ARM9TDMI Coprocessor Interface
4-16
Copyright © 1998, 1999 ARM Limited. All rights reserved.
ARM DDI0145B
4.7
Busy-waiting and interrupts
The coprocessor is permitted to stall, or busy-wait, the processor during the execution
of a coprocessor instruction if, for example, it is still busy with an earlier coprocessor
instruction. To do so, the coprocessor associated with the decode stage instruction
drives WAIT onto
CHSD[1:0]
. When the instruction concerned enters the execute stage
of the pipeline the coprocessor may drive WAIT onto
CHSE[1:0]
for as many cycles as
necessary to keep the instruction in the busy-wait loop.
For interrupt latency reasons the coprocessor may be interrupted while busy-waiting,
thus causing the instruction to be abandoned. Abandoning execution is done through
PASS
. The coprocessor must monitor the stage of
PASS
during every busy-wait cycle.
If it is HIGH, the instruction should still be executed. If it is LOW, the instruction should
be abandoned. Figure 4-7 shows a busy-waited coprocessor instruction being
abandoned due to an interrupt:
Figure 4-7 ARM9TDMI busy waiting and interrupts
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Содержание ARM9TDMI
Страница 1: ...Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ARM9TDMI Technical Reference Manual ...
Страница 6: ...Contents vi Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 12: ...Preface xii Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 16: ...Introduction 1 4 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 22: ...Programmer s Model 2 6 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 36: ...ARM9TDMI Processor Core Memory Interface 3 14 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 54: ...ARM9TDMI Coprocessor Interface 4 18 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 110: ...Test Issues 6 6 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 138: ...ARM9TDMI AC Characteristics 8 20 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 150: ...ARM9TDMI Signal Descriptions A 12 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 154: ...Index Index 4 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...