InputBitStream (dsiutil 2.0.5)

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it.unimi.dsi.io
Class InputBitStream

java.lang.Object
  it.unimi.dsi.fastutil.booleans.AbstractBooleanIterator
      it.unimi.dsi.io.InputBitStream

All Implemented Interfaces:: BooleanIterator, Closeable, Flushable, Iterator<Boolean>

Direct Known Subclasses:: DebugInputBitStream

public class InputBitStream
extends AbstractBooleanIterator
implements Flushable, Closeable
extends AbstractBooleanIterator
implements Flushable, Closeable

Bit-level input stream.

This class wraps any InputStream so that you can treat it as bit stream. Constructors and methods closely resemble those of InputStream. Data can be read from such a stream in several ways: reading an integer or long in fixed-width, unary, γ, shifted γ, δ, ζ and (skewed) Golomb coding, or reading a number of bits that will be stored in a vector of bytes. There is limited support for mark(int)/reset() operations.

This class can also wrap a byte array; this is much more lightweight than wrapping a FastByteArrayInputStream wrapping the array. Overflowing the array will cause an EOFException.

Note that when reading using a vector of bytes bits are read in the stream format (see OutputBitStream): the first bit is bit 7 of the first byte, the eighth bit is bit 0 of the first byte, the ninth bit is bit 7 of the second byte and so on. When reading integers using some coding, instead, they are stored in the standard way, that is, in the lower bits.

Additional features:

This class provides an internal buffer. By setting a buffer of length 0 at creation time, you can actually bypass the buffering system: Note, however, that several classes providing buffering have synchronised methods, so using a wrapper instead of the internal buffer is likely to lead to a performance drop.
To work around the schizophrenic relationship between streams and random access files in java.io, this class provides a flush() method that resets the internal state. At this point, you can safely reposition the underlying stream and read again afterwards. For instance, this is safe and will perform as expected:
```
 FileInputStream fis = new FileInputStream( ... );
 InputBitStream ibs = new InputBitStream( fis );
 ... read operations on ibs ...
 ibs.flush();
 fis.getChannel().position( ... );
 ... other read operations on ibs ...
 
```
As a commodity, an instance of this class will try to cast the underlying byte stream to a RepositionableStream and to fetch by reflection the FileChannel underlying the given input stream, in this order. If either reference can be successfully fetched, you can use directly the position() method with argument pos with the same semantics of a flush(), followed by a call to position(pos / 8) (where the latter method belongs either to the underlying stream or to its underlying file channel), followed by a skip(pos % 8). However, since the reflective checks are quite heavy they can be disabled using a suitable constructor.
Finally, this class implements partially the interface of a boolean iterator. More precisely, nextBoolean() will return the same bit as readBit(), and also the same exceptions, whereas hasNext() will always return true: you must be prepared to catch a RuntimeException wrapping an IOException in case the file ends. It is very difficult to implement completely an eager operator using a input-stream based model.

This class is not synchronised. If multiple threads access an instance of this class concurrently, they must be synchronised externally.

Since:: 0.1
Author:: Sebastiano Vigna
See Also:: InputStream, OutputBitStream

Field Summary
`protected int`	`avail` Current number of bytes available in the byte buffer.
`protected byte[]`	`buffer` The stream buffer.
`static int`	`DEFAULT_BUFFER_SIZE` The default size of the byte buffer in bytes (8Ki).
`static int[]`	`DELTA`
`protected FileChannel`	`fileChannel` The cached file channel underlying `is`, if any.
`protected int`	`fill` Current number of bits in the bit buffer (stored low).
`static int[]`	`GAMMA`
`protected InputStream`	`is` The underlying `InputStream`.
`protected int`	`pos` Current position in the byte buffer.
`protected long`	`position` Current position of the first byte in the byte buffer.
`protected RepositionableStream`	`repositionableStream` `is` cast to a positionable stream, if possible.
`static int[]`	`SHIFTED_GAMMA`
`protected boolean`	`wrapping` True if we are wrapping an array.
`static int[]`	`ZETA_3`

