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ADDRESSING MODES S3C9228/P9228
3-2
REGISTER ADDRESSING MODE (R)
In Register addressing mode, the operand is the content of a specified register (see Figure 3-1). Working register
addressing differs from Register addressing because it uses a 16-byte working register space in the register file
and a 4-bit register within that space (see Figure 3-2).
dst
Value used in
Instruction Execution
OPCODE
OPERAND
8-bit Register
File Address
Point to One
Rigister in Register
File
One-Operand
Instruction
(Example)
Sample Instruction:
DEC CNTR ; Where CNTR is the label of an 8-bit register address
Program Memory Register File
Figure 3-1. Register Addressing
dst
OPCODE
4-Bit
Working Register
Point to the
Woking Register
(1 of 16)
Two-Operand
Instruction
(Example)
Sample Instruction:
ADD R1, R2 ; Where R1 = C1H and R2 = C2H
Program Memory
Register File
src
4 LSBs
OPERAND
CFH
C0H
.
.
.
.
Figure 3-2. Working Register Addressing