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Practical Problems in VLSI Physical Design A-tree Algorithm (1/13)
A-tree Routing Algorithm
Compute dx(c, F0), dy(c, F0), df(c, F0)
Practical Problems in VLSI Physical Design A-tree Algorithm (2/13)
A-tree Routing Algorithm Compute dx ( c, F 0 ), dy ( c, F 0 ), df ( - - PowerPoint PPT Presentation
A-tree Routing Algorithm Compute dx ( c, F 0 ), dy ( c, F 0 ), df ( - - PowerPoint PPT Presentation
A-tree Routing Algorithm Compute dx ( c, F 0 ), dy ( c, F 0 ), df ( c, F 0 ) We begin with root set R ( F 0 ) = { a,b,c,d,e,f } for initial forest F 0 Practical Problems in VLSI Physical Design A-tree Algorithm (1/13) Recall that mx =
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SLIDE 3
Practical Problems in VLSI Physical Design A-tree Algorithm (3/13)
Recall that … (cont)
MF = {f, i}, df = 4, mfw = i, mfs = f
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Practical Problems in VLSI Physical Design A-tree Algorithm (4/13)
Computing dx/dy/df for Node c
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Practical Problems in VLSI Physical Design A-tree Algorithm (5/13)
Computing dx/dy/df Values
Compute dx/dy/df for all other nodes
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Practical Problems in VLSI Physical Design A-tree Algorithm (6/13)
Safe Move Computation
What kind of safe moves does node a contain?
We have dx(a, F0) = ∞, dy(a, F0) = 1, df(a, F0) = 5
- Type 1: dx ≥ df and dy ≥ df
- Type 2: dx ≥ df and dy < df
- Type 3: dx < df and dy ≥ df
So a has type-2 safe move
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Practical Problems in VLSI Physical Design A-tree Algorithm (7/13)
Safe Move Computation (cont)
Compute safe moves for all nodes in F0
Type 1: dx ≥ df and dy ≥ df Type 2: dx ≥ df and dy < df Type 3: dx < df and dy ≥ df All moves are safe
- No heuristic moves necessary
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Practical Problems in VLSI Physical Design A-tree Algorithm (8/13)
Recall that …
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Practical Problems in VLSI Physical Design A-tree Algorithm (9/13)
Recall that … (cont)
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Practical Problems in VLSI Physical Design A-tree Algorithm (10/13)
Safe Move for Node a
Perform safe move for node a (type 2)
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Practical Problems in VLSI Physical Design A-tree Algorithm (11/13)
Safe Move for Node a (cont)
Updating dx/dy/df values and safe moves
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Practical Problems in VLSI Physical Design A-tree Algorithm (12/13)
Performing Remaining Safe Moves
Choose the nodes in alphabetical order
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Practical Problems in VLSI Physical Design A-tree Algorithm (13/13)
Performing Remaining Moves
Final rectilinear Steiner arborescence