MOTOROLA M68000 FAMILY Programmer's Reference ... - Freescale

MOTOROLA
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
Addressing Capabilities
2.2.7 Address Register Indirect with Index (8-Bit Displacement) Mode
This addressing mode requires one extension word that contains an 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 operand’s address is the sum of the address
register’s contents; the sign-extended displacement value in the extension word’s low-order
eight bits; and the index register’s sign-extended contents (possibly scaled). The user must
specify the address register, the displacement, and the index register in this mode.
GENERATION:
ASSEMBLER SYNTAX:
EA MODE FIELD:
EA REGISTER FIELD:
NUMBER OF EXTENSION WORDS:
ADDRESS REGISTER
DISPLACEMENT
INDEX REGISTER
SCALE
OPERAND POINTER
31
EA = (An) + (Xn) + d8
(d 8 ,An, Xn.SIZE*SCALE)
110
REG. NO.
1
SIGN EXTENDED
SIGN-EXTENDED VALUE
.
7 0
INTEGER
31 0
31
SCALE VALUE
CONTENTS
31 0
X
CONTENTS
POINTS TO
MEMORY OPERAND
+
+
0
2-9