Bitwise and Logical Operators

Description
Syntax
Operation

Remarks
Examples
Version History & Bug list

Operators are used to compare two values in various ways.

1: An Operator that performs a bitwise conjunction on the surrounding expressions.
2: An Operator that performs a logical conjunction on the surrounding expressions.

For Bitwise Operators, the ooPIC performs a bitwise comparison of identically positioned bits in two numeric expressions and sets the corresponding bit in the result according to the logic specified by the operator.

For Logical Operators, the ooPIC uses bit 1 exclusively to determine if a value is true or false and therefore, makes no distinction between a logical operator used in an if/then statement and a bitwise operator used to modify a variable. Both bitwise and logical applications will expect the same syntax and operate in a similar manner. In firmware version B3, Local operators &&, II and ! were added to the C syntax which considers any value other than zero to have bit 1 set. See Version history for more detail.

Syntax:

The following shows the format of the Bitwise/Logical Operator syntax.

	Basic Bitwise/Logical	C & Java Bitwise	C & Java Logical
And	<exp1> And <exp2>	<exp1> & <exp2>	<exp1> && <exp2>
Or	<exp1> Or <exp2>	<exp1> \| <exp2>	<exp1> \|\| <exp2>
XOR	<exp1> XOR <exp2>	<exp1> ^ <exp2>
Not	Not <exp1>	~ <exp1>	! <exp1>

The following table lists the elements of the Bitwise/Logical Operator syntax.

Element Description

<exp1> Any valid exp.

<exp2> Any valid exp.

Operation:

Logical And evaluates as follows: If, and only if, both expressions evaluate to cvTrue, the result is cvTrue. If either exp evaluates to cvFalse, the result is cvFalse.

Bitwise And performs a bitwise evaluation of identically positioned bits in two numeric expressions and writes the corresponding bit in the result.

The following table illustrates how the results are determined:

<Exp1>
<Exp2>
Evaluation

False
False
False

True
False
False

False
True
False

True
True
True

Logical Or evaluates as follows: If, either of the expressions evaluate to cvTrue, the result is cvTrue.

Bitwise Or operator also performs a bitwise evaluation of identically positioned bits in two numeric expressions and writes the corresponding bit in the result.

The following table illustrates how result is determined:

<Exp1>
<Exp2>
Evaluation

False
False
False

True
False
True

False
True
True

True
True
True

Logical XOR evaluates as follows: If, either of the expressions evaluate to cvTrue, but not both, the result is cvTrue.

Bitwise XOR operator also performs a bitwise evaluation of identically positioned bits in two numeric expressions and writes the corresponding bit in the result.

The following table illustrates how result is determined:

<Exp1>
<Exp2>
Evaluation

False
False
False

True
False
True

False
True
True

True
True
False

Logical Not inverts the evaluation of the expressions.

Bitwise Not operator also performs a bitwise invert of bits in <exp1> and writes the corresponding bit in the result.

The following table illustrates how result is determined:

<Exp1>
Evaluation

False
True

True
False

Remarks:

Logical Operators can also be done with the oMath Object.

Example:

The following are simple uses for logical and bitwise operators.

Visual Basic Syntax

C and Java Syntax

'Logical operator

If (A>0) And (A<45) Then
 '<statements>
End If

'Bitwise operation

A = B And C

//Logical operator

If ((A>0) && (A<45)) {
 //<statements>
}

//Bitwise operation

A = B & C;

Basic Syntax

'Logical operator

If (A>0) And (A<45) Then '<statements>

'Bitwise operation

A = B And C