Illegal Instruction Interrupt Serviced By A Fast Interrupt - Motorola DSP56000 Manual

EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
INFINITE
LOOP
INTERRUPT CONTROL CYCLE 1
INTERRUPT CONTROL CYCLE 2
FETCH
DECODE
EXECUTE
INSTRUCTION CYCLE COUNT
i = INTERRUPT
ii = INTERRUPT INSTRUCTION WORD
II = ILLEGAL INSTRUCTION
n = NORMAL INSTRUCTION WORD
Figure 7-4 Illegal Instruction Interrupt Serviced by a Fast Interrupt
MOTOROLA
MAIN
PROGRAM
FETCHES
II (NOP)
n6
NO FETCH
NO FETCH
(a) Instruction Fetches from Memory
ILLEGAL INSTRUCTION INTERRUPT
n1 n2 n3 n4
n1 n2 n3
n1 n2
1 2 3 4 5
(b) Program Controller Pipeline
PROCESSING STATES
FAST INTERRUPT
SERVICE ROUTINE
FETCHES
RECOGNIZED AS PENDING
ILLEGAL INSTRUCTION INTERRUPT
RECOGNIZED AS PENDING
i
i
n5 n6 — — ii1
n4 II — — —
n3 n4 NOP — —
6 7 8 9 10
I1
I2
ii2 n5
i i 1 ii2 II
— ii1 ii2 NOP
11 12 13 14
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