MC68030 Datasheet, PDF (51/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Data Organization and Addressing Capabilities
2.4.8 Address Register Indirect with Index (Base Displacement) Mode
This addressing mode requires an index register indicator and an optional 16- or 32-bit sign-
extended base displacement. The index register indicator includes size and scaling
information. The operand is in memory. The address of the operand is the sum of the
contents of the address register, the scaled contents of the sign-extended index register,
and the base displacement.
In this mode, the address register, the index register, and the displacement are all optional.
If none is specified, the effective address is zero. This mode provides a data register indirect
address when no address register is specified and the index register is a data register (Dn).
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
ADDRESS REGISTER:
EA = (An) + (Xn) + bd
(bd,An,Xn.SIZE*SCALE)
110
n
31
An
0
MEMORY ADDRESS
31
0
BASE DISPLACEMENT:
SIGN-EXTENDED VALUE
+
31
0
INDEX REGISTER:
SIGN-EXTENDED VALUE
SCALE:
7
0
SCALE VALUE
X
+
31
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS:
1,2, OR 3
0
OPERAND
MOTOROLA
MC68030 USER’S MANUAL
2-13