Automatic designing system capable of designing a logic circuit as desired

Claim 1

An automatic designing system for designing a logic circuit comprising a plurality of functional blocks connected to one another through path nets, said automatic designing system determining a final routing layout in response to logic connection information including a circuit constraint, said logic connection information indicating connections between said functional blocks, said automatic designing system comprising: first determining means for determining an initial routing layout having at least one routing path formed by said path nets in accordance with said logic connection information; second determining means for determining a path length of each of said routing paths based on said initial routing layout; third determining means for determining a limiting length of each of said routing paths in accordance with a predetermined delay time which is determined by said circuit constraint, said limiting length being representative of a length allowed for each of said routing paths; fourth determining means for determining a difference value representative of a difference between said limiting length and said path length for each of said routing paths; selecting means for selecting the smallest value among a plurality of difference values as a selected value for each of said path nets; improving means for improving said initial routing layout into a primary routing layout in accordance with said selected value; renewing means for renewing said difference value into a renewal difference value on the basis of said initial routing layout and said primary routing layout; and replacing means for replacing said difference value by said renewal difference value to determine said final routing layout.