ADSP-BF53x/BF56x Blackfin Processor Programming Reference
6-69
Memory
In the preceding example code, the
CSYNC
instruction ensures:
• The conditional branch (
IF CC JUMP away_from_here
) is resolved,
forcing stalls into the execution pipeline until the condition is
resolved and any entries in the processor store buffer have been
flushed.
• All pending interrupts or exceptions have been processed before
CSYNC
completes.
• The load is not fetched from memory speculatively.
The
SSYNC
instruction ensures that all side effects of previous operations
are propagated out through the interface between the L1 memories and
the rest of the chip. In addition to performing the core synchronization
functions of
CSYNC
, the
SSYNC
instruction flushes any write buffers
between the L1 memory and the system domain and generates a sync
request to the system that requires acknowledgement before
SSYNC
completes.
Speculative Load Execution
Load operations from memory do not change the state of the memory
value. Consequently, issuing a speculative memory-read operation for a
subsequent load instruction usually has no undesirable side effect. In some
code sequences, such as a conditional branch instruction followed by a
load, performance may be improved by speculatively issuing the read
request to the memory system before the conditional branch is resolved.
For example,
IF CC JUMP away_from_here
RO = [P2];
…
away_from_here:
Содержание ADSP-BF53x Blackfin
Страница 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
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Страница 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 780: ...Product Identification Register 21 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 994: ...Instructions Listed By Operation Code C 194 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...