RESET PROCESSING STATE

INTERRUPTSYNCHRO-

NIZEDANDRECOGNIZED ASPENDING

ADDITIONALINTERRUPTS DISABLEDDURING FASTINTERRUPT

INTERRUPTS

RE-ENABLED

MAIN

 

 

PROGRAM

 

 

FETCHES

 

 

 

 

n2

 

REPEAT

n2

 

n2

n1 REP m

m TIMES

n2

 

n2

 

INSTRUCTION n2

n3

 

REPLACED PER

 

THE REP INSTRUCTION

 

 

n4

 

 

n5

 

 

n6

 

i1

 

 

i2

 

 

FAST INTERRUPT

 

 

SERVICE ROUTINE FETCHES

 

 

(FROM BETWEEN P:$0000

 

 

AND P:$003F)

i= INTERRUPT INSTRUCTION n = NORMAL INSTRUCTION

(a) Instruction Fetches from Memory

INTERRUPT SYNCHRONIZED AND

RECOGNIZED AS PENDING

INTERRUPTS RE-ENABLED

INTERRUPT CONTROL CYCLE 1

i

i

 

 

 

INTERRUPT CONTROL CYCLE 2

i%

i

FETCH

REP

n2

n3

n4

ii1

ii2

n5

n6

DECODE

REP NOP n2

n2

n2

n2

n3

n4

ii1

ii2

n5

EXECUTE

REP NOP

n2

n2

n2

n2

n3

n4

ii1

ii2

INSTRUCTION CYCLE COUNT

1

2

3

4

5

6

7

8

9

10

11

12

i= INTERRUPT

ii= INTERRUPT INSTRUCTION WORD n = NORMAL INSTRUCTION WORD i% = INTERRUPT REJECTED

(b)Program Controller Pipeline

Figure 7-13 Interrupting an REP Instruction

7 - 34

PROCESSING STATES

MOTOROLA

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Image 161
Motorola 24-Bit Digital Signal Processor, DSP56000 manual Interrupting an REP Instruction