Renesas rl78 User Manual

 

RL78/G1A 

 

CHAPTER  3   CPU  ARCHITECTURE 

R01UH0305EJ0200  Rev.2.00 

 

 

92  

Jul 04, 2013 

 

The stack area is indirectly addressed with the stack pointer (SP) values.  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. 

Only the internal RAM area can be set as the stack area. 

 

 

Identifier Description 

− 

PUSH PSW AX/BC/DE/HL 

POP PSW AX/BC/DE/HL 

CALL/CALLT 

RET 

BRK 

RETB  

(Interrupt request generated) 

RETI 

 

Each stack operation saves or restores data as shown in Figures 3-35 to 3-40. 

 

Figure 3-35.  Example of PUSH rp 

Higher-order byte of rp

SP

F0000H

PUSH   rp

Lower-order byte of rp

SPὼ1
SPὼ2

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