EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)

INTERRUPT SYNCHRONIZED AND RECOGNIZED AS PENDING

MAIN

PROGRAM FETCHES

n1

n2

LONG INTERRUPT

SERVICE ROUTINE FETCHES

(STARTS WITH A FAST INTERRUPT)

ii1

 

JSR CAN BE IN EITHER LOCATION

 

 

 

TO FORM A LONG INTERRUPT

ii2

 

 

 

 

 

 

 

 

 

 

 

 

n3

n4

ii3

ii4

INTERRUPT

ROUTINE

ii7

RTI

EXPLICIT

RETURN FROM

INTERRUPT

(SHOULD BE RTI)

PROGRAM COUNTER RESUMES OPERATION

INTERRUPTS

RE-ENABLED

 

 

(a) Instruction Fetches from Memory

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERRUPT SYNCHRONIZED AND

 

 

 

 

 

 

 

 

 

 

 

RECOGNIZED AS PENDING

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERRUPTS RE-ENABLED

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERRUPT CONTROL CYCLE 1

i

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERRUPT CONTROL CYCLE 2

 

 

i

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FETCH

n1 n2

ii1

ii2

ii3

ii4

ii5

ii6

ii7

RTI

n3

n4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DECODE

 

 

n1

n2

ii1

ii2

ii3

ii4

ii5

ii6

ii7

RTI

NOP

n3 n4

EXECUTE

n1 n2 ii1 ii2 ii3

ii4

ii5

ii6

ii7

RTI

NOP n3 n4

INSTRUCTION CYCLE COUNT

1

2

3

4

5

6

7

8

9

10

11

12

13 14 15

i= INTERRUPT

ii= INTERRUPT INSTRUCTION WORD n = NORMAL INSTRUCTION WORD

(b)Program Controller Pipeline

Figure 7-10 Long Interrupt Service Routine

7 - 30

PROCESSING STATES

MOTOROLA

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Image 157
Motorola 24-Bit Digital Signal Processor, DSP56000 manual Long Interrupt Service Routine