Interrupt Request Acknowledge Processing Algorithm - NEC PD78052 User Manual

Figure 21-13. Interrupt Request Acknowledge Processing Algorithm
Interrupt request
reserve
Yes
among simultaneously generated
Interrupt request
reserve
Interrupt request
reserve
IF : Interrupt request flag
MK : Interrupt mask flag
PR : Priority specify flag
IE : Flag to control acknowledgment of maskable interrupt request (1 = enable, 0 = disable)
ISP : Flag to indicate the priority of interrupt currently being serviced (0 = servicing interrupt of high priority,
1 = not acknowledging interrupt request or servicing interrupt of low priority)
CHAPTER 21 INTERRUPT AND TEST FUNCTIONS
Yes (High priority)
Any high-
priority interrupt request
PR=0 interrupt
requests?
No
No
IE=1?
Yes
Vectored interrupt
servicing
Start
No
IF=1?
Yes (Interrupt Request
Generation)
No
MK=0?
Yes
PR=0?
No (Low Priority)
Any
Simultaneously
Yes
generated PR=0
interrupt requests?
No
Any
Simultaneously
Yes
generated high-priority
interrupt requests?
No
No
IE=1?
Yes
No
ISP=1?
Yes
Vectored interrupt
servicing
Interrupt request
reserve
Interrupt request
reserve
Interrupt request
reserve
Interrupt request
reserve
501