Extended synchronous dataflow for efficient DSP system prototyping

Though dataflow graph has been a successful input specification language for DSP system prototyping, lack of support for global states makes it unsuitable to some important applications that need global states for efficient implementation. In this paper, we propose an extension of synchronous dataflow graph to accommodate global states without side effects. Global states are accessed by a special block that piggybacks the state update request on data samples. Such an extension enlarges the domain of application where dataflow representation can be used for rapid system prototyping. Only penalty it incurs is scheduling complexity since the scheduler now considers the control dependency as well as data dependency. We show experimental results with real-life examples such as MPEG-audio decoder and 3D graphics pipeline to present the novelty and usefulness of our approach.