Indirect Register Addressing Mode (Ir) - Samsung S3F80P5X User Manual

S3F80P5_UM_ REV1.00

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, if implemented (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. Remember, however, that locations C0H–FFH in set 1 cannot be
accessed using Indirect Register addressing mode.
8-bit register
file address
One-Operand
Instruction
(Example)
Sample Instruction:
RL
Program Memory
dst
OPCODE
instruction execution
@SHIFT ;
Figure 3-3. Indirect Register Addressing to Register File
Points to one
register in register
file
Address of operand
used by instruction
Value used in
Where SHIFT is the label of an 8-bit register address.
ADDRESSING MODES
Register File
ADDRESS
OPERAND
3-3