FAMOS, an iterative improvement scheduling algorithm for the high-level synthesis of digital systems, is described. The algorithm is based on a move acceptance strategy and various selection functions defined to represent the cost of hardware resources such as functional units and registers. A main feature of the algorithm is that it can escape from local minima. The algorithm can deal with diverse design styles such as multi-cycle operations, chained operations, pipelined datapaths, pipelined functional units and conditional branches. Register costs and maximal time constraints are also considered. To efficiently represent information on the design styles, a graph model called weighted precedence graph is proposed as a general model on which the scheduling algorithm is based. Despite the iterative nature, the proposed algorithm has a polynomial time complexity. Although the optimality of the algorithm is not guaranteed, optimal solutions were obtained for several examples available from the literature.
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