Address Register Indirect With Index (Base Displacement); Special Addressing Modes; Program Counter Indirect With Displacement - Motorola CPU32 Reference Manual

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3.4.2.6 Address Register Indirect With Index (Base Displacement)
The full format indexed 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 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 scaled contents of the sign-extended index register, and
the base displacement.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
PROGRAM COUNTER:
EA
=
(An) + (Xn'SCALE) + db
(bd, An, Xn. SIZE'SCALE)
110
n
31
An
----~
MEMORY ADDRESS
~------------------~--~
31
BASE DISPLACEMENT:
SIGN-EXTENDED VALUE
31
o
INDEX REGISTER:
SIGN-EXTENDED VALUE
SCALE:
SCALE VALUE
MEMORY ADDRESS:
31
NUMBER OF EXTENSION WORDS:
1,2,OR3
OPERAND
3.4.3 Special Addressing Modes
These special addressing modes do not use the register field to specify a
register number 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 accesses.
GENERATION:
ASSEMBLER SYNTAX:
MODE:
REGISTER:
PROGRAM COUNTER:
DISPLACEMENT:
MEMORY ADDRESS:
EA = (PC) + d16
(d16, PC)
111
010
31
ADDRESS OF EXTENSION WORD
31 ----,'-'15'---_ _ _ _ - ; ,
~ ~I~ EXTE~E~
- - l -_ _
IN_T_EG_E_R_---,
31
OPERAND
NUMBER OF EXTENSION WORDS:
MOTOROLA
3-8
DATA ORGANIZATION AND CPU32 REFERENCE MANUAL
ADDRESSING CAPABILITIES