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 |
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+
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Handles the value that follows the operator as a positive value.
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-
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Handles the value that follows the operator as a negative value.
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~
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Logically negates the value that follows the operator.
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SIZEOF
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Handles the size (bytes) of the section specified in the operand as a value.
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TOPOF
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Handles the start address of the section specified in the operand as a value.
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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 |
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+
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Adds the lvalue and rvalue.
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-
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Subtracts the rvalue from the lvalue.
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*
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Multiplies the lvalue and rvalue.
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/
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Divides the lvalue by the rvalue.
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%
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Obtains the remainder by dividing the lvalue by the rvalue.
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>>
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Shifts the lvalue to the right by the number of bits specified by the rvalue.
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<<
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Shifts the lvalue to the left by the number of bits specified by the rvalue.
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&
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Logically ANDs the lvalue and rvalue in bitwise.
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Logically (inclusively) ORs the lvalue and rvalue in bitwise.
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^
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Exclusively ORs the lvalue and rvalue in bitwise.
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A conditional operator can be used only in the operand of the .IF or .ELIF directive.
Table 5.9 | Conditional Operators |
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>
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Evaluates if the lvalue is greater than the rvalue.
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<
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Evaluates if the lvalue is smaller than the rvalue.
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>=
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Evaluates if the lvalue is equal to or greater than the rvalue.
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<=
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Evaluates if the lvalue is equal to or smaller than the rvalue.
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==
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Evaluates if the lvalue is equal to the rvalue.
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!=
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Evaluates if the lvalue is not equal to the rvalue.
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- | Precedence designation operator |
Table 5.10 | Precedence Designation Operator |
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()
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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.
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(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 |
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1
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Precedence designation operator
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()
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2
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Unary operator
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+, -, ~, SIZEOF, TOPOF
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3
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Binary operator 1
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*, /, %
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4
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Binary operator 2
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+, -
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5
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Binary operator 3
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>>, <<
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6
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Binary operator 4
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&
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7
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Binary operator 5
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|, ^
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8
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Conditional operator
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>, <, >=, <=, ==, !=
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