Parameters:

data - The array to wrap.

limit - The limit in bytes.

bitsLeft

public int bitsLeft()

Returns the number of bits yet to be read.

getPosition

public int getPosition()

Returns the current bit offset.

getBytePosition

public int getBytePosition()

Returns the current byte offset. Must only be called when the position is byte aligned.

Throws:

java.lang.IllegalStateException - If the position isn't byte aligned.

setPosition

public void setPosition(int position)

Sets the current bit offset.

Parameters:

position - The position to set.

skipBit

public void skipBit()

Skips a single bit.

skipBits

public void skipBits(int numBits)

Skips bits and moves current reading position forward.

Parameters:

numBits - The number of bits to skip.

readBit

public boolean readBit()

Reads a single bit.

Returns:

Whether the bit is set.

readBits

public int readBits(int numBits)

Reads up to 32 bits.

Parameters:

numBits - The number of bits to read.

Returns:

An integer whose bottom numBits bits hold the read data.

readBitsToLong

public long readBitsToLong(int numBits)

Reads up to 64 bits.

Parameters:

numBits - The number of bits to read.

Returns:

A long whose bottom numBits bits hold the read data.

readBits

public void readBits(byte[] buffer,
                     int offset,
                     int numBits)

Reads numBits bits into buffer.

Parameters:

buffer - The array into which the read data should be written. The trailing numBits % 8 bits are written into the most significant bits of the last modified buffer byte. The remaining ones are unmodified.

offset - The offset in buffer at which the read data should be written.

numBits - The number of bits to read.

byteAlign

public void byteAlign()

Aligns the position to the next byte boundary. Does nothing if the position is already aligned.

readBytes

public void readBytes(byte[] buffer,
                      int offset,
                      int length)

Reads the next length bytes into buffer. Must only be called when the position is byte aligned.

Parameters:

buffer - The array into which the read data should be written.

offset - The offset in buffer at which the read data should be written.

length - The number of bytes to read.

Throws:

java.lang.IllegalStateException - If the position isn't byte aligned.

See Also:

System.arraycopy(Object, int, Object, int, int)

skipBytes

public void skipBytes(int length)

Skips the next length bytes. Must only be called when the position is byte aligned.

Parameters:

length - The number of bytes to read.

Throws:

java.lang.IllegalStateException - If the position isn't byte aligned.

readBytesAsString

public java.lang.String readBytesAsString(int length)

Reads the next length bytes as a UTF-8 string. Must only be called when the position is byte aligned.

Parameters:

length - The number of bytes to read.

Returns:

The string encoded by the bytes in UTF-8.

readBytesAsString

public java.lang.String readBytesAsString(int length,
                                          java.nio.charset.Charset charset)

Reads the next length bytes as a string encoded in Charset. Must only be called when the position is byte aligned.

Parameters:

length - The number of bytes to read.

charset - The character set of the encoded characters.

Returns:

The string encoded by the bytes in the specified character set.

putInt

public void putInt(int value,
                   int numBits)

Overwrites numBits from this array using the numBits least significant bits from value. Bits are written in order from most significant to least significant. The read position is advanced by numBits.

Parameters:

value - The integer whose numBits least significant bits are written into data.

numBits - The number of bits to write.