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S3C8245/P8245/C8249/P8249 ADDRESSING MODES
3-3
INDIRECT REGISTER ADDRESSING MODE (IR)
In Indirect Register (IR) addressing mode, the content of the specified register or register pair is the address of the
operand. Depending on the instruction used, the actual address may point to a register in the register file, to program
memory (ROM), or to an external memory space (see Figures 3-3 through 3-6).
You can use any 8-bit register to indirectly address another register. Any 16-bit register pair can be used to indirectly
address another memory location. Please note, however, that you cannot access locations C0H–FFH in set 1 using
the Indirect Register addressing mode.
dst
Address of Operand
used by Instruction
OPCODE
ADDRESS
8-bit Register
File Address
Point to One
Register in Register
File
One-Operand
Instruction
(Example)
Sample Instruction:
RL @SHIFT ; Where SHIFT is the label of an 8-bit register address
Program Memory Register File
Value used in
Instruction Execution
OPERAND
Figure 3-3. Indirect Register Addressing to Register File