Address Modifier Arithmetic Types; Address Register Indirect — Postdecrement By Offset Nn - Motorola DSP56000 Manual

EXAMPLE: MOVE X:(R4)–N4,A0
BEFORE EXECUTION
A2 A1
55 48 47
0 F 7 4 1 0 5
7 0 23
$7706
$7703
Assembler Syntax: (Rn)–Nn
Memory Spaces: P:, X:, Y:, L:
Additional Instruction Execution Time (Clocks): 0
Additional Effective Address Words: 0
Figure 4-8 Address Register Indirect — Postdecrement by Offset Nn
move.
4.4.2

Address Modifier Arithmetic Types

The address ALU supports linear, modulo, and reverse-carry arithmetic for all address
register indirect modes. These arithmetic types easily allow the creation of data structures
in memory for FIFOs (queues), delay lines, circular buffers, stacks, and bit-reversed FFT
buffers.
4 - 14
ADDRESSING
A0
24 23 0
A 3 F A 6 B 0
0 23 0
X MEMORY
23 0
$ 5 0 5 0 5 0
X X X X X X
15 0
R4 $7706
15 0
N4 $0003
15 0
M4 $FFFF
ADDRESS GENERATION UNIT
AFTER EXECUTION
A2 A1
55 48 47 24 23
0 F 7 4 1 0 5 A
7 0 23 0 23
23
$7706
X X X X X X
$7703
A0
0
5 0 5 0 5 0
0
X MEMORY
0
$ 5 0 5 0 5 0
15 0
R4 $7703
15 0
N4 $0003
15 0
M4 $FFFF
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