Microcomputer debug architecture and method

• US 6,502,210 B1
• Filed: 10/01/1999
• Issued: 12/31/2002
• Est. Priority Date: 10/01/1999
• Status: Expired due to Term

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: Edwards, David Alan
• Primary Examiner(s): Beausoleil, Robert
• Assistant Examiner(s): MASKULINSKI, MICHAEL C
• Application Number:
  US09/410,607
• Time in Patent Office: 1,187 Days
• Field of Search: 714/37, 714/38, 714/39, 714/47, 714/31, 717/124, 717/129, 717/130, 717/131
• US Class Current: 714/38.12
• CPC Class Codes: G06F 11/3648 using additional hardware

Abstract

A computer system including at least one central processing unit, a memory unit coupled to the at least one central processing unit, a set of watchpoints a set of watchpoints defined in the computer system, each watchpoint in the set of watchpoints including a programmable precondition register that stores a set of precondition codes, wherein the set of precondition codes is identical for each watchpoint in the set of watchpoints and a programmable action register that stores a set of action codes, wherein the set of action codes is identical for each watchpoint in the set of watchpoints, and a first comparator, having inputs coupled to the precondition register, that compares at least one precondition code in the set of precondition codes with a first data value in the computer system and provides a signal to the action register in response thereto. A method of triggering a watchpoint in a computer system is also provided.

Claims

1. A computer system comprising:

at least one central processing unit;

a memory unit coupled to the at least one central processing unit;

a set of watchpoints defined in the computer system, each watchpoint in the set of watchpoints comprising;

a programmable precondition register that stores a set of precondition codes, wherein the set of precondition codes is identical for each watchpoint in the set of watchpoints;

a programmable action register that stores a set of action codes, wherein the set of action codes is identical for each watchpoint in the set of watchpoints; and

a first comparator, having inputs coupled to the precondition register, that compares at least one precondition code in the set of precondition codes with a first data value in the computer system and provides a signal to the action register in response thereto.

2. The computer system of claim 1, wherein the comparator provides the signal to the action register if the first data value in the computer system satisfies the precondition code.

3. The computer system of claim 2, wherein the computer system responds to the signal provided to the action register and generates a signal, determined by the action code, indicating that the watchpoint has been triggered.

4. The computer system of claim 1, wherein the computer system includes hardware and software that selects which precondition codes in the set of precondition codes are active for a particular watchpoint in the set of watchpoints.

5. The computer system of claim 4, wherein the computer system includes hardware and software that selects which action codes in the set of action codes are active for a particular watchpoint in the set of watchpoints.

6. The computer system of claim 1, wherein the set of watchpoints includes types of watchpoints for operand addresses, instruction values, instruction addresses, branches, breakpoint instructions, and printf instructions.

7. The computer system of claim 1, wherein each watchpoint further comprises a programmable match register that stores at least one match code, wherein the match code stored depends on the type of watchpoint.

8. The computer system of claim 7, further comprising a second comparator, having inputs coupled to the first comparator, that responds to the first comparator, and compares the at least one match code with a second data value in the computer system and provides the signal to the action register in response thereto.

9. The computer system of claim 8, wherein the match code includes at least one of an address range, a data value, a data mask, an instruction value, an instruction mask, a branch type, and a signal external to the at least one central processing unit.

10. The computer system of claim 9, wherein the second comparator provides the signal to the action register if the second data value in the computer system matches the match code.

11. The computer system of claim 1, wherein the set of precondition codes includes a basic enable code, an address space identifier enable code, an address space identifier code, a latch enable code, a latch identifier code, an event counter enable code, an even counter identifier code, an ISA mode enable code, and a CPU supervisor mode selection code.

12. The computer system of claim 11, wherein the set of action codes includes an exception enable code, an event count decrement enable code, an event counter identifier code, a latch alter code, a latch identifier code, a performance counter increment enable code, a reset all performance counters code, a performance counter identifier code, a trace enable code, a trace message type code, an enable trace time stamp code, a trigger out enable code, and an interrupt enable code.

13. The computer system of claim 1, implemented on a single integrated circuit chip.

14. The computer system of claim 7, wherein the precondition register, the match register, and the action register occupy respective memory locations in the memory unit.

15. A computer system, comprising:

at least one central processing unit;

a memory unit coupled to the at least one central processing unit;

a set of watchpoints defined in the computer system, each watchpoint in the set of watchpoints comprising;

a first programmable storage means for storing at least one precondition code that is identical for each watchpoint in the set of watchpoints;

a second programmable storage means for storing at least one action code that is identical for each watchpoint in the set of watchpoints; and

a comparator, having inputs responsive to the first programmable storage means, that compares the at least one precondition code with a data value in the computer system and provides a signal to the second programmable storage means in response thereto.

16. A method of triggering a watchpoint in a computer system comprising at least one central processing unit and a memory unit coupled to the at least one central processing unit, the method comprising the steps of:

defining a set of watchpoints in the computer system by defining a set of precondition registers and a set of action registers;

storing a set of precondition codes in a precondition register, wherein the set of precondition codes is identical for each watchpoint in the set of watchpoints;

storing a set of action codes in an action register, wherein the set of action codes is identical for each watchpoint in the set of watchpoints;

comparing at least one precondition code in the set of precondition codes with a first data value in the computer system and providing a signal to the action register in response thereto.

17. The method of claim 16, wherein the step of comparing includes the step of providing the signal to the action register if the first data value in the computer system satisfies the precondition code.

18. The method of claim 17, further comprising the step of selecting which precondition codes in the set of precondition codes are active for a particular watchpoint in the set of watchpoints.

19. The method of claim 17, further comprising the step of selecting which action codes in the set of action codes are active for a particular watchpoint in the set of watchpoints.

20. The method of claim 16, wherein the set of watchpoints includes types of watchpoints for operand addresses, instruction values, instruction addresses, branches, breakpoint instructions, and printf instructions.

21. The method of claim 20, further comprising the step of defining a programmable match register and storing an at least one match code in the match register, wherein the match code depends on the type of watchpoint.

22. The method of claim 21, further comprising the step of comparing, after the at least one precondition code has been satisfied, the at least one match code with a second data value in the computer system.

23. The method of claim 22, wherein the signal is provided to the action register if the second data value matches the match code.

24. The method of claim 16, wherein the set of precondition codes includes a basic enable code, an address space identifier enable code, an address space identifier code, a latch enable code, a latch identifier code, an event counter enable code, an even counter identifier code, an ISA mode enable code, and a CPU supervisor mode selection code.

25. The method of claim 24, wherein the set of action codes includes an exception enable code, an event count decrement enable code, an event counter identifier code, a latch alter code, a latch identifier code, a performance counter increment enable code, a reset all performance counter code, a performance counter identifier code, a trace enable code, a trace message type code, an enable trace time stamp code, a trigger out enable code, and an interrupt enable code.

26. The method of claim 21, further comprising the step of defining the precondition register, the match register, and the action register in respective memory locations in the memory unit.