Samsung S3F84B8 - Indexed (X) Addressing Mode (Concluded)

S3F84B8_UM_REV 1.00 3 ADDRESSING MODES
3-9
3.9 INDEXED (X) ADDRESSING MODE (CONCLUDED)
Register File
OPERAND
Program Memory
or
Data Memory
Point to Working
Register Pair
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
Sample Instructions:
LDC R4, #1000H[RR2] ; The values in the program address (RR2 + 1000H)
are loaded into register R4.
LDE R4,#1000H[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
dst/src
OPCODE
Program Memory
src
OFFSET
4-bit Working
Register Address
OFFSET
+
~~
Figure 3-9 Indexed Addressing to Program or Data Memory