ADSP-BF535 Blackfin Processor Hardware Reference
6-81
Memory
In the preceding example code, the
CSYNC
instruction ensures that
• 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
,
SSYNC
flushes any write buffers between the L1 mem-
ory and the SBIU and generates a sync request to the SBIU. The sync
request requires acknowledgement by the SBIU 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:
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...