Method and system for logic change in an automatic logic synthesis system

A system for logic change in an automatic logic synthesis system, said automatic logic synthesis system comprising:

• storage means for storing higher-rank descriptions, which define a logic device in terms of expressions of higher abstraction, and for storing lower-rank descriptions, which define the logic device in terms of expressions of lower abstraction;
• and
• data processing means including the automatic logic synthesis means for synthesizing from higher-rank description data stored in said storage means, lower-rank description unit data and for storing said synthesized data in said storage means;
• said storage means including:
• an area for storing first identifiers each of which indicates the presence of a description change of the corresponding higher-rank description unit data, and an area for storing second-identifiers each of which indicates the presence of a description change of the corresponding lower rank description unit data;
• said data processing means including:
• higher-rank description edit means for setting the first identifier of changed description unit data at the change of the higher-rank description,
• lower-rank description edit means for setting the second identifier of changed description unit at the change of the lower-rank description directly made without any synthesis process from the higher-rank description, and
• automatic logic synthesis means for originating new lower-rank description unit data from the higher-rank description unit whose first identifier is set, in the automatic logic synthesis after the higher-rank description change, whereupon on condition that the second identifier of the current lower-rank description unit data corresponding to the new lower-rank description unit data is not set, said means registers the new lower-rank description unit data as lower-rank description unit data, and on condition that the second identifier of the current lower-rank description unit data is set, said means merges the new lower-rank description unit data and the current lower-rank description unit data and registers a merged result as lower-rank description unit data.