Simulation of memory-mapped I/O

• US 7,441,254 B1
• Filed: 07/09/1997
• Issued: 10/21/2008
• Est. Priority Date: 07/09/1997
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Matthews, Gareth Christopher, Holland, Ian Michael
• Primary Examiner(s): Zhen; Li B
• Application Number:
  US08/890,643
• Time in Patent Office: 4,122 Days
• Field of Search: 707 1-205, 719/332, 717/106, 717/108
• US Class Current: 719/332
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

A converter program creates a simulated executable portion of code so that the operating system loader believes that a read only file stored on a hard drive of data consists of executable code and thereby memory-maps the read only file into virtual memory from storage. The result is that a large database may be memory-mapped into the processor virtual memory instead of the file having to be opened using standard file application program interface operations.

Claims

1. A method comprising the steps of:

converting a read-only database file into a shared library with an executable code segment, wherein the shared library includes a reference pointer to data residing in the executable code segment;

loading at least a portion of the converted read-only database file into a main memory by executing the shared library;

obtaining said reference pointer by an application; and

accessing said at least a portion of the converted read-only database file stored in the main memory based upon said reference pointer by the application.

2. The method as recited in claim 1, wherein the memory is virtual memory associated with the application running in a processor.

3. The method as recited in claim 2, wherein the converted read-only database file is memory-mapped from system storage by an operating system loader.

4. The method as recited in claim 3, wherein the converting step further comprises the step of wrapping the read only database file with executable code.

5. The method as recited in claim 4, wherein the wrapping step further comprises the step of wrapping the read only file with code headers and records in order to appear to an operating system loader as the executable code.

6. The method as recited in claim 2, wherein the processor operates in a protected mode.

7. A data processing system comprising:

circuitry for converting a read-only database file into a shared library with an executable code segment, wherein the shared library includes a reference pointer to data residing in the executable code segment;

circuitry for loading at least a portion of the converted read-only database file into a main memory by executing the shared library;

circuitry for obtaining said reference pointer by an application; and

circuitry for accessing said at least a portion of the converted read-only database file stored in the main memory based upon said reference pointer by the application.

8. The data processing system as recited in claim 7, wherein the memory is virtual memory associated with the application running in a processor.

9. The data processing system as recited in claim 7, wherein the converted read-only database file is memory-mapped from system storage by an operating system loader.

10. The data processing system as recited in claim 7, wherein the converting circuitry further comprises circuitry for wrapping the read only database file with executable code.

11. The data processing system as recited in claim 10, wherein the wrapping circuitry wraps the read only file with code headers and records in order to appear to an operating system loader as the executable code.

12. The data processing system as recited in claim 7 wherein the system includes a processor operating in a protected mode.

13. A computer program tool stored on a storage medium, comprising:

program code for converting a read-only database file into a shared library with an executable code segment, wherein the shared library includes a reference pointer to data residing in the executable code segment;

program code for loading at least a portion of the converted read-only database file into a main memory by executing the shared library;

program code for obtaining said reference pointer by an application; and

program code for accessing said at least a portion of the converted read-only database file stored in the main memory based upon said reference pointer by the application.

14. The computer program tool as recited in claim 13, wherein the memory is virtual memory associated with the application running in a processor.

15. The computer program tool as recited in claim 14, wherein the converted read-only database file is memory-mapped from system storage by an operating system loader.

16. The computer program tool as recited in claim 14, wherein the converting program code further comprises program code for wrapping the read only database file with executable code.

17. The computer program tool as recite in claim 16, wherein the program code for wrapping wraps the read only file with code headers and records in order to appear to an operating system loader as the executable code.

18. The computer program tool as recited in claim 14, wherein the processor operates in a protected mode.