Long Interrupt Service Routine - Motorola DSP56000 Manual

EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
INTERRUPT
SYNCHRONIZED
AND RECOGNIZED
AS PENDING
INTERRUPT CONTROL CYCLE 1
INTERRUPT CONTROL CYCLE 2
FETCH
DECODE
EXECUTE
INSTRUCTION CYCLE COUNT
i = INTERRUPT
ii = INTERRUPT INSTRUCTION WORD
n = NORMAL INSTRUCTION WORD
7 - 30
MAIN
PROGRAM
FETCHES
n1
n2
n3
n4
EXPLICIT
RETURN FROM
INTERRUPT
(SHOULD BE RTI)
(a) Instruction Fetches from Memory
INTERRUPT SYNCHRONIZED AND
RECOGNIZED AS PENDING
i
i
n1 n2 ii1 ii2 ii3
n1 n2 ii1 ii2
n1 n2 ii1
1 2 3 4 5
(b) Program Controller Pipeline
Figure 7-10 Long Interrupt Service Routine
PROCESSING STATES
LONG INTERRUPT
SERVICE ROUTINE FETCHES
(STARTS WITH A FAST INTERRUPT)
ii1
ii2
ii3
ii4
INTERRUPT
ROUTINE
ii7
RTI
INTERRUPTS RE-ENABLED
ii4 ii5 ii6 ii7 RTI
ii3 ii4 ii5 ii6 ii7
ii2 ii3 ii4 ii5
ii6
6 7 8 9 10
JSR CAN BE IN EITHER LOCATION
TO FORM A LONG INTERRUPT
PROGRAM COUNTER
RESUMES OPERATION
INTERRUPTS
RE-ENABLED
— n3 n4
RTI NOP n3 n4
RTI NOP n3 n4
ii7
11 12 13 14 15
MOTOROLA