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S3C9228/P9228 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.
8-Bit Register
File Address
One-Operand
Instruction
(Example)
dst
Address of Operand
used by Instruction
OPCODE
ADDRESS
Point to One
Rigister in Register
File
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