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Chapter 2 Addressing Modes
+0 dsp +7
Memory
label
Program counter relative
label
Base address
dsp
dsp
dsp
label
label
Memory
Base address
If the dsp value is positive
2.4 Special Instruction Addressing
If the dsp value is negative
• If the jump length specifier (.length)
is (.S)...
the base address plus the value
indicated by displacement (dsp)—
added not including the sign bits—
constitutes the effective address.
This addressing can be used in JMP
instruction.
• If the jump length specifier (.length) is
(.B) or (.W)...
the base address plus the value indicated
by displacement (dsp)—added including
the sign bits—constitutes the effective
address.
However, if the addition resulted in
exceeding 00000
16- FFFFF16, the bits
above bit 21 are ignored, and the address
returns to 0000016 or FFFFF16.
This addressing can be used in JMP and
JSR instructions.
*1 The base address is the (start address of instruction + 2).
*2 The base address varies with each instruction.
If the specifier is (.B), -128 ≤ dsp ≤ +127
If the specifier is (.W), -32768 ≤ dsp ≤ +32767
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