Constructor Summary
`protected`	`InputBitStream()` This (non-public) constructor exists just to provide fake initialisation for classes such as `DebugInputBitStream`.
	`InputBitStream(byte[] a)` Creates a new input bit stream wrapping a given byte array.
	`InputBitStream(File file)` Creates a new input bit stream reading from a file.
	`InputBitStream(FileInputStream is)` Creates a new input bit stream wrapping a given file input stream using a buffer of size `DEFAULT_BUFFER_SIZE`.
	`InputBitStream(FileInputStream is, int bufSize)` Creates a new input bit stream wrapping a given file input stream with a specified buffer size.
	`InputBitStream(File file, int bufSize)` Creates a new input bit stream reading from a file.
	`InputBitStream(InputStream is)` Creates a new input bit stream wrapping a given input stream using a buffer of size `DEFAULT_BUFFER_SIZE`.
	`InputBitStream(InputStream is, boolean testForPosition)` Creates a new input bit stream wrapping a given input stream using a buffer of size `DEFAULT_BUFFER_SIZE`.
	`InputBitStream(InputStream is, int bufSize)` Creates a new input bit stream wrapping a given input stream with a specified buffer size.
	`InputBitStream(InputStream is, int bufSize, boolean testForPosition)` Creates a new input bit stream wrapping a given input stream with a specified buffer size.
	`InputBitStream(String name)` Creates a new input bit stream reading from a file.
	`InputBitStream(String name, int bufSize)` Creates a new input bit stream reading from a file.

Method Summary
`void`	`align()` Aligns the stream.
`long`	`available()` Returns the number of bits that can be read (or skipped over) from this bit stream without blocking by the next caller of a method.
`void`	`close()` Closes the bit stream.
`void`	`flush()` Flushes the bit stream.
`boolean`	`hasNext()`
`void`	`mark(int readLimit)` Marks the current position in this input stream.
`boolean`	`markSupported()` Tests if this stream supports the `mark(int)` and `reset()` methods.
`boolean`	`nextBoolean()`
`void`	`position(long position)` Sets this stream bit position, if it is based on a `RepositionableStream` or on a `FileChannel`.
`void`	`read(byte[] bits, int len)` Reads a sequence of bits.
`int`	`readBit()` Reads a bit.
`long`	`readBits()` Returns the number of bits read from this bit stream.
`void`	`readBits(long readBits)` Sets the number of bits read from this bit stream.
`int`	`readDelta()` Reads a natural number in δ coding.
`void`	`readDeltas(int[] a, int count)` Reads a given number of δ-coded integers.
`int`	`readGamma()` Reads a natural number in γ coding.
`void`	`readGammas(int[] a, int count)` Reads a given number of γ-coded integers.
`int`	`readGolomb(int b)` Reads a natural number in Golomb coding.
`int`	`readGolomb(int b, int log2b)` Reads a natural number in Golomb coding.
`int`	`readInt(int len)` Reads a fixed number of bits into an integer.
`long`	`readLong(int len)` Reads a fixed number of bits into a long.
`long`	`readLongDelta()` Reads a long natural number in δ coding.
`long`	`readLongGamma()` Reads a long natural number in γ coding.
`long`	`readLongGolomb(long b)` Reads a long natural number in Golomb coding.
`long`	`readLongGolomb(long b, int log2b)` Reads a long natural number in Golomb coding.
`long`	`readLongMinimalBinary(long b)` Reads a long natural number in a limited range using a minimal binary coding.
`long`	`readLongMinimalBinary(long b, int log2b)` Reads a long natural number in a limited range using a minimal binary coding.
`long`	`readLongNibble()` Reads a long natural number in variable-length nibble coding.
`long`	`readLongShiftedGamma()` Reads a natural number in shifted γ coding.
`long`	`readLongSkewedGolomb(long b)` Reads a long natural number in skewed Golomb coding.
`long`	`readLongUnary()` Reads a long natural number in unary coding.
`long`	`readLongZeta(int k)` Reads a long natural number in ζ coding.
`int`	`readMinimalBinary(int b)` Reads a natural number in a limited range using a minimal binary coding.
`int`	`readMinimalBinary(int b, int log2b)` Reads a natural number in a limited range using a minimal binary coding.
`int`	`readNibble()` Reads a natural number in variable-length nibble coding.
`int`	`readShiftedGamma()` Reads a natural number in shifted γ coding.
`void`	`readShiftedGammas(int[] a, int count)` Reads a given number of shifted-γ-coded integers.
`int`	`readSkewedGolomb(int b)` Reads a natural number in skewed Golomb coding.
`int`	`readUnary()` Reads a natural number in unary coding.
`int`	`readZeta(int k)` Reads a natural number in ζ coding.
`void`	`readZetas(int k, int[] a, int count)` Reads a given number of γ-coded integers.
`void`	`reset()` Repositions this bit stream to the position at the time the `mark(int)` method was last called.
`int`	`skip(int n)` Deprecated. This method is simply an expensive, try/catch-surrounded version of `skip(long)` that is made necessary by the interface by `BooleanIterator`.
`long`	`skip(long n)` Skips the given number of bits.
`void`	`skipDeltas(int n)` Skips a given number of δ-coded integers.
`void`	`skipDeltas(long n)` Skips a given number of δ-coded integers.
`void`	`skipGammas(int n)` Skips a given number of γ-coded integers.
`void`	`skipGammas(long n)` Skips a given number of γ-coded integers.
`void`	`skipShiftedGammas(int n)` Skips a given number of shited-γ-coded integers.
`void`	`skipShiftedGammas(long n)` Skips a given number of shited-γ-coded integers.
`void`	`skipZetas(int k, int n)` Skips a given number of ζ-coded integers.
`void`	`skipZetas(int k, long n)` Skips a given number of ζ-coded integers.

