Interrupting An Rep Instruction - Motorola DSP56000 Manual

INTERRUPT SYNCHRO-
NIZED AND RECOGNIZED
AS PENDING
ADDITIONAL INTERRUPTS
DISABLED DURING
FAST INTERRUPT
INTERRUPTS
RE-ENABLED
i = 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
i% = INTERRUPT REJECTED
Figure 7-13 Interrupting an REP Instruction
7 - 34
RESET PROCESSING STATE
MAIN
PROGRAM
FETCHES
n1 REP m
n2
n3
n4
n5
n6
(a) Instruction Fetches from Memory
INTERRUPT SYNCHRONIZED AND
RECOGNIZED AS PENDING
i
i%
REP n2 n3
REP NOP n2
REP NOP
1 2 3 4
(b) Program Controller Pipeline
PROCESSING STATES
REPEAT
m TIMES
i1
i2
INTERRUPTS RE-ENABLED
i
i
n4
n2 n2 n2 n3
n2 n2 n2 n2
5 6 7 8
n2
n2
n2
n2
INSTRUCTION n2
REPLACED PER
THE REP INSTRUCTION
FAST INTERRUPT
SERVICE ROUTINE FETCHES
(FROM BETWEEN P:$0000
AND P:$003F)
ii1 ii2 n5 n6
n4 ii1 ii2 n5
n3 n4 ii1 ii2
9 10 11 12
MOTOROLA