High-level synthesis of DSP datapaths by global optimisation of variable lifetimes

COBRA (Column-Oriented Butted Regular Architecture) is a behavioural high-level synthesis tool for datapath-dominated applications. It globally optimises the synthesised datapath by performing the scheduling and allocation tasks simultaneously. COBRA uses a bit-sliced target architecture and layout style which, when compared with conventional approaches, significantly reduces the area of the final datapaths. The synthesis problem is formulated as an optimisation problem on the configuration of variable lifetimes when mapped into a 3D `datapath space´. The configuration of the data in the datapath space implies the structure required to achieve the data configuration and hence the datapath. Simulated annealing is used to optimise the solution. A description is given of the target architecture, the mapping of the input description into the datapath space, the optimisation of the data configuration in the datapath space, and the post-processing operations. Results for a number of examples are presented