ptolemy.data

Class UnsignedByteToken

java.lang.Object

ptolemy.data.Token

ptolemy.data.ScalarToken

ptolemy.data.UnsignedByteToken

All Implemented Interfaces:

BitwiseOperationToken, PartiallyOrderedToken

public class UnsignedByteToken
extends ScalarToken

A token that contains a byte number in the range 0 through 255. This UnsignedByteToken definition is in contrast to Java's definition of a byte as a number in the range -128 through 127.

Overflow and underflow are handled by returning the result of all operations modulo 256. Thus, the result is always in the range 0 through 255. Likewise, constructors of this class generate tokens whose values are the argument modulo 256. Note, for example, that UnsignedByteToken((byte)(-100)) generates a UnsignedByteToken representing the value 156, which is -100 modulo 256.

Note, also, that the byteValue() method returns a Java byte in the range -128 through 127. This is in contrast to the intValue(), longValue(), doubleValue(), and complexValue() methods which all return values in the range 0 through 255. The value returned by byteValue() is the value represented by the UnsignedByteToken but with 256 subtracted if this value is greater than 127. In other words, the result and the argument are equal modulo 256.

Since:

Ptolemy II 2.0

Version:

$Id$

Author:

Winthrop Williams, Steve Neuendorffer, Contributor: Christopher Hylands

Pt.AcceptedRating:

Red (winthrop)

Pt.ProposedRating:

Yellow (cxh) ONE, ZERO, nil Token

Field Summary

Fields

Modifier and Type	Field and Description
static UnsignedByteToken	NIL A token that represents a missing value.
static UnsignedByteToken	ONE A UnsignedByteToken with the value 1.
static UnsignedByteToken	ZERO A UnsignedByteToken with the value 0.

Fields inherited from class ptolemy.data.ScalarToken

_unitCategoryExponents

Constructor Summary

Constructors

Constructor and Description
UnsignedByteToken() Construct a token with byte 0.
UnsignedByteToken(byte value) Construct a UnsignedByteToken with the specified byte value.
UnsignedByteToken(int value) Construct a UnsignedByteToken with the specified integer value.
UnsignedByteToken(java.lang.String init) Construct a UnsignedByteToken from the specified string.

Method Summary

Modifier and Type	Method and Description
protected ScalarToken	_absolute() Return a ScalarToken containing the absolute value of the value of this token.
protected ScalarToken	_add(ScalarToken rightArgument) Return a new token whose value is the value of the argument Token added to the value of this Token.
protected ScalarToken	_bitwiseAnd(ScalarToken rightArgument) Returns a token representing the bitwise AND of this token and the given token.
protected ScalarToken	_bitwiseNot() Returns a token representing the bitwise NOT of this token.
protected ScalarToken	_bitwiseOr(ScalarToken rightArgument) Returns a token representing the bitwise OR of this token and the given token.
protected ScalarToken	_bitwiseXor(ScalarToken rightArgument) Returns a token representing the bitwise XOR of this token and the given token.
protected ScalarToken	_divide(ScalarToken rightArgument) Return a new token whose value is the value of this token divided by the value of the argument token.
protected BooleanToken	_isCloseTo(ScalarToken rightArgument, double epsilon) Test whether the value of this token is close to the first argument, where "close" means that the distance between them is less than or equal to the second argument.
protected BooleanToken	_isLessThan(ScalarToken rightArgument) Test for ordering of the values of this Token and the argument Token.
protected ScalarToken	_modulo(ScalarToken rightArgument) Return a new token whose value is the value of this token modulo the value of the argument token.
protected ScalarToken	_multiply(ScalarToken rightArgument) Return a new token whose value is the value of this token multiplied by the value of the argument token.
protected ScalarToken	_subtract(ScalarToken rightArgument) Return a new token whose value is the value of the argument token subtracted from the value of this token.
byte	byteValue() Return the value in this token as a byte, modulo 256.
Complex	complexValue() Return the value of this token as a Complex.
static UnsignedByteToken	convert(Token token) Convert the specified token into an instance of UnsignedByteToken.
double	doubleValue() Return the value in the token as a double.
boolean	equals(java.lang.Object object) Return true if the class of the argument is UnsignedByteToken, and it has the same value as this token.
Type	getType() Return the type of this token.
int	hashCode() Return a hash code value for this token.
int	intValue() Return the value in the token as an integer.
boolean	isNil() Return true if the token is nil, (aka null or missing).
ScalarToken	leftShift(int bits) Returns a token representing the result of shifting the bits of this token towards the most significant bit, filling the least significant bits with zeros.
ScalarToken	logicalRightShift(int bits) Returns a token representing the result of shifting the bits of this token towards the least significant bit, filling the most significant bits with zeros.
long	longValue() Return the value in the token as a long.
Token	one() Returns an UnsignedByteToken with value 1.
ScalarToken	rightShift(int bits) Returns a token representing the result of shifting the bits of this token towards the least significant bit, filling the most significant bits with the sign of the value.
short	shortValue() Return the value in the token as a short.
java.lang.String	toString() Return the value of this token as a string that can be parsed by the expression language to recover a token with the same value.
static short	unsignedConvert(byte value) Convert a byte to an integer, treating the byte as an unsigned value in the range 0 through 255.
Token	zero() Returns an UnsignedByteToken with value 0.

