Interrupts and Sequencing
3-56
ADSP-2126x SHARC Processor Hardware Reference
registers.
lists the bits in these registers. Service
routines for arithmetic interrupts must clear the appropriate
STKYx
or
STKYy
bits to clear the interrupt. If the bits are not cleared, the interrupt is
still active after the return from interrupt (
RTI
).
Status bits in
STKYy
apply only in SIMD mode.
tion, see “SIMD (Computational) Operations” on page 2-50.
One event can cause multiple interrupts. The timer decrementing to zero
causes two timer expired interrupts to be latched,
TMZHI
(high priority)
and
TMZLI
(low priority). This feature allows selection of the priority for
the timer interrupt. Programs should unmask the timer interrupt with the
desired priority and leave the other one masked. If both interrupts are
unmasked, the DSP services the higher priority interrupt first, then it ser-
vices the lower priority interrupt.
The
IRPTL
register also supports software interrupts. When a program sets
the latch bit for one of these interrupts (
SFT0I
,
SFT1I
,
SFT2I
, or
SFT3I
),
the sequencer services the interrupt, and the DSP branches to the corre-
sponding interrupt routine. Software interrupts have the same behavior as
all other maskable interrupts.
Stacking Status During Interrupts
In an interrupt driven system, the DSP must be restored to its pre-inter-
rupt state after an interrupt is serviced. The sequencer’s status stack eases
the return from an interrupt by eliminating some interrupt service over-
head—register saves and restores.
The status stack is fifteen locations deep. The stack is full when all entries
are occupied, is empty when no entries are occupied, and is overflowed if a
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...