3.4.3 Effective Address Calculation
Table 3-8 explains how the effective address is calculated in each addressing mode.
Table 3-8 Effective Address Calculation
No. Addressing Mode Effective Address Calculation Effective Address
1 Register direct — Operand is contents of
Rn Rn
1010Sz rrr
2 Register indirect — 23 15 0
@Rn DP
*
1
Rn
1101Sz rrr
Or TP or EP
*
2
3 Register indirect 8 Bits
with displacement 15 0 23 15 0
@(d:8,Rn) Rn DP
*
1
Result
15 0 Or TP or EP
*
2
1110Sz rrr Displacement with
sign extension
@(d:16,Rn) 16 Bits
1111Sz rrr 15 0 23 15 0
Rn DP
*
1
Result
15 0 Or TP or EP
*
2
4 Register indirect 15 0 23 15 0
with pre-decrement Rn DP
*
1
Result
@–Rn Or TP or EP
*2
1011Sz rrr
Register indirect — 23 15 0
with post-increment DP
*
1
Rn
@Rn+ Rn is incremented by +1 or +2
1100Sz rrr after instruction execution.
*
3
*
4
*
5
Or TP or EP
*
2
Rn is decremented by –1 or –2
before instruction execution.
*
3
*
4
*
5
1 or 2
Displacement
–
+
+
47
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