Methods inherited from class it.unimi.dsi.fastutil.booleans.AbstractBooleanIterator
`next, remove`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

GAMMA

public static final int[] GAMMA

DELTA

public static final int[] DELTA

ZETA_3

public static final int[] ZETA_3

SHIFTED_GAMMA

public static final int[] SHIFTED_GAMMA

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE

The default size of the byte buffer in bytes (8Ki).

See Also:: Constant Field Values

is

protected final InputStream is

The underlying InputStream.

fileChannel

protected final FileChannel fileChannel

The cached file channel underlying is, if any.

repositionableStream

protected final RepositionableStream repositionableStream

is cast to a positionable stream, if possible.

wrapping

protected final boolean wrapping

True if we are wrapping an array.

buffer

protected byte[] buffer

The stream buffer.

fill

protected int fill

Current number of bits in the bit buffer (stored low).

pos

protected int pos

Current position in the byte buffer.

avail

protected int avail

Current number of bytes available in the byte buffer.

position

protected long position

Current position of the first byte in the byte buffer.

Constructor Detail

InputBitStream

protected InputBitStream()

This (non-public) constructor exists just to provide fake initialisation for classes such as DebugInputBitStream.

InputBitStream

public InputBitStream(InputStream is)

Creates a new input bit stream wrapping a given input stream using a buffer of size DEFAULT_BUFFER_SIZE.

This constructor performs the reflective tests that are necessary to support position(long).

Parameters:: is - the input stream to wrap.

InputBitStream

public InputBitStream(InputStream is,
                      boolean testForPosition)

Creates a new input bit stream wrapping a given input stream using a buffer of size DEFAULT_BUFFER_SIZE.

Parameters:: is - the input stream to wrap.; testForPosition - if false, the reflective test that is necessary to support position(long) in case is does not implement RepositionableStream will not be performed.

InputBitStream

public InputBitStream(InputStream is,
                      int bufSize)

Creates a new input bit stream wrapping a given input stream with a specified buffer size.

This constructor performs the reflective tests that are necessary to support position(long).

Parameters:: is - the input stream to wrap.; bufSize - the size in byte of the buffer; it may be 0, denoting no buffering.

InputBitStream

public InputBitStream(InputStream is,
                      int bufSize,
                      boolean testForPosition)

Creates a new input bit stream wrapping a given input stream with a specified buffer size.

Parameters:: is - the input stream to wrap.; bufSize - the size in byte of the buffer; it may be 0, denoting no buffering.; testForPosition - if false, the reflective test that is necessary to support position(long) in case is does not implement RepositionableStream will not be performed.

InputBitStream

public InputBitStream(FileInputStream is)

Creates a new input bit stream wrapping a given file input stream using a buffer of size DEFAULT_BUFFER_SIZE.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: is - the file input stream to wrap.

