CoreSight Program Flow Trace Architecture Specification: 3.5. Context ID comparators

3.5. Context ID comparators

It is implementation defined whether a PTM implements Context ID comparators. If it does, it implements:

between one and three Context ID comparators
a Context ID Comparator Value Register for each comparator
a single Context ID Comparator Mask Register.

Each Context ID Comparator Value Register can hold a Context ID value, for comparison with the current Context ID. The Context ID Comparator Mask can hold a mask value, that is used to mask all Context ID comparisons. If you program the Context ID Comparator Mask Register to zero then no mask is applied to the Context ID comparisons. For more information, see About the Context ID comparator registers.

The PTM uses the Context ID comparators in two ways:

You can make any address comparison conditional on the Context ID also matching, by programming the Address Comparator Access Type register with the number of the Context ID comparator to use.
Each Context ID comparator provides an event resource. At each waypoint, the PTM compares the current Context ID with each of the Context ID comparators. If there is a match then the corresponding event resource is TRUE, otherwise it is FALSE. These values are held until the PTM processes the next waypoint.

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