Indirect Addressing
6-17
Addressing Modes
Example 6–19. Indirect Addressing With Postindex Add and Bit-Reversed Modify
The address of the operand to fetch is the contents of an auxiliary register
(AR
n). After the operand is fetched, the index register (IR0) is added to the
auxiliary register. This addition is performed with a reverse-carry propagation
and can be used to yield a bit-reversed (B) address. This value replaces the
contents of the auxiliary register.
Operation:
operand address = AR
n
AR
n = B(ARn + IR0)
Assembler Syntax:
*AR
n++(IR0)B
Modification Field:
11001
(+)
0
0
31
24 23
Address
x
x
AR
n
31
x
x
0
31
24 23
Index
Operand
(B)
IR
m