Register Addressing Mode (R); Working Register Addressing - Samsung S3F80JB User Manual

ADDRESSING MODES

REGISTER ADDRESSING MODE (R)

In Register addressing mode, the operand is the content of a specified register or register pair (see Figure 3-1).
Working register addressing differs from Register addressing because it uses a register pointer to specify an 8-
byte working register space in the register file and an 8-bit register within that space (see Figure 3-2).
8-bit register
file address
One-Operand
Instruction
(Example)
Sample Instruction:
DEC
4-bit
Working Register
Two-Operand
Instruction
(Example)
3-2
Program Memory
dst
OPCODE
CNTR ;
Figure 3-1. Register Addressing
MSB Points to
RP0 ot RP1
Program Memory
dst src
Points to the
OPCODE
woking register
Sample Instruction:
ADD R1, R2
Figure 3-2. Working Register Addressing
Points to one
register in register
file
Value used in
instruction execution
Where CNTR is the label of an 8-bit register address
Register File
RP0 or RP1
3 LSBs
OPERAND
(1 of 8)
; Where R1 and R2 are registers in the curruntly
selected working register area.
Register File
OPERAND
Selected RP
points
to start
of working
register
block
S3F80JB