Samsung S3F80JB - Manual (Page 55)

ADDRESSING MODES S3F80JB
3-2
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).
dst
Value used in
instruction execution
OPCODE
OPERAND
8-bit register
file address
Points to one
register 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
Points to the
woking register
(1 of 8)
Two-Operand
Instruction
(Example)
Sample Instruction:
ADD R1, R2 ; Where R1 and R2 are registers in the curruntly
selected working register area.
Program Memory
Register File
src
3 LSBs
RP0 or RP1
Selected RP
points
to start
of working
register
block
OPERAND
MSB Points to
RP0 ot RP1
Figure 3-2. Working Register Addressing