From behavioral description to systolic array based architectures

Aim of the new methodology proposed is to extract, from a behavioral circuit description, all information on the regularity of the computation. Array architectures optimally implement the extracted regular behavior. A high-level synthesis tool for such arrays has been defined. First, the problem of translating a hardware description language (either VHDL or Hardware C) into and internal representation useful for the exploration of different alternative architectures is afforded. Here the main problems relate to the different interpretations that can be given to an HDL description during the behavioral synthesis step. A set of design rules for writing the specifications has been identified. Then the internal design representation is studied. A hierarchical graph-based representation has been adopted which contains all information needed to identify possible regularities. The hierarchical structure is composed of a data flow graph (DFG) that holds information about data and operations performed and of a control flow graph (CFG) representing the condition clauses causing the choice of the computations to be performed. All information needed to identify the regular structures, can be derived from the DFG alone, while the information of the CFG is useful to correctly synthesize the control machine. The proposed high-level synthesis approach has been implemented into a module called Orpheus, which can be connected to the Olympus synthesis system