A combination of numeric values, symbols, and operators can be written as an expression.
- | A space character or a tab can be inserted between an operator and a numeric value. |
- | Multiple operators can be used in combination. |
- | When using an expression as a symbol value, make sure that the value of the expression is determined at assembly. |
- | A character constant must not be used as a term of an expression. |
- | The expression value as a result of operation must be within the range from 2147483648 to 2147483647. The assembler does not check if the result is outside this range. |
The following is a list of the operators that can be written in programs.
Table 5.7 | Unary Operators |
|
|
|
|
+
|
Handles the value that follows the operator as a positive value.
|
|
-
|
Handles the value that follows the operator as a negative value.
|
|
~
|
Logically negates the value that follows the operator.
|
|
SIZEOF
|
Handles the size (bytes) of the section specified in the operand as a value.
|
|
TOPOF
|
Handles the start address of the section specified in the operand as a value.
|
Be sure to insert a space character or a tab between the operand and SIZEOF or TOPOF.
Example: SIZEOF program
Table 5.8 | Binary Operators |
|
|
|
|
+
|
Adds the lvalue and rvalue.
|
|
-
|
Subtracts the rvalue from the lvalue.
|
|
*
|
Multiplies the lvalue and rvalue.
|
|
/
|
Divides the lvalue by the rvalue.
|
|
%
|
Obtains the remainder by dividing the lvalue by the rvalue.
|
|
>>
|
Shifts the lvalue to the right by the number of bits specified by the rvalue.
|
|
<<
|
Shifts the lvalue to the left by the number of bits specified by the rvalue.
|
|
&
|
Logically ANDs the lvalue and rvalue in bitwise.
|
|
|
|
Logically (inclusively) ORs the lvalue and rvalue in bitwise.
|
|
^
|
Exclusively ORs the lvalue and rvalue in bitwise.
|
A conditional operator can be used only in the operand of the .IF or .ELIF directive.
Table 5.9 | Conditional Operators |
|
|
|
|
>
|
Evaluates if the lvalue is greater than the rvalue.
|
|
<
|
Evaluates if the lvalue is smaller than the rvalue.
|
|
>=
|
Evaluates if the lvalue is equal to or greater than the rvalue.
|
|
<=
|
Evaluates if the lvalue is equal to or smaller than the rvalue.
|
|
==
|
Evaluates if the lvalue is equal to the rvalue.
|
|
!=
|
Evaluates if the lvalue is not equal to the rvalue.
|
- | Precedence designation operator |
Table 5.10 | Precedence Designation Operator |
|
|
|
|
()
|
An operation enclosed within ( ) takes precedence. If multiple pairs of parentheses are used in an expression, the left pair is given precedence over the right pair. Parentheses can be nested.
|
(b) | Order of Expression Evaluation |
The expression in an operand is evaluated in accordance with the following precedence and the resultant value is handled as the operand value.
- | The operators are evaluated in the order of their precedence. The operator precedence is shown in the following table. |
- | Operators having the same precedence are evaluated from left to right. |
- | An operation enclosed within parentheses takes the highest precedence. |
Table 5.11 | Order of Expression Evaluation |
|
|
|
|
|
1
|
Precedence designation operator
|
()
|
|
2
|
Unary operator
|
+, -, ~, SIZEOF, TOPOF
|
|
3
|
Binary operator 1
|
*, /, %
|
|
4
|
Binary operator 2
|
+, -
|
|
5
|
Binary operator 3
|
>>, <<
|
|
6
|
Binary operator 4
|
&
|
|
7
|
Binary operator 5
|
|, ^
|
|
8
|
Conditional operator
|
>, <, >=, <=, ==, !=
|