Package org.eclipse.rdf4j.rio.hdt

Class VByte

java.lang.Object
org.eclipse.rdf4j.rio.hdt.VByte
public class VByte extends Object
Variable byte encoding for numbers. A variable number of bytes is used to encode (unsigned) numeric values, the first bit (MSB) of each byte indicates if there are more bytes to read, the other 7 bits are used to encode the value. In this implementation, the MSB is set to 1 if this byte is the last one. E.g: 10000001 is value 1, 00000001 10000001 is 128 (decimal). Note that the value is stored little-endian, so in this example 10000001 00000001.
Author:
Bart.Hanssens
See Also:
Variable byte codes

  • Constructor Summary

    Constructors
    Constructor
    Description
    VByte()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static long
    decode​(byte[] bytes, int len)
    Decode a series of encoded bytes, with a maximum of 8 bytes
    static long
    decode​(InputStream is)
    Decode a maximum of 8 bytes from the input stream.
    static long
    decodeFrom​(byte[] b, int start)
    Decode a maximum of 8 bytes from a byte array.
    static int
    encodedLength​(long value)
    Calculate the number of bytes needed for encoding a value
    static boolean
    hasNext​(byte b)
    Checks if the most significant bit is set.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • VByte

      public VByte()

  • Method Details

    • hasNext

      public static boolean hasNext​(byte b)
      Checks if the most significant bit is set. If this bit is zero, then the next byte must also be read to decode the number.
      Parameters:
      b -
      Returns:
      true if there is a next byte

    • decode

      public static long decode​(byte[] bytes, int len)
      Decode a series of encoded bytes, with a maximum of 8 bytes
      Parameters:
      bytes - byte array
      len - number of bytes to decode
      Returns:
      long value

    • decode

      public static long decode​(InputStream is) throws IOException
      Decode a maximum of 8 bytes from the input stream.
      Parameters:
      is - input stream
      Returns:
      decode value
      Throws:
      IOException

    • decodeFrom

      public static long decodeFrom​(byte[] b, int start) throws IOException
      Decode a maximum of 8 bytes from a byte array.
      Parameters:
      b - byte array
      start - starting position
      Returns:
      decode value
      Throws:
      IOException

    • encodedLength

      public static int encodedLength​(long value)
      Calculate the number of bytes needed for encoding a value
      Parameters:
      value - numeric value
      Returns:
      number of bytes