Storage of (t,s,d) Triplets in OutRegistry

[pasetti]

The OutRegistry keeps track of the enable status of each (type,subtype,discriminant) triplet. For this purpose, it needs a data structure where this information is stored. The data structure must be easily searchable.

The current implementation is wasteful of memory because it allocates to each (t,s) pair N bits where N is the maximum value of the discriminant for reports of type (t,s).

Marcel has proposed the following solution:

• The user must define the maximum number of (t,s,d) triplets
• The data structure consists of an ordered sequence of (t,s,d) triplets
• The data structure is initialized with the (t,s,d) triplets which are statically known
• If a new triplet is defined dynamically or an existing one is deleted, the list is dynamically adjusted (this requires at most M operations where M is the maximum number of (t,s,d) triplets

[pasetti]

In fact, the solution outlined above would not work: owing to the way the OutRegistry interface is defined, it is necessary for it to have a statically defined list of all possible triplets.

As an alternative, we could characterize each out-going report/command through four data: (t,s,d1,d2). Here (t,s) are the type and sub-type of the report/command and d1/d2 are one of the following:

• They are both zero if the pair (t,s) has no discriminant
• They are the minimum and maximum value of the discriminant if the set of legal discriminant values is specified through a range
• They are equal and non-zero if the set of legal discriminant values are specified one by one (in that case there will be one entry for each discriminant value for a given (t,s) pair)

[pasetti]

The following solution has been implemented. Each out-going report/command in the OutRegistry is characterized through four data: (t,s,d1,d2). Here (t,s) are the type and sub-type of the report/command and d1/d2 are one of the following:

• They are both zero if the pair (t,s) has no discriminant
• They are the minimum and maximum value of the discriminant