Method and apparatus for generating a file allocation table for a storage medium with no file allocation table using file storage information

• US 5,668,970 A
• Filed: 06/20/1994
• Issued: 09/16/1997
• Est. Priority Date: 06/20/1994
• Status: Expired due to Fees

• Current Assignee: CD Rom, U.S.A., Inc.
• Original Assignee: CD Rom, U.S.A., Inc.
• Inventors: Cowart, Larry, Cowart, Richard
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Huang, Po C.
• Application Number:
  US08/261,793
• Time in Patent Office: 1,184 Days
• Field of Search: 369/13, 369/18, 369/99, 395/416, 395/427, 395/729, 395/856, 395/857
• US Class Current: 711/206
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems

Abstract

In a typical storage medium, such as a magnetic hard disk, there is a file allocation table (FAT) stored thereon which is referenced each time the medium is accessed. Many data processing mechanisms rely on the existence of this FAT for accessing the medium. However, some storage media, such as CD-ROM'"'"'s, do not have FAT'"'"'s stored thereon. In order to properly interface FAT reliant data processing mechanisms with storage media having no FAT, file storage information is first obtained from the storage medium. Then, using this file storage information, a FAT having a format compatible with the data processing mechanisms is generated. Information from the FAT is provided to the mechanisms and, using this FAT information, the mechanisms can access information on the storage medium. Thus, even though the storage medium has no FAT, it is still accessible by FAT reliant data processing mechanisms.

Claims

1. A method for interfacing a data processing mechanism with a storage medium having no file allocation table stored thereon and having compressed data stored thereon, to directly locate the compressed data from said storage medium, comprising:

receiving a request for file allocation table information from the data processing mechanism;

gathering file storage information directly from the storage medium by reading portions of the medium;

generating dynamically in response to the request a file allocation table (FAT) using said gathered file storage information, said FAT having a format compatible with said data processing mechanism; and

providing information from said FAT to said data processing mechanism to allow said mechanism to directly access said compressed data stored on said storage medium.

2. The method of claim 1, further comprising the steps of:

storing said generated FAT into a memory for subsequent reference; and

providing the requested information from the stored FAT.

3. The method of claim 1, further comprising the steps of:

receiving a data request for compressed data from said data processing mechanism, said data request being based on information from said FAT;

translating said data request into a read request, said read request containing a reference to at least one location on said storage medium;

producing hardware calls for directly accessing the storage medium and retrieving portions of said compressed data from the location specified; and

relaying the retrieved portions of said compressed data to said mechanism.

4. A method for accessing a compressed file stored on a compact disc read only memory (CD-ROM) having no file allocation table, comprising the steps of:

receiving a request for file allocation table (FAT) information from a compression mechanism;

obtaining file storage information for said compressed file directly from said CD-ROM specifying where on said CD-ROM said compressed file is located;

generating dynamically a FAT using said file storage information, said FAT having a format which is compatible with said compression mechanism;

providing information from said FAT to said compression mechanism;

receiving a data request from said compression mechanism, said data request being based on information from said FAT;

translating said data request into a read request, said read request containing a reference to at least one location on said CD-ROM;

producing hardware calls for directly accessing the storage device and retrieving a portion of said compressed data from the location specified in the data request; and

the retrieved portion of said compressed data to said compression mechanism.

5. The method of claim 4, further comprising the step of:

storing said FAT into a memory for subsequent reference.

6. The method of claim 5, further comprising the steps of:

receiving a second request from said compression mechanism for FAT information;

accessing said memory to retrieve FAT information requested by said compression mechanism; and

providing the FAT information requested directly from said CD-ROM to said compression mechanism.

7. An apparatus for interfacing a data processing mechanism with a storage medium having no file allocation table (FAT) stored thereon to directly access one of a plurality of compressed files stored on the storage medium, comprising:

means for receiving a request from said data processing mechanism for file allocation table (FAT) information for said storage medium;

means for obtaining, in response to said request, file storage information for said storage medium directly from said storage medium specifying, for at least one file stored on said storage medium, where the file is located;

means for dynamically generating a FAT using said file storage information, said FAT having a format compatible with said data processing mechanism; and

means for providing information from said FAT to said data processing mechanism to allow said data processing mechanism to directly access information stored on said storage medium.

8. The apparatus of claim 7, further comprising:

means for receiving a second request from said data processing mechanism;

means for determining whether said second request is a request for data or for FAT information; and

means for providing further FAT information to said data processing mechanism in response to a determination that said second request is a request for FAT information.

9. The apparatus of claim 8, further comprising:

means for translating, in response to a determination that said second request is a request for data, said second request into a read request, said read request containing a reference to at least one location on said storage medium;

means for receiving data directly retrieved from at least said one location; and

means for relaying the retrieved data to said data processing mechanism.

10. The apparatus of claim 7, further comprising:

a memory for storing said FAT.

11. The apparatus of claim 7, wherein said apparatus is implemented using combinatorial logic.

12. The apparatus of claim 7, wherein said apparatus is implemented using a programmable read-only-memory.

13. The apparatus of claim 7, wherein said apparatus is implemented using a programmable logic array.

14. The apparatus of claim 7, wherein said apparatus is implemented using an application specific integrated circuit.

15. An apparatus for directly accessing a compressed file stored on a compact disc read only memory (CD-ROM) having no file allocation table stored thereon, comprising:

means for receiving a request for file allocation table (FAT) information from a compression mechanism;

means for obtaining file storage information for said compressed file directly from said CD-ROM specifying where on said CD-ROM said compressed file is located;

means for generating a FAT using said file storage information, said FAT having a format which is compatible with said compression mechanism;

means for providing information from said FAT to said compression mechanism;

means for receiving a data request from said compression mechanism, said data request being based on information from said FAT;

means for translating said data request into a read request, said read request containing a reference to at least one location on said CD-ROM;

means for receiving at least a portion of said compressed file directly retrieved from said one location; and

means for providing the retrieved portion of said compressed file to said compression mechanism.

16. The apparatus of claim 15, further comprising:

a memory for storing said FAT.

17. An information accessing system, comprising:

a storage medium having information stored thereon, said storage medium having no file allocation table (FAT) stored thereon;

a data processing mechanism, said data processing mechanism requiring FAT information in order to submit access requests to said storage medium;

an interface, said interface generating a FAT for said storage medium, providing information from said FAT to said data processing mechanism to enable said data processing mechanism to submit an access request, and translating said access request directly into a read request having a reference to at least one location on said storage medium; and

a device driver for processing said read request to retrieve information from at least said one location on said storage medium.

18. The system of claim 17, wherein said interface is implemented using combinatorial logic.

19. The system of claim 17, wherein said interface is implemented using a programmable read-only-memory.

20. The system of claim 17, wherein said interface is implemented using a programmable logic array.

21. The system of claim 17, wherein said interface is implemented using an application specific integrated circuit.