Datasheet

RL78/L12 CHAPTER 3 CPU ARCHITECTURE
R01UH0330EJ0200 Rev.2.00 94
Dec 13, 2013
3.4.9 Stack addressing
[Function]
The stack area is indirectly addressed with the stack pointer (SP) contents. This addressing is automatically
employed when the PUSH, POP, subroutine call, and return instructions are executed or the register is
saved/restored upon generation of an interrupt request.
Stack addressing is applied only to the internal RAM area.
[Description format]
Identifier Description
−
PUSH PSW AX/BC/DE/HL
POP PSW AX/BC/DE/HL
CALL/CALLT
RET
BRK
RETB
(Interrupt request generated)
RETI
Figure 3-34. Example of PUSH rp
Higher-order byte of rp
SP
F0000H
PUSH rp
Lower-order byte of rp
SP – 1
SP
– 2
rp
SP
OP-code
<1>
<1>
<2>
<2>
<3>
Stack area
Memory
Stack addressing is specified <1>.
The higher-order and lower-order bytes of the pair of registers
indicated by rp <2> are stored in addresses SP – 1 and SP – 2,
respectively.
The value of SP <3> is decreased by two (if rp is the program
status word (PSW), the value of the PSW is stored in SP – 1 and
0 is stored in SP – 2).
Instruction code