Special Addressing Modes; Program Counter Indirect With Displacement; Program Counter Indirect With Index (8-Bit Displacement) - Motorola CPU32 Reference Manual

3.4.3 Special Addressing Modes

These special addressing modes do not use the register field to specify a register num-
ber but rather to specify a submode.

3.4.3.1 Program Counter Indirect With Displacement

In this mode, the operand is in memory. The address of the operand is the sum of the
address in the program counter and the sign-extended 16-bit displacement integer in
the extension word. The value in the program counter is the address of the extension
word. The reference is a program space reference and is only allowed for read access-
es.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
PROGRAM COUNTER:
DISPLACEMENT:
MEMORY ADDRESS:
NUMBER OF EXTENSION WORDS:

3.4.3.2 Program Counter Indirect with Index (8-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 (8-Bit Displace-
ment), but the program counter is used as the base register.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
PROGRAM COUNTER:
DISPLACEMENT:
INDEX REGISTER:
SCALE:
MEMORY ADDRESS:
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 val-
ue 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 dis-
placement, the program counter, and the index register when specifying this address-
ing mode.
CPU32 DATA ORGANIZATION AND ADDRESSING CAPABILITIES
REFERENCE MANUAL
EA = (PC) + d
16
(d , PC)
16
111
010
31 15
SIGN EXTENDED
1
EA = (PC) + (Xn) + d
(d , PC, Xn. SIZE*SCALE)
8
111
011
31
SIGN EXTENDED
31
SIGN-EXTENDED VALUE
1
31
ADDRESS OF EXTENSION WORD
0
INTEGER
31
OPERAND
8
31
ADDRESS OF EXTENSION WORD
7 0
INTEGER
0
SCALE VALUE
31
OPERAND
0
+
0
0
+
+
X
0
MOTOROLA
3-7