Trace Unit - Analog Devices ADSP-BF53x Blackfin Reference

Trace Unit

The Trace Unit stores a history of the last 16 changes in program flow
taken by the program sequencer. The history allows the user to recreate
the program sequencer's recent path.
The trace buffer can be enabled to cause an exception when full. The
exception service routine associated with the exception saves trace buffer
entries to memory. Thus, the complete path of the program sequencer
since the trace buffer was enabled can be recreated.
Changes in program flow because of zero-overhead loops are not stored in
the trace buffer. For debugging code that is halted within a zero-overhead
loop, the iteration count is available in the Loop Count registers,
.
LC1
The trace buffer can be configured to omit the recording of changes in
program flow that match either the last entry or one of the last two
entries. Omitting one of these entries from the record prevents the trace
buffer from overflowing because of loops in the program. Because
zero-overhead loops are not recorded in the trace buffer, this feature can
be used to prevent trace overflow from loops that are nested four deep.
When read, the Trace Buffer register (
Trace Unit stack, which contains as many as 16 entries. Each entry con-
tains a pair of branch source and branch target addresses. A read of
returns the newest entry first, starting with the branch destination. The
next read provides the branch source address.
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
returns the top value from the
TBUF)
Debug
and
LC0
TBUF
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