Loops and Sequencing
3-34
ADSP-2126x SHARC Processor Hardware Reference
loop. If there is no executing loop, the value of
CURLCNTR
is 0xFFFF FFFF
after the pop.
Writing
CURLCNTR
does not cause a stack push. If a program writes a new
value to
CURLCNTR
, the program changes the count value of the loop cur-
rently executing. When a
DO
/
UNTIL
LCE
loop is not executing, writing to
CURLCNTR
has no effect. Because the processor must use
CURLCNTR
to per-
form counter-based loops, some restrictions relating to how a program can
write
CURLCNTR
apply. See
“Restrictions on Ending Loops” on page 3-27
for more information.
The next-to-top entry in the loop counter stack (
LCNTR
) is the location on
the stack that takes effect on the next loop stack push. To set up a count
value for a nested loop without changing the count for the currently exe-
cuting loop, a program writes the count value to
LCNTR
.
A value of zero in
LCNTR
causes a loop to execute 2
32
times.
A
DO/UNTIL
LCE
instruction pushes the value of
LCNTR
onto the loop count
stack, making that value the new
CURLCNTR
value.
demonstrates
this process for a set of nested loops. The previous
CURLCNTR
value is pre-
served one location down in the stack. If a program reads the
LCNTR
when
the loop counter stack is full, the stack returns invalid data. When the
loop counter stack is full, the stack discards any data written to
LCNTR
.
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...