Gated clock design supporting method, gated clock design supporting apparatus, and computer readable memory storing gated clock design supporting program

• US 6,318,911 B1
• Filed: 03/31/1998
• Issued: 11/20/2001
• Est. Priority Date: 04/01/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kitahara, Takeshi
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): GARBOWSKI, LEIGH M
• Application Number:
  US09/052,363
• Time in Patent Office: 1,330 Days
• Field of Search: 364/488, 364/489, 364/490, 364/491, 364/468.28, 364/900, 395/500.07, 395/500.08, 395/500.1, 395/500.11, 395/500.03, 395/500.02, 395/500.09, 395/500.12, 395/500.13, 395/500.4
• US Class Current: 716/108
• CPC Class Codes: G06F 30/327 Logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist

Abstract

Information about logic circuit not clock-gated, information about enable logic for controlling clock output and information about a gating circuit are inputted through circuit information I/O portion. Enable logic timing constraint generating portion generates timing constraint to be secured for enable logic. Enable logic timing determination portion calculates a delay time in the enable logic and determines whether or not the enable logic satisfies the timing constraint based on the delay time. Clock gating execution portion, when the enable logic satisfies the timing constraint, adds a gating circuit and a circuit composed of the enable logic to a logic circuit not clock-gated so as to generate a clock-gated logic circuit. Circuit information I/O portion outputs information about the clock-gated logic circuit and timing constraint to be secured for the enable logic.

Claims

1. A gated clock design supporting method comprising the steps of:

inputting information about a logic circuit not a clock-gated, information about enable logic for controlling clock output and information about a gating circuit;

generating a timing constraint to be secured for said enable logic;

calculating a delay time in said enable logic;

determining whether or not said enable logic satisfies said timing constraint based on said delay time;

when said enable logic satisfies said timing constraint, adding said gating circuit and a circuit composed of said enable logic to said logic circuit not clock-gated so as to generate a clock-gated logic circuit; and

outputting information about said clock-gated logic circuit and said timing constraint to be secured for said enable logic.

2. A gated clock design supporting method according to claim 1, wherein said gating circuit includes a circuit for securing a normal operation for the logic circuit.

3. A gated clock design supporting method according to claim 1, further comprising the step of:

generating information about a gate a clock line of said clock-gated logic circuit.

4. A gated clock design supporting method according to claim 1, further comprising the step of outputting, when said enable logic does not satisfy the timing constraint, an error message indicating that a timing constraint error has occurred relating to an enable logic portion which does not satisfy said timing constraint.

5. A gated clock design supporting method according to claim 1, wherein information about said clock-gated logic circuit and said timing constraint to be secured for said enable logic are displayed on a display unit.

6. A gated clock design supporting method according to claim 1, wherein information about said logic circuit not clock-gated, information about said enable logic and information about said gating circuit are inputted in the form of text information through a key board.

7. A gated clock design supporting method according to claim 1, wherein information about said logic circuit not clock-gated is inputted by drawing on a screen of a display unit.

8. A gated clock design supporting apparatus comprising:

a circuit information input portion for inputting information about a logic circuit not clock-gated, information about enable logic for controlling a clock output and information about a gating circuit;

an enable logic timing constraint generating portion for generating a timing constraint to be secured for said enable logic;

an enable logic timing determination portion for calculating a delay time in said enable logic and determining whether or not said enable logic satisfies said timing constraint based on said delay time;

a clock gating execution portion for, when said enable logic satisfies said timing constraint, adding said gating circuit and a circuit composed of said enable logic to said logic circuit not clock-gated so as to generate a clock-gated logic circuit; and

a circuit information output portion for outputting information about said clock-gated logic circuit and said timing constraint to be secured for said enable logic.

9. A gated clock design supporting apparatus according to claim 8, wherein said gating circuit includes a circuit for securing a normal operation for the logic circuit.

10. A gated clock design supporting apparatus according to claim 8, further comprising:

a clock line gate information generating portion for generating information about a gate on a clock line of said clock-gated logic circuit.

11. A gated clock design supporting apparatus according to claim 8, wherein when said enable logic timing determination portion determines that said enable logic does not satisfy the timing constraint, said circuit information output portion outputs an error message indicating that a timing constraint error has occurred relating to an enable logic portion which does not satisfy said timing constraint.

12. A gated clock design supporting apparatus according to claim 8, wherein said circuit information input portion comprises a key board.

13. A gated clock design supporting apparatus according to claim 8, wherein said circuit information input portion comprises a display unit and information about said logic circuit not clock-gated is inputted by drawing on a screen of said display unit.

14. A computer-readable memory storing gated clock design supporting program, said gated clock design supporting program comprising the steps of:

inputting information about a logic circuit not clock-gated, information about enable logic for controlling a clock output and information about a gating circuit;

generating a timing constraint to be secured for said enable logic;

calculating a delay time in said enable logic;

determining whether or not said enable logic satisfies said timing constraint based on said delay time;

when said enable logic satisfies said timing constraint, adding said gating circuit and a circuit composed of said enable logic to said logic circuit not clock-gated so as to generate a clock-gated logic circuit; and

outputting information about said clock-gated logic circuit and said timing constraint to be secured for said enable logic.

15. A computer-readable memory storing gated clock design supporting program according to claim 14, wherein said gating circuit includes a circuit for securing a normal operation for the logic circuit.

16. A computer-readable memory storing gated clock design supporting program according to claim 14, further comprising the step of:

generating information about a gate on a clock line of said clock-gated logic circuit.

17. A computer-readable memory storing gated clock design supporting program according to claim 14, further comprising the step of:

when said determining step determines that said enable logic does not satisfy the timing constraint, outputting an error message indicating that a timing constraint error has occurred relating to an enable logic portion which does not satisfy said timing constraint.

18. A computer-readable memory storing gated clock design supporting program according to claim 14, wherein at said outputting step, information about said logic circuit clock-gated and said timing constraint to be secured for said enable logic are displayed on a display unit.

19. A computer-readable memory storing gated clock design supporting program according to claim 14, where at said inputting step, information about said logic circuit not clock-gated, information about said enable logic and information about said gating circuit are inputted in the form of text information through a key board.

20. A computer-readable memory storing gated clock design supporting program according to claim 14, where at said inputting step, information about said logic circuit not clock-gated is inputted by drawing on a screen of a display unit.