Renesas rl78 User Manual
RL78/G1A
CHAPTER 3 CPU ARCHITECTURE
R01UH0305EJ0200 Rev.2.00
79
Jul 04, 2013
3.3 Instruction Address Addressing
3.3.1 Relative addressing
[Function]
Relative addressing stores in the program counter (PC) the result of adding a displacement value included in the
instruction word (signed complement data:
−128 to +127 or −32768 to +32767) to the program counter (PC)’s value
(the start address of the next instruction), and specifies the program address to be used as the branch destination.
Relative addressing is applied only to branch instructions.
Figure 3-13. Outline of Relative Addressing
OP code
PC
DISPLACE
8/16 bits
Instruction code
3.3.2 Immediate addressing
[Function]
Immediate addressing stores immediate data of the instruction word in the program counter, and specifies the
program address to be used as the branch destination.
For immediate addressing, CALL !!addr20 or BR !!addr20 is used to specify 20-bit addresses and CALL !addr16 or
BR !addr16 is used to specify 16-bit addresses. 0000 is set to the higher 4 bits when specifying 16-bit addresses.
Figure 3-14. Example of CALL !!addr20/BR !!addr20
OP code
PC
Low Addr.
High Addr.
Seg Addr.
Instruction code
Figure 3-15. Example of CALL !addr16/BR !addr16
OP code
PC
S
Low Addr.
High Addr.
PC
PC
H
PC
L
0000
Instruction code