ADDRESSING

EXAMPLE: MOVE B0,Y: (R1)+

 

 

 

 

BEFORE EXECUTION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B2

B1

 

 

 

 

B0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

55

48 47

24

23

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A F

 

F E D C B A

 

 

7

0 23

0

23

 

 

 

 

 

0

 

 

 

 

 

 

23

Y MEMORY

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$2501

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X

X

X

X

X

X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$2500

X

X

X

X

X

X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

150

R1

$2500

150

N1

XXXX

150

M1

$FFFF

Assembler Syntax: (Rn)+

Memory Spaces: P:, X:, Y:, XY:, L:

Additional Instruction Execution Time (Clocks): 0

Additional Effective Address Words: 0

 

 

 

AFTER EXECUTION

 

 

B2

B1

B0

 

55

48 47

 

24

23

0

 

 

 

A F

6 5 4 3 2 1

F E D C B A

7

0 23

 

0

23

0

Y MEMORY

 

23

 

 

 

 

 

0

$2501

X X

X X

X

X

X

$2500

$

F E

D

C

B

A

 

 

 

15

 

 

 

0

 

 

R1

 

 

$2501

 

 

 

 

15

 

 

 

0

 

 

N1

 

 

XXXX

 

 

 

 

15

 

 

 

0

 

M1

 

 

$FFFF

 

Figure 4-5 Address Register Indirect — Postincrement

Rn without an associated data move.

4.4.1.5Postdecrement By Offset Nn

The address of the operand is in the address register, Rn (see Table 4-1and Figure 4-8). After the operand address is used, it is decremented by the contents of the Nn register and stored in the same address register. The contents of the Nn register are unchanged. This mode cannot be used for making XY: memory references, but it can be used to mod-

MOTOROLA

ADDRESS GENERATION UNIT

4 - 11

Page 64
Image 64
Motorola DSP56000, 24-Bit Digital Signal Processor Address Register Indirect Postincrement, Postdecrement By Offset Nn