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3.4.3.2 Program Counter Indirect with Index (a-Bit Displacement)
This mode is similar to the address register indirect with index (8-bit
displacement) mode described in 3.4.2.5 Address Register Indirect With
Index (a-Bit Displacement), but the program counter is used as the base
register.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
PROGRAM COUNTER:
DISPLACEMENT:
INDEX REGISTER:
SCALE:
MEMORY ADDRESS:
EA
=
(PC) + (Xn) + dS
(dS, PC, Xn. SIZE'SCALE)
~~~
r-
31 _ _ _ _ _ _ _ _ _ _ _ ---.
31 _ _ _ _ _ _ _ ---.-:. _ _ _ --.:::..,
:= _
~I~ EEE~E~
_
INTEGER
I------~
31
SIGN-EXTENDED VALUE
SCALE VALUE
31
NUMBER OF EXTENSION WORDS:
The operand is in memory. The address of the operand is the sum of the
address in the program counter, the sign-extended displacement integer in the
lower eight bits of the extension word, and the sized, scaled, and Sign-extended
index operand.
The value in the program counter is the address of the
extension word.
This reference is a program space reference and is only
allowed for reads.
The user must include the displacement, the program
counter, and the index register when specifying this addressing mode.
3.4.3.3 Program Counter Indirect with Index (Base Displacement)
This mode is similar to the address register indirect with index (base
displacement) mode described in 3.4.2.6 Address Register Indirect With
Index (Base Displacement), but the program counter is used as the base
register.
It requires an index register indicator and an optional 16- or 32-bit
Sign-extended base displacement.
The operand is in memory. The address of the operand is the sum of the
contents of the program counter, the scaled contents of the sign-extended index
register, and the base displacement. The value of the program counter is the
address of the first extension word. The reference is a program space reference
and is only allowed for read accesses.
CPU32 REFERENCE MANUAL
DATA ORGANIZATION AND
ADDRESSING
CAPABILITIES
MOTOROLA
3-9
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