Memory Addressing Modes; Address Register Indirect; Address Register Indirect With Postincrement; Address Register Indirect With Predecrement - Motorola CPU32 Reference Manual

3.4.2 Memory Addressing Modes

These EA modes specify the address of the memory operand.

3.4.2.1 Address Register Indirect

In the address register indirect mode, the operand is in memory, and the address of
the operand is in the address register specified by the register field.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
ADDRESS REGISTER:
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS:

3.4.2.2 Address Register Indirect With Postincrement

In the address register indirect with postincrement mode, the operand is in memory,
and the address of the operand is in the address register specified by the register field.
After the operand address is used, it is incremented by one, two, or four, depending
on the size of the operand: byte, word, or long word. If the address register is the stack
pointer and the operand size is byte, the address is incremented by two rather than
one to keep the stack pointer aligned to a word boundary.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
ADDRESS REGISTER:
OPERAND LENGTH ( 1, 2, OR 4):
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS:

3.4.2.3 Address Register Indirect With Predecrement

In the address register indirect with predecrement mode, the operand is in memory,
and the address of the operand is in the address register specified by the register field.
Before the operand address is used, it is decremented by one, two, or four, depending
on the operand size: byte, word, or long word. If the address register is the stack point-
er and the operand size is byte, the address is decremented by two rather than one to
keep the stack pointer aligned to a word boundary.
MOTOROLA DATA ORGANIZATION AND ADDRESSING CAPABILITIES
3-4
EA = (An)
(An)
010
31
n
An
31
0
EA = (An)
An = An + SIZE
(An) +
011
31
n
An
31
0
MEMORY ADDRESS
OPERAND
MEMORY ADDRESS
+
OPERAND
REFERENCE MANUAL
0
0
0
0
CPU32