InputBitStream

public InputBitStream(FileInputStream is,
                      int bufSize)

Creates a new input bit stream wrapping a given file input stream with a specified buffer size.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: is - the file input stream to wrap.; bufSize - the size in byte of the buffer; it may be 0, denoting no buffering.

InputBitStream

public InputBitStream(byte[] a)

Creates a new input bit stream wrapping a given byte array.

Parameters:: a - the byte array to wrap.

InputBitStream

public InputBitStream(String name,
                      int bufSize)
               throws FileNotFoundException

Creates a new input bit stream reading from a file.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: name - the name of the file.; bufSize - the size in byte of the buffer; it may be 0, denoting no buffering.
Throws:: FileNotFoundException

InputBitStream

public InputBitStream(String name)
               throws FileNotFoundException

Creates a new input bit stream reading from a file.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: name - the name of the file.
Throws:: FileNotFoundException

InputBitStream

public InputBitStream(File file)
               throws FileNotFoundException

Creates a new input bit stream reading from a file.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: file - the file.
Throws:: FileNotFoundException

InputBitStream

public InputBitStream(File file,
                      int bufSize)
               throws FileNotFoundException

Creates a new input bit stream reading from a file.

This constructor invokes directly FileInputStream.getChannel() to support position(long).

Parameters:: file - the file.; bufSize - the size in byte of the buffer; it may be 0, denoting no buffering.
Throws:: FileNotFoundException

Method Detail

flush

public void flush()

Flushes the bit stream. All state information associated with the stream is reset. This includes bytes prefetched from the stream, bits in the bit buffer and unget'd bits.

This method is provided so that users of this class can easily wrap repositionable streams (for instance, file-based streams, which can be repositioned using the underlying FileChannel). It is guaranteed that after calling this method the underlying stream can be repositioned, and that the next read will draw data from the stream.

Specified by:: flush in interface Flushable

close

public void close()
           throws IOException

Closes the bit stream. All resources associated with the stream are released.

Specified by:: close in interface Closeable

Throws:: IOException

available

public long available()
               throws IOException

Returns the number of bits that can be read (or skipped over) from this bit stream without blocking by the next caller of a method.

Returns:: the number of bits that can be read from this bit stream without blocking.
Throws:: IOException

readBits

public long readBits()

Returns the number of bits read from this bit stream.

Returns:: the number of bits read so far.

readBits

public void readBits(long readBits)

Sets the number of bits read from this bit stream.

This method is provided so that, for instance, the user can reset via readBits(0) the read-bits count after a flush().

Parameters:: readBits - the new value for the number of bits read so far.

align

public void align()

Aligns the stream. After a call to this function, the stream is byte aligned. Bits that have been read to align are discarded.

read

public void read(byte[] bits,
                 int len)
          throws IOException

Reads a sequence of bits. Bits will be read in the natural way: the first bit is bit 7 of the first byte, the eightth bit is bit 0 of the first byte, the ninth bit is bit 7 of the second byte and so on.

Parameters:: bits - an array of bytes to store the result.; len - the number of bits to read.
Throws:: IOException

readBit

public int readBit()
            throws IOException

Reads a bit.

Returns:: the next bit from the stream.
Throws:: IOException

readInt

public int readInt(int len)
            throws IOException

Reads a fixed number of bits into an integer.

Parameters:: len - a bit length.
Returns:: an integer whose lower len bits are taken from the stream; the rest is zeroed.
Throws:: IOException

readLong

public long readLong(int len)
              throws IOException

Reads a fixed number of bits into a long.

Parameters:: len - a bit length.
Returns:: a long whose lower len bits are taken from the stream; the rest is zeroed.
Throws:: IOException

skip

public long skip(long n)
          throws IOException

Skips the given number of bits.

Parameters:: n - the number of bits to skip.
Returns:: the actual number of skipped bits.
Throws:: IOException

position

public void position(long position)
              throws IOException

Sets this stream bit position, if it is based on a RepositionableStream or on a FileChannel.

Given an underlying stream that implements RepositionableStream or that can provide a FileChannel via the getChannel() method, a call to this method has the same semantics of a flush(), followed by a call to position(position / 8) on the byte stream, followed by a skip(position % 8).

Note that this method does not change the value returned by readBits().

