4.11.2. Alignment synchronization
A-sync packets provide alignment synchronization. The PTM
generates an A-sync packet when it is initialized, and then generates
additional A-sync packets periodically. A trace decompressor uses
the A-sync packets to achieve:
Byte
alignment. This ensures the decompressor can determine the start
of each byte of trace.
Packet boundary synchronization. This ensures the
decompressor does not attempt to start decompression in the middle
of a multi-byte packet.
The PFT protocol guarantees that the first byte (8 bits) after
the last bit of an A-sync packet is the first byte of a new packet.
Therefore, detecting an A-sync packet achieves byte alignment and
packet boundary synchronization.
For details of the A-sync packet see A-sync, alignment
synchronization packet.
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