Fast Interrupt Service Routine - Motorola DSP56000 Manual

EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
INTERRUPT SYNCHRONIZED
AND RECOGNIZED
AS PENDING
ADDITIONAL INTERRUPTS
DISABLED DURING
FAST INTERRUPT
INTERRUPTS
RE-ENABLED
ii = INTERRUPT INSTRUCTION
n = NORMAL INSTRUCTION
INTERRUPT CONTROL CYCLE 1
INTERRUPT CONTROL CYCLE 2
FETCH
DECODE
EXECUTE
INSTRUCTION CYCLE COUNT
i = INTERRUPT
ii = INTERRUPT INSTRUCTION WORD
n = NORMAL INSTRUCTION WORD
MOTOROLA
MAIN
PROGRAM
MEMORY
n1
n2
n3
n4
(a) Instruction Fetches from Memory
INTERRUPT SYNCHRONIZED AND
RECOGNIZED AS PENDING
i
i
n1 n2
n1
1 2
(b) Program Controller Pipeline
Figure 7-8 Fast Interrupt Service Routine
PROCESSING STATES
ii1 ii2 n3 n4
n2 ii1 ii2 n3
n1 n2 ii1 ii2
3 4 5 6
ii1
ii2
INTERRUPTS RE-ENABLED
n4
n3 n4
7 8
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