Parameters:: position - the new position expressed as a bit offset.
Throws:: UnsupportedOperationException - if the underlying byte stream does not implement RepositionableStream or if the channel it returns is not a FileChannel.; IOException
See Also:: FileChannel.position(long)

markSupported

public boolean markSupported()

Tests if this stream supports the mark(int) and reset() methods.

This method will just delegate the test to the underlying InputStream.

Returns:: whether this stream supports mark(int)/reset().

mark

public void mark(int readLimit)
          throws IOException

Marks the current position in this input stream. A subsequent call to the reset() method repositions this stream at the last marked position so that subsequent reads re-read the same bits.

This method will just delegate the mark to the underlying InputStream. Moreover, it will throw an exception if you try to mark outsite byte boundaries.

Parameters:: readLimit - the maximum limit of bytes that can be read before the mark position becomes invalid.
Throws:: IOException - if you try to mark outside byte boundaries.

reset

public void reset()
           throws IOException

Repositions this bit stream to the position at the time the mark(int) method was last called.

This method will just flush the stream and delegate the reset to the underlying InputStream.

Throws:: IOException

readUnary

public int readUnary()
              throws IOException

Reads a natural number in unary coding.

Returns:: the next unary-encoded natural number.
Throws:: IOException
See Also:: OutputBitStream.writeUnary(int)

readLongUnary

public long readLongUnary()
                   throws IOException

Reads a long natural number in unary coding. Note that by unary coding we mean that 1 encodes 0, 01 encodes 1 and so on.

Returns:: the next unary-encoded long natural number.
Throws:: IOException
See Also:: OutputBitStream.writeUnary(int)

readGamma

public int readGamma()
              throws IOException

Reads a natural number in γ coding.

Returns:: the next γ-encoded natural number.
Throws:: IOException
See Also:: OutputBitStream.writeGamma(int), skipGammas(int)

readLongGamma

public long readLongGamma()
                   throws IOException

Reads a long natural number in γ coding.

Returns:: the next γ-encoded long natural number.
Throws:: IOException
See Also:: OutputBitStream.writeGamma(int), skipGammas(int)

skipGammas

public void skipGammas(long n)
                throws IOException

Skips a given number of γ-coded integers.

This method should be significantly quicker than iterating n times on readGamma() or readLongGamma(), as precomputed tables are used directly, so the number of method calls is greatly reduced, and the result is discarded, so skip(long) can be invoked instead of more specific decoding methods.

Parameters:: n - the number of γ-coded integers to be skipped.
Throws:: IOException
See Also:: readGamma()

skipGammas

public void skipGammas(int n)
                throws IOException

Skips a given number of γ-coded integers.

Parameters:: n - the number of γ-coded integers to be skipped.
Throws:: IOException
See Also:: readGamma()

readGammas

public void readGammas(int[] a,
                       int count)
                throws IOException

Reads a given number of γ-coded integers.

This method should be significantly quicker than iterating n times on readGamma(), as precomputed tables are used directly, so the number of method calls is greatly reduced.

Parameters:: a - an array of at least count integers where the result wil be written starting at the first position.; count - the number of γ-coded integers to be read.
Throws:: IOException
See Also:: readGamma()

readShiftedGamma

public int readShiftedGamma()
                     throws IOException

Reads a natural number in shifted γ coding.

Returns:: the next shifted-γ–encoded natural number.
Throws:: IOException
See Also:: OutputBitStream.writeShiftedGamma(int), skipShiftedGammas(int)

readLongShiftedGamma

public long readLongShiftedGamma()
                          throws IOException

Reads a natural number in shifted γ coding.

Returns:: the next shifted-γ–encoded natural number.
Throws:: IOException
See Also:: OutputBitStream.writeShiftedGamma(int), skipShiftedGammas(int)

skipShiftedGammas

public void skipShiftedGammas(long n)
                       throws IOException

Skips a given number of shited-γ-coded integers.

This method should be significantly quicker than iterating n times on readShiftedGamma() or readLongShiftedGamma(), as precomputed tables are used directly, so the number of method calls is greatly reduced, and the result is discarded, so skip(long) can be invoked instead of more specific decoding methods.

Parameters:: n - the number of shited-γ-coded integers to be skipped.
Throws:: IOException
See Also:: readShiftedGamma()

skipShiftedGammas

public void skipShiftedGammas(int n)
                       throws IOException

Skips a given number of shited-γ-coded integers.

