Hierarchization of a priori defined dataflow subgraphs

DSP algorithms are frequently represented by dataflow graphs. These graphs serve as an abstract input specification for an implementation, either in software or hardware. While doing so, the transformation process might require a special treatment of specific subgraphs within the complete dataflow graph. A hierarchization of a subgraph appears as a replacement of the subgraph by a single vertex, representing the same functionality. The subgraph to be hierarchized might be defined by the designer manually or identified automatically, matching certain criterions. Because of the possibility of introducing a deadlock, not every hierarchization is valid. This paper presents an approach that allows to identity such deadlocking subgraphs. If an a priori defined subgraph is identified to result in a deadlock, a concept is presented that allows one to separate the subgraph into sub-subgraphs of maximum size. This allows to apply the special treatment to these sub-subgraphs and not to cancel it completely.