= (Assign an Expression to an Assembler Variable)

The = directive lets you create a symbolic assembler-time variable. Numeric expressions may be assigned to the variable as many times as necessary.

Syntax

Name = Expression

Remarks

The = directive is similar to the EQU assembler directive except you can redefine Name without causing an error condition. However, the = directive is more restrictive about the allowable ExpressionTypes that can be utilized in the Expression field, and it cannot be used to create Text-EquateNames.

Name is a globally-scoped Identifier. The Expression entry must evaluate to an Operand-ExpressionType. If an evaluation error occurs, or if the Expression references an external identifier, or if the Expression evaluates to one of the following Operand-ExpressionTypes:

• Indexed-ExpressionType
  
• Register-ExpressionType
  
• Floating-Point-ExpressionType
  
• Compound-ExpressionType
  
• Duplicated-ExpressionType
then an error message is issued and the assignment does not take place. Otherwise, the Identifier is converted to a Numeric-EquateName.

See also the EQU assembler directive and the EQU preprocessor directive.

Example

EMP = 6       ;Establish as redefineable numeric equate
EMP EQU 6     ;OK, value is the same, EMP remains redefinable
EMP EQU 7     ;Error, can't change value with EQU
EMP = 7       ;OK, EMP is redefineable with =
EMP = EMP+1   ;Can refer to its previous definition

Note: The Expression-Attributes inherited from the Expression during an assignment are not retained in subsequent assignments. For example:

VECTOR = WORD PTR 4          ; Type-Declaration attribute
       MOV [BX],VECTOR       ; Store the 4 as a word
VECTOR = 6                   ; Type-Declaration attribute discarded
       MOV [BX],VECTOR       ; Error, no size for operands

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