Method and apparatus for interpreting and organizing timing specification information

• US 5,239,493 A
• Filed: 06/26/1990
• Issued: 08/24/1993
• Est. Priority Date: 06/26/1990
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Sherman, Steven K.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/544,269
• Time in Patent Office: 1,155 Days
• Field of Search: 364/578, 364/200, 364/900, 364/419, 364/488, 364/513, 371/23
• US Class Current: 716/103
• CPC Class Codes: G06F 1/04 Generating or distributing clock signals or signals derived directly therefrom
• CPC Class Codes: G06F 30/3312 Timing analysis

Abstract

A method and apparatus for converting unstructured descriptions of signal timing constraints, which can be entered by a user in a natural-language format, into unambiguous symbolic specification descriptions. The invention also generates file structures containing both the signal characteristics entered by the user and timing-constraint information that may be derived therefrom.

Claims

1. A method of reducing an unstructured electronic timing specification to a consistent format, comprising the steps of:

a. storing the unstructured specification as a character string;

b. performing sequential, character-by-character matching analysis between the character string and a set of lexicon entries having varying degrees of ambiguity, a match between an entry and the character string indicating whether the character string contains information representative of one or more classifications;

c. selecting the least ambiguous matches between the lexicon entries and the character string; and

d. based on the matching analysis, generating a symbolic description of the specification according to a known standard.

2. The method of claim 1 wherein the lexicon entries further indicate whether the character string contains information representative of one or more signals, and whether the signal is asserted true or false or is a data signal.

3. The method of claim 1 wherein the lexicon entries further indicate whether the character string contains information representative of one or more states.

4. The method of claim 1 wherein the lexicon entries further indicate whether the character string contains information representative of a clock signal.

5. The method of claim 1 further comprising the step of generating a default classification if no match is found.

6. A method of reducing to a consistent format an unstructured electronic timing specification containing information representative of at least one classification and at least one signal, comprising the steps of:

a. storing the unstructured specification as a character string;

b. performing sequential, character-by-character matching analysis between the character string and a set of lexicon entries sorted in order of increasing ambiguity until the least ambiguous match or matches are found, a match between an entry and the character string indicating that the character string contains information representative of one or more classifications;

c. based on the classification information derived from the matching analysis, generating a tentative symbolic description of the specification according to a known standard; and

d. verifying that the signal information is consistent with the classification information.

7. The method of claim 6 further comprising the step of modifying the symbolic description if the signal information is inconsistent with the classification information.

8. An apparatus for reducing an unstructured electronic timing specification to a consistent format, comprising:

a. operator-responsive input means for receiving an unstructured timing specification;

b. means, operatively coupled to the input means, for receiving therefrom the unstructured specification and storing the same as a character string; and

c. processor means for;

1) retrieving the character string;

2) performing sequential, character-by-character matching analysis between the character string and a stored set of lexicon entries having varying degrees of ambiguity, a match between a lexicon entry and the character string indicating that the character string contains information representative of one or more classifications;

3) selecting the least ambiguous match or matches between the lexicon entries and the character string;

4) based on the classification information derived from the matching analysis, generating a symbolic description of the specification according to a known standard; and

5) storing the symbolic description.

9. The apparatus of claim 8 further comprising output means for communicating the stored symbolic symbolic description.

10. The apparatus of claim 8 wherein the lexicon entries further indicate whether the character string contains information representative of one or more signals, and whether the signal is asserted true or false or is a data signal.

11. The apparatus of claim 10 wherein the lexicon entries further indicate whether the character string contains information representative of one or more states.

12. The apparatus of claim 8 wherein the lexicon entries further indicate whether the character string contains information representative of a clock signal.

13. The apparatus of claim 8 wherein the processor means is further adapted to generate and store a default classification if no match is found.

14. An apparatus for reducing to a consistent format an unstructured electronic timing specification containing information representative of at least one classification and at least one signal, the apparatus comprising:

a. operator-responsive input means for receiving an unstructured timing specification;

b. means for storing;

1) the unstructured specification as a character string;

2) a set of lexicon entries sorted in order of increasing ambiguity, each entry being indicative of one or more classifications and also corresponding to a symbolic description; and

3) information representative of the signal characteristics associated with the one or more classifications;

c. means, operatively coupled to the input means, for receiving therefrom the unstructured specification and storing the same in the storage means; and

d. processor means, operatively coupled to the storage means, for;

1) performing sequential, character-by-character matching analysis between the stored character string and the stored set of lexicon entries until the least ambiguous match or matches therebetween is found;

2) based on the matching analysis, associating the specification with the symbolic description corresponding to each matched lexicon entry, and storing the tentative description; and

3) comparing the signal characteristics associated with the classification corresponding to each matched entry with the stored signal characteristics from the specification.

15. The apparatus of claim 14 further comprising means for modifying the symbolic description if the compared characteristics are not identical.

16. The apparatus of claim 14 further comprising means for checking said lexicon entries for conflicting ambiguities.