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Table 2.8 Addressing Modes and Effective Addresses (cont)
Addressing
Mode
Mnemonic
Expression Effective Addresses Calculation Equation
PC relative
addressing
with dis-
placement
@(disp:8, PC) The effective address is the PC value plus an 8-bit
displacement (disp). disp is zero-extended, is
doubled for a word operation, and is quadrupled for
a longword operation. For a longword operation,
the lowest two bits of the PC are masked.
PC
H'FFFFFFFC
PC + disp × 2
or
PC & H'FFFFFFFC
+ disp × 4
+
2/4
×
&
*
disp
(zero-extended)
*: For longword
Word: PC +
disp × 2
Longword:
PC &
H'FFFFFFFC
+ disp × 4
PC relative
addressing
disp:8 The effective address is the PC value sign-
extended with an 8-bit displacement (disp),
doubled, and added to the PC.
PC
2
+
×
disp
(zero-extended)
PC + disp × 2
PC + disp ×
2
disp:12 The effective address is the PC value sign-
extended with a 12-bit displacement (disp),
doubled, and added to the PC.
PC
2
+
×
disp
(zero-extended)
PC + disp × 2
PC + disp ×
2
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