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Rev. 1.00, 05/04, page 44 of 544
2.7.9 Effective Address Calculation
Table 2.13 indicates how effective addresses are calculated in each addressing mode. In normal
mode, the upper 8 bits of the effective address are ignored in order to generate a 16-bit address.
Table 2.13 Effective Address Calculation (1)
No
1
Offset
1
2
4
r
op
31
0
31
23
2
3
Register indirect with displacement
@(d:16,ERn) or @(d:32,ERn)
4
r
op
disp
r
op
rm
op
rn
31
0
31
0
r
o
p
Don't care
31
23
31
0
Don't care
3
1
0
disp
31
0
31
0
31
23
31
0
Don't care
31
23
31
0
Don't care
24
24
24
24
Addressing Mode and Instruction Format Effective Address Calculation Effective Address (EA)
Register direct (Rn)
General register contents
General register contents
General register contents
General register contents
Sign extension
Register indirect (@ERn)
Register indirect with post-increment or
pre-decrement
• Register indirect with post-increment @ERn+
• Register indirect with pre-decrement @-ERn
1, 2, or 4
1, 2, or 4
Operand Size
Byte
Word
Longword
Operand is general register contents.