Texas Instruments TMS320C3x User Manual
Page 168
Indirect Addressing
6-15
Addressing Modes
Example 6–15. Indirect Addressing With Postindex Add and 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 or IR1) is added
to the auxiliary register.
Operation:
operand address = AR
n
AR
n = ARn + IRm
Assembler Syntax:
*AR
n ++ (IRm)
Modification Field:
01100
if
m = 0
10100
if
m = 1
Index
(+)
0
0
31
24 23
Address
x
x
AR
n
31
x
x
0
31
24 23
Operand
IR
m
Example 6–16. Indirect Addressing With Postindex Subtract and 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 or IR1) is subtracted from
the auxiliary register.
Operation:
operand address = AR
n
AR
n = ARn – IRm
Assembler Syntax:
*AR
n – – (IRm)
Modification Field:
01101
if
m = 0
10101
if
m = 1
(–)
0
0
31
24
23
Address
x
x
AR
n
31
IR
m
x
x
0
31
24 23
Index
Operand