Chapter 9 Writing Machine Language Instructions and Directive Statements
Writing Directive Statements 167
9.4.11 dsSyntax
label operation operand
[name] ds expression1 [, expression2 [, expression3]]
expression1 Number of bytes of memory to reserve
expression2 Initial value
expression3 Number of iterations
Default settings
expression2 (initial value) If omitted, the assembler will assume 0.
expression3 (iterations) If omitted, the assembler will assume 1.
Functional description
This directive reserves a memory area of the number of bytes specified by expression1 of the operand.
When expression2 (initial value) is specified, that memory area will be filled with the initial value.
Note that expression2 can be specified only when the value of expression1 is 4 or less. When
expression3 (iterations) is specified, the same specification will be repeated for the number of
iterations. For example, if the operand is 4, 0, 3, a 4-byte area will be filled with 0 three times. Thus, a
12-byte area will be reserved.
When a name is coded for the label, the assembler will assign the current location counter value to that
name.
Operand coding rules
The expression1 (bytes), expression2 (initial value), and expression3 (iterations) coded in the operand
must result in the attribute abs (absolute). Refer to section 8.7.4, "Expression Attributes", regarding
attributes of expressions.
NOTE: When expression2 is omitted, expression3 cannot be specified.