Methods inherited from class ptolemy.data.ScalarToken

_addCategoryExponents, _areUnitsEqual, _copyOfCategoryExponents, _isEqualTo, _isUnitless, _subtractCategoryExponents, absolute, add, addReverse, bitwiseAnd, bitwiseNot, bitwiseOr, bitwiseXor, divide, divideReverse, fixValue, floatValue, inUnitsOf, isCloseTo, isEqualTo, isGreaterThan, isLessThan, isLessThan, modulo, moduloReverse, multiply, multiplyReverse, setUnitCategory, subtract, subtractReverse, unitsString

Methods inherited from class ptolemy.data.Token

isCloseTo, notSupportedConversionMessage, notSupportedIncomparableConversionMessage, notSupportedIncomparableMessage, notSupportedMessage, notSupportedNullNilStringMessage, pow, zeroReturnType

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NIL

public static final UnsignedByteToken NIL

A token that represents a missing value. Null or missing tokens are common in analytical systems like R and SAS where they are used to handle sparsely populated data sources. In database parlance, missing tokens are sometimes called null tokens. Since null is a Java keyword, we use the term "nil". The toString() method on a nil token returns the string "nil".

ONE

public static final UnsignedByteToken ONE

A UnsignedByteToken with the value 1.

ZERO

public static final UnsignedByteToken ZERO

A UnsignedByteToken with the value 0.

Constructor Detail

UnsignedByteToken

public UnsignedByteToken()

Construct a token with byte 0.

UnsignedByteToken

public UnsignedByteToken(byte value)

Construct a UnsignedByteToken with the specified byte value. The UnsignedByteToken constructed represents a value in the range 0 through 255. However, the byte passed in as the argument to this method represents a value in Java in the range -128 to 127. Due to the difference between these definitions, this method effectively adds 256 if the argument is negative, resulting in a positive value for the UnsignedByteToken.

Parameters:

value - The specified value.

UnsignedByteToken

public UnsignedByteToken(int value)

Construct a UnsignedByteToken with the specified integer value. The UnsignedByteToken constructed represents a value in the range 0 through 255. However, the integer passed in as the argument to this method represents a value in Java in the range -2^31 to (2^31)-1. This method's cast to (byte) keeps only the low order 8 bits of the integer. This effectively adds or subtracts a multiple of 256 to/from the argument. The resulting UnsignedByteToken falls in the range 0 through 255.

Parameters:

value - The specified value.

UnsignedByteToken

public UnsignedByteToken(java.lang.String init)
                  throws IllegalActionException

Construct a UnsignedByteToken from the specified string. The string is parsed by the parseByte() method of the Java Byte object.

Parameters:

init - The initialization string, which is an integer from 0 to 255. -1 and 256 are illegal values.

Throws:

IllegalActionException - If the token could not be created from the given string.

Method Detail

byteValue

public byte byteValue()

Return the value in this token as a byte, modulo 256. The UnsignedByteToken being converted represents a value in the range 0 through 255. However, the Java byte it is being converted to represents a value in the range -128 through 127. Thus, this method has the effect subtracting 256 from the value if the value is greater than 127.

Overrides:

byteValue in class ScalarToken

Returns:

The byte value contained in this token, modulo 256.

complexValue

public Complex complexValue()

Return the value of this token as a Complex. The real part of the Complex is the value of this token, the imaginary part is set to 0.

Overrides:

complexValue in class ScalarToken

Returns:

A Complex.

convert

public static UnsignedByteToken convert(Token token)
                                 throws IllegalActionException

Convert the specified token into an instance of UnsignedByteToken. The units of the returned token will be the same as the units of the given token. If the argument is already an instance of UnsignedByteToken, it is returned without any change. If the argument is null or a nil token, then NIL is returned. Otherwise, if the argument is above UnsignedByteToken in the type hierarchy or is incomparable with UnsignedByteToken, an exception is thrown with a message stating that either the conversion is not supported, or the types are incomparable. If none of the above conditions is met, then the argument must be below UnsignedByteToken in the type hierarchy. However, not such types exist at this time, so an exception is thrown with a message stating simply that the conversion is not supported.

