When processing a range loop (threaded function has min and max parameters) it is the users responsability to update Thread.LoopIndex variable, if this indicator is required. Example: 

IntInterlockedIncrement(Thread.LoopIndex); 

This is because the actual loop runs within the users code. This function will return the count of all local thread iterations. The user is not allowed to increase Thread.LoopIndex 

In case of a while-loop or a for-loop without range the function will return combined number of iterations performed by all threads from the start of computation. The user is not allowed to increase Thread.LoopIndex

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