
CPU32
REFERENCE MANUAL
DATA ORGANIZATION AND ADDRESSING CAPABILITIES
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MOTOROLA
3-5
3.4.2.4 Address Register Indirect With Displacement
In the address register indirect with displacement mode, the operand is in memory.
The address of the operand is the sum of the address in the address register plus the
sign-extended 16-bit displacement integer in the extension word. Displacements are
always sign extended to 32 bits before being used in EA calculations.
3.4.2.5 Address Register Indirect With Index (8-Bit Displacement)
This mode requires one extension word that contains the index register indicator and
an 8-bit displacement. The index register indicator includes size and scale information.
In this mode, the operand is in memory. The address of the operand is the sum of the
contents of the address register, the sign-extended displacement value in the low-or-
der eight bits of the extension word, and the sign-extended contents of the index reg-
ister (possibly scaled). The user must specify displacement, address register, and
index register.
This address mode can have either of two different formats of extension. The brief for-
mat (8-bit displacement) requires one word of extension and provides fast indexed ad-
dressing. The full format (16 and 32-bit displacement) provides optional displacement
size. Both forms use an index operand.
For brief format addressing, the address of the operand is the sum of the address in
the address register, the sign-extended displacement integer in the low-order eight
bits of the extension word, and the index operand. The reference is classed as a data
reference, except for the JMP and JSR instructions. The index operand is specified
“Ri.sz*scl”.
OPERAND
MEMORY ADDRESS
0
31
0
31
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS: 0
OPERAND LENGTH (1, 2, OR 4):
An = An SIZE
EA = (An)
(An)
100
n
An
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
ADDRESS REGISTER:
+
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
ADDRESS REGISTER:
DISPLACEMENT:
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS: 1
EA = (An) + d
(d16,
101
n
An
MEMORY ADDRESS
OPERAND
0
0
31
31
15
0
31
SIGN EXTENDED
INTEGER
16
F
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n
.