VariableDatum (DIS-Java-VRML Javadoc)

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mil.navy.nps.dis
Class VariableDatum

java.lang.Object
  mil.navy.nps.dis.PduElement
      mil.navy.nps.dis.VariableDatum

All Implemented Interfaces:: java.lang.Cloneable, SerializationInterface

public class VariableDatum
extends PduElement

Variable-length data.

Version:

1.0

Author:

Don McGregor (http://www.npsnet.org/~mcgredo)

Location:

Web: http://www.web3d.org/WorkingGroups/vrtp/mil/navy/nps/dis/VariableDatum.java

or locally: ~/mil/navy/nps/dis/VariableDatum.java

Hierarchy Diagram:

Summary:

These fields shall specify the types of variable datum, their length, and their value.

Explanation

VariableDatum contains (surprise! a variable amount of data). It consists of a 32-bit enumeration that describes the datum, a 32-bit field that descibes the lenght of the data (in bits) and a data region long enough to contain the data. The data region is allocated in chunks of 64 bits; for example, if the length field specifies a data length of 48 bits, a full 64 bits will be allocated to hold the data, and the remaining 16 bits would be unused padding. Per the specification, padding must be set to zero.

The VariableDatum is used in a variety of places, most notably the DataPdu.

This inherits from PduElement, which means that it must know how to serialize, deSerialize, clone, print its values, and determine its length when serialized.

History:

21Nov96 /Don McGregor /New

10Mar97 /Don McGregor /changes for javadoc

16Apr97 /Don McGregor /PrintStream passed to printValues

06May97 /Don McGregor /Bug fixes: block count not beeing computed correctly; moved computation to central place, made all computations of block size point there. Accessor method variableDatumValue() was always returning null. Bug reports submitted by Dmitry Azovtsev (azov@logos.cyber.mephi.ru).

8Dec97 /Ronan Fauglas /changes for documentation templates + complements in documentation

11Dec97 /Ronan Fauglas /changes access methods names from "variable()" to "getVariable()"

References:

DIS Data Dictionary: Variable Datum Record

DIS specification : IEEE 1278.1, Section 5.3.32

Field Summary
`static int`	`sizeOf` Constant value--size of an empty object WHEN WRITTEN TO THE WIRE; here :`sizeOf = 8 bytes`.
`(package private) int`	`variableDatumID` The Variable Datum ID shall be represented by a 32-bit enumeration.
`(package private) int`	`variableDatumLength` This field shall specify the length of the variable datum in bits.
`(package private) long[]`	`variableDatumValue` These field(s) shall store the value of the variable datum defined by the Variable Datum ID and Variable Datum length.

Constructor Summary
`VariableDatum()` Default constructor--fills with zeros for all values.

Method Summary
`java.lang.Object`	`clone()` Makes deep copies of all the instance variables, so we don't have two objects pointing to the same data.
`void`	`deSerialize(java.io.DataInputStream inputStream)` Deserialize our data from the input stream.
`int`	`getVariableDatumID()`
`int`	`getVariableDatumLength()`
`long[]`	`getVariableDatumValue()`
`int`	`length()` Returns the length of the object when serialized in a stream.
`void`	`printValues(int indentLevel, java.io.PrintStream printStream)` Prints the generated serialized object for debugging.
`void`	`serialize(java.io.DataOutputStream outputStream)` Serialize our data out to the stream.
`void`	`setVariableDatumID(int pVariableDatumID)`
`void`	`setVariableDatumLength(int pVariableDatumLength)`
`void`	`setVariableDatumValue(long[] pVariableDatumValue)`

Methods inherited from class java.lang.Object

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

Field Detail

variableDatumID

int variableDatumID

The Variable Datum ID shall be represented by a 32-bit enumeration.

Value:: Enumeration; see references below for values. *
References:: DIS Data Dictionary : Datum ID Field; See section 7 in the EBV-DOC

variableDatumLength

int variableDatumLength

This field shall specify the length of the variable datum in bits.

References:: DIS Data Dictionary : Variable Datum Length Field

variableDatumValue

long[] variableDatumValue

These field(s) shall store the value of the variable datum defined by the Variable Datum ID and Variable Datum length.

Explanation:: The Variable Datum Value is stored in an array of long integers so as to respect the convention to have a multiple of 64 length.
References:: DIS Data Dictionary: Variable Datum Value/Padding Field

sizeOf

public static final int sizeOf

Constant value--size of an empty object WHEN WRITTEN TO THE WIRE; here :sizeOf = 8 bytes.

See Also:: Constant Field Values

Constructor Detail

VariableDatum

public VariableDatum()

Default constructor--fills with zeros for all values.

Method Detail