DATA BASE STRUCTURE ACCESS METHOD FOR SYNTHESIZATION PROCEDURE OF LOGIC CIRCUIT DESIGNING

摘要

In a circuit design synthesis procedure in which the pointers are added to the data base to permit a path through the circuit to be followed, a qualified object is defined to be a data object that permits access expressed by a sequence (or chain) of access forms strung together. A mechanism is defined that permits access of any other object in the data base. Access forms are strung together in a given format. This structure provides an easily understandable access form and it is defined in the rule grammar. This access form can be parsed in the synthesis procedure into a nest of (LISP) program functions, which, when evaluated, will return an object in the data base. This access chain is used in the antecedent portion of the rule structure for the purpose of modifying the target objects. This access structure permits the synthesis rules to make decisions on such parameters as timing, cell size, power, wire loading, model names, etc. The rules of the synthesis procedure can be written in such a manner as to be similar to a circuit designer's rules. In addition to the access of objects, this chained access structure also permits tagging (or marking) a subset intermediate objects to be temporarily saved for use by the synthesis rules. This additional capability provides the ability to sort and partition sets of objects based on attributes and permits a synthesis procedure capable of using abstract tradeoffs.