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L-Shaped RST Routing. Perform L-RST using node b as the root First step: build a separable MST Prim with w ( i,j ) = ( D ( i,j ), − | y ( i ) − y ( j )|, − max{ x ( i ), x ( j )}). First Iteration. Separable MST Construction. Separable MST Construction (cont).
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L-Shaped RST Routing • Perform L-RST using node b as the root • First step: build a separable MST • Prim with w(i,j) = (D(i,j), −|y(i) −y(j)|, − max{x(i), x(j)}) Practical Problems in VLSI Physical Design
First Iteration Practical Problems in VLSI Physical Design
Separable MST Construction Practical Problems in VLSI Physical Design
Separable MST Construction (cont) Practical Problems in VLSI Physical Design
Constructing a Rooted Tree • Node b is the root node • Based on the separable MST (initial wirelength = 32) • Bottom-up traversal is performed on this tree during L-RST routing Practical Problems in VLSI Physical Design
Partial L-RST for Node C Practical Problems in VLSI Physical Design
Partial L-RST for Node E Practical Problems in VLSI Physical Design
Partial L-RST for Node G Practical Problems in VLSI Physical Design
Partial L-RST for Node D Practical Problems in VLSI Physical Design
Partial L-RST for Node D (cont) Practical Problems in VLSI Physical Design
Partial L-RST for Node F best case Practical Problems in VLSI Physical Design
Partial L-RST for Node F (cont) best case Practical Problems in VLSI Physical Design
Processing the Root Node best case Practical Problems in VLSI Physical Design
Top-down Traversal • In order to obtain the final tree upper upper upper lower lower lower upper lower/ upper Practical Problems in VLSI Physical Design
Final Tree • Wirelength reduction • Initial wirelength − total overlap = 32 − 4 = 28 Practical Problems in VLSI Physical Design
Stable Under Rerouting • Steiner points are marked X • Wirelength does not reduce after rerouting Practical Problems in VLSI Physical Design