Package org.terrier.compression.bit

Interface BitOut

  • All Superinterfaces:
    java.lang.AutoCloseable, java.io.Closeable
    All Known Implementing Classes:
    BitByteOutputStream, BitOutputStream, MemorySBOS
    public interface BitOut
extends java.io.Closeable
    Interface describing the writing compression methods supported by the BitOutputStream classes. Integers written through these compression methods must be greater than 0.
    Since:
    2.0
    Author:
    Craig Macdonald

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      byte getBitOffset()
      Returns the bit offset in the last byte.
      long getByteOffset()
      Returns the byte offset of the stream.
      int writeBinary​(int len, int x)
      Writes an integer in binary format to the stream.
      int writeDelta​(int x)
      Writes an integer x into the stream using delta encoding.
      int writeGamma​(int x)
      Writes an integer x into the stream using gamma encoding.
      int writeGolomb​(int x, int b)
      Writes and integer x into the stream using golomb coding.
      int writeInt​(int x, int len)
      Writes an integer x into the underlying OutputStream.
      int writeInterpolativeCode​(int[] data, int offset, int len, int lo, int hi)
      Writes a sequence of integers using interpolative coding.
      int writeMinimalBinary​(int x, int b)
      Writes an integer x using minimal binary encoding, given an upper bound.
      int writeSkewedGolomb​(int x, int b)
      Writes and integer x into the stream using skewed-golomb coding.
      int writeUnary​(int x)
      Writes an integer x using unary encoding.

      • Methods inherited from interface java.io.Closeable

        close

    • Method Detail

      • getByteOffset

        long getByteOffset()
        Returns the byte offset of the stream. It corresponds to the position of the byte in which the next bit will be written.
        Returns:
        the byte offset in the stream.

      • getBitOffset

        byte getBitOffset()
        Returns the bit offset in the last byte. It corresponds to the position in which the next bit will be written.
        Returns:
        the bit offset in the stream.

      • writeUnary

        int writeUnary​(int x)
        throws java.io.IOException
        Writes an integer x using unary encoding. The encoding is a sequence of x -1 zeros and 1 one: 1, 01, 001, 0001, etc .. This method is not failsafe, it doesn't check if the argument is 0 or negative.
        Parameters:
        x - the number to write
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeGamma

        int writeGamma​(int x)
        throws java.io.IOException
        Writes an integer x into the stream using gamma encoding. This method is not failsafe, it doesn't check if the argument is 0 or negative.
        Parameters:
        x - the int number to write
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeBinary

        int writeBinary​(int len,
                int x)
         throws java.io.IOException
        Writes an integer in binary format to the stream.
        Parameters:
        len - size in bits of the number.
        x - the integer to write.
        Returns:
        the number of bits written.
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeInterpolativeCode

        int writeInterpolativeCode​(int[] data,
                           int offset,
                           int len,
                           int lo,
                           int hi)
                    throws java.io.IOException
        Writes a sequence of integers using interpolative coding. The data must be sorted (increasing order).
        Parameters:
        data - the vector containing the integer sequence.
        offset - the offset into data where the sequence starts.
        len - the number of integers to code.
        lo - a lower bound (must be smaller than or equal to the first integer in the sequence).
        hi - an upper bound (must be greater than or equal to the last integer in the sequence).
        Returns:
        the number of written bits.
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeSkewedGolomb

        int writeSkewedGolomb​(int x,
                      int b)
               throws java.io.IOException
        Writes and integer x into the stream using skewed-golomb coding. Consider a bucket-vector v = <b, 2b, 4b, ... , 2^i b, ...> an integer x is coded as unary(k+1) where k is the index sum(i=0)(k) v_i > x <= sum(i=0)(k+1)
        , so k = log(x/b + 1) sum_i = b(2^n -1) (geometric progression) and the remainder with log(v_k) bits in binary if lower = ceil(x/b) -> lower = 2^i * b -> i = log(ceil(x/b)) + 1 the remainder x - sum_i 2^i*b - 1 = x - b(2^n - 1) - 1 is coded with floor(log(v_k)) bits This method is not failsafe, it doesn't check if the argument or the modulus is 0 or negative.
        Parameters:
        x - the number to write
        b - the parameter for golomb coding
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if and I/O error occurs

      • writeGolomb

        int writeGolomb​(int x,
                int b)
         throws java.io.IOException
        Writes and integer x into the stream using golomb coding. This method is not failsafe, it doesn't check if the argument or the modulus is 0 or negative.
        Parameters:
        x - the number to write
        b - the parameter for golomb coding
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if and I/O error occurs

      • writeMinimalBinary

        int writeMinimalBinary​(int x,
                       int b)
                throws java.io.IOException
        Writes an integer x using minimal binary encoding, given an upper bound. This method is not failsafe, it doesn't check if the argument is 0 or negative.
        Parameters:
        x - the number to write
        b - and strict bound for x
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeDelta

        int writeDelta​(int x)
        throws java.io.IOException
        Writes an integer x into the stream using delta encoding. This method is not failsafe, it doesn't check if the argument is 0 or negative.
        Parameters:
        x - the int number to write
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if an I/O error occurs.

      • writeInt

        int writeInt​(int x,
             int len)
      throws java.io.IOException
        Writes an integer x into the underlying OutputStream. First, it checks if it fits into the current byte we are using for writing, and then it writes as many bytes as necessary
        Parameters:
        x - the int to write
        len - length of the int in bits
        Returns:
        the number of bits written
        Throws:
        java.io.IOException - if an I/O error occurs.