Parameters:: n - the number of shited-γ-coded integers to be skipped.
Throws:: IOException
See Also:: readShiftedGamma()

readShiftedGammas

public void readShiftedGammas(int[] a,
                              int count)
                       throws IOException

Reads a given number of shifted-γ-coded integers.

This method should be significantly quicker than iterating n times on readShiftedGamma(), as precomputed tables are used directly, so the number of method calls is greatly reduced.

Parameters:: a - an array of at least count integers where the result wil be written starting at the first position.; count - the number of shifted-γ-coded integers to be read.
Throws:: IOException
See Also:: readShiftedGamma()

readDelta

public int readDelta()
              throws IOException

Reads a natural number in δ coding.

Returns:: the next δ-encoded natural number.
Throws:: IOException
See Also:: OutputBitStream.writeDelta(int), skipDeltas(int)

readLongDelta

public long readLongDelta()
                   throws IOException

Reads a long natural number in δ coding.

Returns:: the next δ-encoded long natural number.
Throws:: IOException
See Also:: OutputBitStream.writeDelta(int), skipDeltas(int)

skipDeltas

public void skipDeltas(long n)
                throws IOException

Skips a given number of δ-coded integers.

This method should be significantly quicker than iterating n times on readDelta() or readLongDelta(), as precomputed tables are used directly, so the number of method calls is greatly reduced, and the result is discarded, so skip(long) can be invoked instead of more specific decoding methods.

Parameters:: n - the number of δ-coded integers to be skipped.
Throws:: IOException
See Also:: readDelta()

skipDeltas

public void skipDeltas(int n)
                throws IOException

Skips a given number of δ-coded integers.

Parameters:: n - the number of δ-coded integers to be skipped.
Throws:: IOException
See Also:: readDelta()

readDeltas

public void readDeltas(int[] a,
                       int count)
                throws IOException

Reads a given number of δ-coded integers.

This method should be significantly quicker than iterating n times on readDelta(), as precomputed tables are used directly, so the number of method calls is greatly reduced.

Parameters:: a - an array of at least count integers where the result wil be written starting at the first position.; count - the number of δ-coded integers to be read.
Throws:: IOException
See Also:: readDelta()

readMinimalBinary

public int readMinimalBinary(int b)
                      throws IOException

Reads a natural number in a limited range using a minimal binary coding.

Parameters:: b - a strict upper bound.
Returns:: the next minimally binary encoded natural number.
Throws:: IllegalArgumentException - if you try to read a negative number or use a nonpositive base.; IOException
See Also:: OutputBitStream.writeMinimalBinary(int, int)

readMinimalBinary

public int readMinimalBinary(int b,
                             int log2b)
                      throws IOException

Reads a natural number in a limited range using a minimal binary coding. This method is faster than readMinimalBinary(int) because it does not have to compute log2b.

Parameters:: b - a strict upper bound.; log2b - the floor of the base-2 logarithm of the bound.
Returns:: the next minimally binary encoded natural number.
Throws:: IllegalArgumentException - if you try to read a negative number or use a nonpositive base.; IOException
See Also:: OutputBitStream.writeMinimalBinary(int, int)

readLongMinimalBinary

public long readLongMinimalBinary(long b)
                           throws IOException

Reads a long natural number in a limited range using a minimal binary coding.

Parameters:: b - a strict upper bound.
Returns:: the next minimally binary encoded long natural number.
Throws:: IllegalArgumentException - if you try to read a negative number or use a nonpositive base.; IOException
See Also:: OutputBitStream.writeMinimalBinary(int, int)

readLongMinimalBinary

public long readLongMinimalBinary(long b,
                                  int log2b)
                           throws IOException

Reads a long natural number in a limited range using a minimal binary coding. This method is faster than readLongMinimalBinary(long) because it does not have to compute log2b.

Parameters:: b - a strict upper bound.; log2b - the floor of the base-2 logarithm of the bound.
Returns:: the next minimally binary encoded long natural number.
Throws:: IllegalArgumentException - if you try to read a negative number or use a nonpositive base.; IOException
See Also:: OutputBitStream.writeMinimalBinary(int, int)