Memory-saving method and apparatus for partitioning high fanout nets

An apparatus for routing connections between pins in a net, said apparatus comprising:

• a. means for identifying elementary pairs of pins in the net, each such elementary pair defining a line;
• b. means for eliminating lines such that a planar graph is formed;
• c. means for eliminating further lines such that a spanning tree is formed, said spanning tree connecting each pin in the net;
• d. means for identifying basic elements, each basic element forming a portion of said spanning tree;
• e. means for constructing a connected cover for said net, said connected cover comprising a plurality of said basic elements;
• and
• f. routing between pins of the net in accordance with said connected cover,
• wherein said means for identifying elementary pairs comprises means for (1) determining for each pin in said net a relative x-coordinate and a relative y-coordinate, (2) constructing for each pin a combined binary coordinate as a function of the pin's relative x-coordinate and relative y-coordinate, (3) ordering the pins in accordance with their respective combined binary coordinates, (4) iteratively combining the pins based on similarity of their combined binary coordinates to form combined pins that are arranged in a hierarchical structure, and (5) iteratively expanding the combined pins to obtain the pins that were combined to form said combined pins and checking for elementary pairs at said expansion iterations.

A machine-readable storage medium containing instructions for a processor, said instructions being the steps for the processor, comprising:

• a. encoded computer means for identifying elementary pairs of pins in the net, each such elementary pair defining a line;
• b. encoded computer means for eliminating lines such that a planar graph is formed;
• c. encoded computer means for eliminating further lines such that a spanning tree is formed, said spanning tree connecting each pin in the net;
• d. encoded computer means for identifying basic elements, each basic element forming a portion of said spanning tree;
• e. encoded computer means for constructing a connected cover for said net, said connected cover comprising a plurality of said basic elements, and
• f. encoded computer means for routing between pins of the net in accordance with said connected cover,
• wherein said encoded computer means for identifying elementary pairs comprises computer encoded means for (1) determining for each pin in said net a relative x-coordinate and a relative y-coordinate, (2) constructing for each pin a combined binary coordinate as a function of the pin's relative x-coordinate and relative y-coordinate, (3) ordering the pins in accordance with their respective combined binary coordinates, (4) iteratively combining the pins based on similarity of their combined binary coordinates to form combined pins that are arranged in a hierarchical structure, and (5) iteratively expanding the combined pins to obtain the pins that were combined to form said combined pins and checking for elementary pairs at said expansion iterations.

An apparatus for routing connections between pins in a net, said apparatus comprising:

• a. means for determining for each pin in said net a relative x-coordinate and a relative y-coordinate;
• b. means for constructing for each pin a combined binary coordinate as a function of the pin's relative x-coordinate and relative y-coordinate;
• c. means for ordering the pins in accordance with their respective combined binary coordinates;
• d. means for iteratively combining the pins based on similarity of their combined binary coordinates to form combined pins that are arranged in a hierarchical structure;
• e. means for iteratively expanding the combined pins to obtain the pins that were combined to form said combined pins and identifying elementary pairs at said expansion iterations;
• and
• f. means for routing connections between pins in said net based on the elementary pairs.

A method for routing connections between pins in a net, said method comprising:

• a. determining for each pin in said net a relative x-coordinate and a relative y-coordinate;
• b. constructing for each pin a combined binary coordinate as a function of the pin's relative x-coordinate and relative y-coordinate;
• c. ordering the pins in accordance with their respective combined binary coordinates;
• d. iteratively combining the pins based on similarity of their combined binary coordinates to form combined pins that are arranged in a hierarchical structure;
• e. iteratively expanding the combined pins to obtain the pins that were combined to form said combined pins and identifying elementary pairs at said expansion iterations;
• and
• f. routing connections between pins in said net based on the elementary pairs.

A computer-readable medium storing computer-executable process steps for routing connections between pins in a net, said process steps comprising steps to:

• a. determine for each pin in said net a relative x-coordinate and a relative y-coordinate;
• b. construct for each pin a combined binary coordinate as a function of the pin's relative x-coordinate and relative y-coordinate;
• c. order the pins in accordance with their respective combined binary coordinates;
• d. iteratively combine the pins based on similarity of their combined binary coordinates to form combined pins that are arranged in a hierarchical structure;
• e. iteratively expand the combined pins to obtain the pins that were combined to form said combined pins and identify elementary pairs at said expansion iterations;
• and
• f. route connections between pins in said net based on the elementary pairs .