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Datorteknik TopologicalSort bild 1 To verify the structure Easy to hook together combinationals and flip-flops Harder to make it do what you want.

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Presentation on theme: "Datorteknik TopologicalSort bild 1 To verify the structure Easy to hook together combinationals and flip-flops Harder to make it do what you want."— Presentation transcript:

1 Datorteknik TopologicalSort bild 1 To verify the structure Easy to hook together combinationals and flip-flops Harder to make it do what you want

2 Datorteknik TopologicalSort bild 2 To verify the structure We want to check: Does my structure contain combinational loops? We want to compute: What values are being computed by the structure right now? (simulation) We will need to estimate: How fast can we clock this structure (timing analysis)

3 Datorteknik TopologicalSort bild 3 To verify the structure These three problems are all related to each other The underlying concepts are graphtheoretical We use topological sort

4 Datorteknik TopologicalSort bild 4 Answer: Impossible to be sure by “inspection” We need a procedure

5 Datorteknik TopologicalSort bild 5 The procedure Visit_line (p); Mark line For each component connected Visit_component (p) End; Visit_component (q) Mark input [save q] If all inputs marked then Calculate output For all outputs Visit_line (output) End; Main For all inputs Visit_line (value) If all lines visited then OK Else Combinatorial loop End;

6 Datorteknik TopologicalSort bild 6 Where do we begin? At the primary inputs But... What is an input to the circuit?

7 Datorteknik TopologicalSort bild 7 Inputs Here’s one! It’s a “break”. There is nothing “upstream” As far backwards as we can go &

8 Datorteknik TopologicalSort bild 8 Is there a path through this? D Q

9 Datorteknik TopologicalSort bild 9 The D- flip flop Combinationally, the D-flip flop is like this: D Q

10 Datorteknik TopologicalSort bild 10 Branch logic Sgn/Ze extend Zero ext. ALU A B

11 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

12 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B

13 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M

14 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M

15 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M

16 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M 2 M M

17 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M 2 M M 3 M M M

18 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M 2 M M 3 M M M 4 M M

19 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M 2 M M 3 M M M 4 M M 5 M M M M

20 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A 1 M M M 2 M M 3 M M M 4 M M 5 M M M M M M

21 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B 1 M M M

22 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B 1 M M M 2 M M

23 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B 1 M M M 2 M M 3 M M

24 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B 1 M M M 2 M M 3 M M 4 M M M

25 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit B 1 M M M 2 M M 3 M M 4 M M M Combinational loop

26 Datorteknik TopologicalSort bild 26 Static timing analysis Use the topological sort procedure Use max delay as component output

27 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

28 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

29 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

30 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

31 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

32 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

33 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

34 Datorteknik TopologicalSort bild 34 Compiled simulation Use the topological sort procedure Use logic function as component output

35 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

36 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

37 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

38 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

39 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A

40 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A , N= , Propagate NEG INPUT 10 0 NEG POS

41 Datorteknik TopologicalSort bild Add one Equal? Left shift one bit A


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