Motorola DSP96002 - Manual (Page 145)

MOTOROLA DSP96002 USER’S MANUAL 8 - 5
*
Int ctl cyc1 i i
Int ctl cyc2 i i
Fetch n3 n4 ii1 ii2 n4 n5 n6 n7 ii3 ii4 n8
Decode n2 n3 n4 f1 f2 n4 -- n6 n7 f3 f4
Execute n1 n2 n3 NOP f1 f2 n4 -- n6 n7 f3
f = fast interrupt instruction word (non-control-flow-change)
i = interrupt
ii = interrupt instruction word
n = normal single word instruction
n4 = 2-word instruction
n5 = 2nd word of n4
* subsequent interrupts are enabled at this time
Figure 8-2. Example of Aborting a Two Word Instruction Fast Interrupt
*
Int ctl cyc1 i i
Int ctl cyc2 i i
Fetch n3 n4 ii1 ii2 n5 n6 n7 n8 ii3 ii4 n9
Decode n2 n3 n4 f1 f2 n5 n6 n7 -- f3 f4
Execute n1 n2 n3 n4 f1 f2 n5 n6 n7 -- f3
f = fast interrupt instruction word (non-control-flow-change)
i = interrupt
ii = interrupt instruction word
n = normal instruction word
n7 = 2-word instruction
n8 = 2nd word of n7
* subsequent interrupts are enabled at this time
Figure 8-3.
Example Of The Case Of Four Instructions Between Consecutive Vectors
8.3.2.2 Long Interrupt Instruction Execution
A jump to subroutine instruction within a fast interrupt routine forms a long interrupt routine. One-word or
two-word jump to subroutine instructions may be used to form a long interrupt routine. The one-word jump
to subroutine may be located in either the first or second interrupt vector location. If a conditional one-word
jump to subroutine is located in the first interrupt vector location, the instruction in the second vector loca-
tion will be ignored if the jump condition is true but executed if the jump condition is false. If the one-word
jump to subroutine is located in the second interrupt vector location, the instruction in the first vector loca-
tion will be fetched and executed before executing the jump to subroutine. Execution of a long interrupt
routine always follows the following rules:
1. During execution of the jump to subroutine instruction, when it occurs in the first or second
interrupt vector location, the following actions occur:
1. The PC and SR are stacked.