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ADDRESSING MODES S3C84E5/C84E9/P84E9
3-8
INDEXED ADDRESSING MODE (Continued)
Register File
OPERAND
Program Memory
or
Data Memory
Point to Working
Register Pair
(1 of 4)
LSB Selects
16-Bit
address
added to
offset
RP0 or RP1
MSB Points to
RP0 or RP1
Selected
RP points
to start of
working
register
block
dst/src
OPCODE
Program Memory
x
OFFSET
4-bit Working
Register Address
Sample Instructions:
LDC R4, #04H[RR2] ; The values in the program address (RR2 + 04H)
are loaded into register R4.
LDE R4,#04H[RR2] ; Identical operation to LDC example, except that
external program memory is accessed.
NEXT 2 Bits
Register
Pair
Value used in
Instruction
8-Bits
16-Bits
16-Bits
+
~ ~
Figure 3-8. Indexed Addressing to Program or Data Memory with Short Offset