Parameters:

token - The token to be converted to a UnsignedByteToken.

Returns:

A UnsignedByteToken.

Throws:

IllegalActionException - If the conversion cannot be carried out.

doubleValue

public double doubleValue()

Return the value in the token as a double.

Overrides:

doubleValue in class ScalarToken

Returns:

The value contained in this token as a double.

equals

public boolean equals(java.lang.Object object)

Return true if the class of the argument is UnsignedByteToken, and it has the same value as this token.

Overrides:

equals in class java.lang.Object

Parameters:

object - An instance of Object.

Returns:

True if the argument is an instance of UnsignedByteToken with the same value. If either this object or the argument is a nil Token, return false.

getType

public Type getType()

Return the type of this token.

Specified by:

getType in class ScalarToken

Returns:

BaseType.UNSIGNED_BYTE

hashCode

public int hashCode()

Return a hash code value for this token. This method just returns the value of this token.

Overrides:

hashCode in class java.lang.Object

Returns:

A hash code value for this token.

intValue

public int intValue()

Return the value in the token as an integer.

Overrides:

intValue in class ScalarToken

Returns:

The byte value contained in this token as a int.

isNil

public boolean isNil()

Return true if the token is nil, (aka null or missing). Nil or missing tokens occur when a data source is sparsely populated.

Overrides:

isNil in class Token

Returns:

True if the token is the NIL token.

leftShift

public ScalarToken leftShift(int bits)

Returns a token representing the result of shifting the bits of this token towards the most significant bit, filling the least significant bits with zeros.

Overrides:

leftShift in class ScalarToken

Parameters:

bits - The number of bits to shift.

Returns:

The left shift. If this token is nil, then NIL is returned.

logicalRightShift

public ScalarToken logicalRightShift(int bits)

Returns a token representing the result of shifting the bits of this token towards the least significant bit, filling the most significant bits with zeros. This treats the value as an unsigned number, which may have the effect of destroying the sign of the value.

Overrides:

logicalRightShift in class ScalarToken

Parameters:

bits - The number of bits to shift.

Returns:

The logical right shift. If this token is nil, then NIL is returned.

longValue

public long longValue()

Return the value in the token as a long.

Overrides:

longValue in class ScalarToken

Returns:

The byte value contained in this token as a long.

one

public Token one()

Returns an UnsignedByteToken with value 1.

Overrides:

one in class Token

Returns:

an UnsignedByteToken with value 1.

rightShift

public ScalarToken rightShift(int bits)

Returns a token representing the result of shifting the bits of this token towards the least significant bit, filling the most significant bits with the sign of the value. This preserves the sign of the result.

Overrides:

rightShift in class ScalarToken

Parameters:

bits - The number of bits to shift.

Returns:

The right shift. If this token is nil, then NIL is returned.

shortValue

public short shortValue()

Return the value in the token as a short.

Overrides:

shortValue in class ScalarToken

Returns:

The value contained in this token as a short.

toString

public java.lang.String toString()

Return the value of this token as a string that can be parsed by the expression language to recover a token with the same value. If this token has a unit, the return string also includes a unit string produced by the unitsString() method in the super class.

Overrides:

toString in class Token

Returns:

A String representing the byte value and the units (if any) of this token.

See Also:

ScalarToken.unitsString()

unsignedConvert

public static short unsignedConvert(byte value)

Convert a byte to an integer, treating the byte as an unsigned value in the range 0 through 255. Note that Java defines the byte as having a value ranging from -128 through 127, so 256 is added if this value is negative.

Parameters:

value - The byte to convert to an unsigned byte.

Returns:

An integer in the range 0 through 255.

zero

public Token zero()

Returns an UnsignedByteToken with value 0.

Overrides:

zero in class Token

Returns:

An UnsignedByteToken with value 0.

_absolute

protected ScalarToken _absolute()

Return a ScalarToken containing the absolute value of the value of this token. If this token contains a non-negative number, it is returned directly; otherwise, a new token is is return. Note that it is explicitly allowable to return this token, since the units are the same. Since we have defined the byte as ranging from 0 through 255, its absolute value is equal to itself. Although this method does not actually do anything, it is included to make the UnsignedByteToken interface compatible with the interfaces of the other types.

Specified by:

_absolute in class ScalarToken

Returns:

An UnsignedByteToken.

