Samsung S3C84E5 user manual Indirect Register Addressing Mode IR, @Shift

S3C84E5/C84E9/P84E9 ADDRESSING MODES

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.

	Program Memory
8-bit Register
File Address
	dst
	OPCODE
One-Operand
Instruction
(Example)

Point to One Register in Register File

Address of Operand used by Instruction

Register File

ADDRESS

Value used in Instruction Execution

OPERAND

Sample Instruction:

RL @SHIFT ; Where SHIFT is the label of an 8-bit register address

Figure 3-3. Indirect Register Addressing to Register File

3-3