Two Consecutive Fast Interrupts - Motorola DSP56000 Manual

EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
INTERRUPT SYNCHRONIZED
AND RECOGNIZED
AS PENDING
ADDITIONAL INTERRUPTS
DISABLED DURING
FAST INTERRUPT
INTERRUPTS
RE-ENABLED
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
7 - 28
MAIN
PROGRAM
MEMORY
n1
n2
n3
n4
n5
n6
n7
n8
n9
(a) Instruction Fetches from Memory
INTERRUPT SYNCHRONIZED AND
RECOGNIZED AS PENDING
6 I
cyc
i
i
n1 n2 ii1 ii2
n1 n2 ii1
n1 n2
1 2 3
(b) Program Controller Pipeline
Figure 7-9 Two Consecutive Fast Interrupts
PROCESSING STATES
FOUR INSTRUCTION
DECODES
INTERRUPTS RE-ENABLED
i
n3 n4 n5
ii2 n3 n4
ii1 ii2 n3
4 5 6 7
ii1
ii2
ii1
ii2
i
n6 ii1 ii2
n5 n6 ii1 ii2
n4 n5 n6 ii1 ii2
8 9 10 11 12
MOTOROLA