_add

protected ScalarToken _add(ScalarToken rightArgument)

Return a new token whose value is the value of the argument Token added to the value of this Token. It is assumed that the type of the argument is an UnsignedByteToken. Overflow is handled by subtracting 256 so that the resulting sum falls in the range 0 through 255.

Specified by:

_add in class ScalarToken

Parameters:

rightArgument - The token to add to this token.

Returns:

A new UnsignedByteToken containing the result.

_bitwiseAnd

protected ScalarToken _bitwiseAnd(ScalarToken rightArgument)

Returns a token representing the bitwise AND of this token and the given token. It is assumed that the type of the argument is UnsignedByteToken.

Specified by:

_bitwiseAnd in class ScalarToken

Parameters:

rightArgument - The UnsignedByteToken to bitwise AND with this one.

Returns:

The bitwise AND.

_bitwiseNot

protected ScalarToken _bitwiseNot()

Returns a token representing the bitwise NOT of this token.

Specified by:

_bitwiseNot in class ScalarToken

Returns:

The bitwise NOT of this token.

_bitwiseOr

protected ScalarToken _bitwiseOr(ScalarToken rightArgument)

Returns a token representing the bitwise OR of this token and the given token. It is assumed that the type of the argument is UnsignedByteToken.

Specified by:

_bitwiseOr in class ScalarToken

Parameters:

rightArgument - The UnsignedByteToken to bitwise OR with this one.

Returns:

The bitwise OR.

_bitwiseXor

protected ScalarToken _bitwiseXor(ScalarToken rightArgument)

Returns a token representing the bitwise XOR of this token and the given token. It is assumed that the type of the argument is UnsignedByteToken.

Specified by:

_bitwiseXor in class ScalarToken

Parameters:

rightArgument - The UnsignedByteToken to bitwise XOR with this one.

Returns:

The bitwise XOR.

_divide

protected ScalarToken _divide(ScalarToken rightArgument)

Return a new token whose value is the value of this token divided by the value of the argument token. It is assumed that the type of the argument is an UnsignedByteToken. The result will be a byte containing the quotient. For example, 255 divided by 10 returns 25. This method does not test for or attempt to prevent division by 0.

Specified by:

_divide in class ScalarToken

Parameters:

rightArgument - The token to divide this token by.

Returns:

A new UnsignedByteToken containing the result.

_isCloseTo

protected BooleanToken _isCloseTo(ScalarToken rightArgument,
                                  double epsilon)

Test whether the value of this token is close to the first argument, where "close" means that the distance between them is less than or equal to the second argument. It is assumed that the argument is an UnsignedByteToken.

Specified by:

_isCloseTo in class ScalarToken

Parameters:

rightArgument - The token to compare to this token.

epsilon - The distance.

Returns:

A true-valued token if the first argument is close to this token.

_isLessThan

protected BooleanToken _isLessThan(ScalarToken rightArgument)

Test for ordering of the values of this Token and the argument Token. It is assumed that the type of the argument is UnsignedByteToken.

Specified by:

_isLessThan in class ScalarToken

Parameters:

rightArgument - The token to add to this token.

Returns:

A new Token containing the result.

_modulo

protected ScalarToken _modulo(ScalarToken rightArgument)

Return a new token whose value is the value of this token modulo the value of the argument token. It is assumed that the type of the argument is UnsignedByteToken. This method does not test for or attempt to prevent division by 0.

Specified by:

_modulo in class ScalarToken

Parameters:

rightArgument - The token to modulo this token by.

Returns:

A new UnsignedByteToken containing the result.

_multiply

protected ScalarToken _multiply(ScalarToken rightArgument)

Return a new token whose value is the value of this token multiplied by the value of the argument token. It is assumed that the type of the argument is UnsignedByteToken. Overflow is handled by subtracting the multiple of 256 which puts the result into the range 0 through 255. In other words, return the product modulo 256.

Specified by:

_multiply in class ScalarToken

Parameters:

rightArgument - The token to multiply this token by.

Returns:

A new UnsignedByteToken containing the product modulo 256.

_subtract

protected ScalarToken _subtract(ScalarToken rightArgument)

Return a new token whose value is the value of the argument token subtracted from the value of this token. It is assumed that the type of the argument is UnsignedByteToken. Underflow is handled by adding 256 to the result if it is less than 0. Thus the result is always in the range 0 through 255.

Specified by:

_subtract in class ScalarToken

Parameters:

rightArgument - The token to subtract from this token.

Returns:

A new UnsignedByteToken containing the difference modulo 256.