TSN credit-based shaper should be able to compensate for closed gate intervals in the corresponding time-aware shaper

[levy]

I have found another feauture, that might be interesting to be added to the current CBS implementation to match the IEEE 802.1Q-2018 standart.

In the CBS chapter 8.6.8.2 d.) on page 201 there is a note that when using CBS +TAS the idleslope has to be increased by a certain factor that compensates the closed gate intervals by a weighting factor to keep the effective datarate that the user assignes to traffic shaped by the CBS.

In the current implementation for example if the user assignes 50Mbit/s and the AVB gate is closed 50% of the time (due to TAS operation), the resulting effective data rate would be 25Mbit/s.
This could be solved by adding a weighting factor to the idleCreditGainRate.

idleCreditGainRateCompensated = idleCreditGainRate * (OperCycleTime / GateOpenTime)

Where OperCycleTime is the hyperperiod of the GCL and GateOpenTime the respective overall gate open duration per GCL cycle

Originally posted by @PhilippComet in #848 (comment)