LAPIS Semiconductor ML610421, Руководство пользователя, Страница: 90 / 437

ML610Q421/ML610Q422/ML610421 User’s Manual
Chapter 5 Interrupts (INTs)
5 – 21
A-2: When a subroutine is called by the program in executing an interrupt routine
A-2-1: When multiple interrupts are disabled
•
Processing immediately after the start of interrupt routine execution
Specify the “PUSH LR” instruction to save the subroutine return address in the stack.
•
Processing at the end of interrupt routine execution
Specify “POP LR” immediately before the RTI instruction to return from the interrupt processing after
returning the subroutine return address to LR.
A-2-2: When multiple interrupts are enabled
•
Processing immediately after the start of interrupt routine execution
Specify “PUSH LR, ELR, EPSW” to save the interrupt return address, the subroutine return address, and the
EPSW status in the stack.
•
Processing at the end of interrupt routine execution
Specify “POP PC, PSW, LR” instead of the RTI instruction to return the saved data of the interrupt return
address to PC, the saved data of EPSW to PSW, and the saved data of LR to LR.
Example of description: A-2-2
Intrpt_A-2-2: ; Start
PUSH ELR, EPSW,
LR
; Save ELR, EPSW, LR at
the beginning
EI ; Enable interrupt
: Sub_1: ;
: DI ; Disable interrupt
: :
:
BL Sub_1 ; Call subroutine Sub_1 :
: RT ; Return PC from LR
POP PC, PSW, LR ; Return PC from the stack ; End of subroutine
; Return PSW from the stack
; Return LR from the stack
; End