System for transparently compressing data files in a computer system

• US 5,414,850 A
• Filed: 08/23/1991
• Issued: 05/09/1995
• Est. Priority Date: 08/23/1991
• Status: Expired due to Fees

• Current Assignee: Hifn, Inc. (Maxlinear Incorporated)
• Original Assignee: STAC Electronics Incorporated
• Inventors: Whiting, Douglas L.
• Primary Examiner(s): Kriess, Kevin A.
• Assistant Examiner(s): Richey, Michael T.
• Application Number:
  US07/748,978
• Time in Patent Office: 1,355 Days
• Field of Search: 395/700, 395/200, 395/275, 395/650, 364/200, 364/900, 341/51
• US Class Current: 719/321
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30

Abstract

A data compression device driver compresses and decompresses files on a disk drive in a computer system when a user copies files from a drive letter assigned to the disk drive to a drive letter assigned to the data compression device driver. Drive parameter blocks for the disk drive and for the data compression device driver contain the assigned drive letter, disk geometry information, a rebuild flag, and a pointer to the device driver. A swapping means swaps the device driver pointers in the drive parameter blocks corresponding to the disk drive and the data compression device driver. From then on, compressed data files may be accessed transparently by using the drive letter which was originally assigned to the disk drive before swapping, which now refers to the data compression device driver.

Claims

1. A method for maintaining compressed data files on a disk drive in a computer system so that a user may access said data files as if they were uncompressed, said disk drive having a drive letter assigned by an operating system, said operating system storing with said assigned drive letter a device driver pointer to said disk drive, said method comprising:

compressing and decompressing one or more files on said disk drive with a device driver, said compressing and decompressing device driver having a drive letter assigned by said operating system, said operating system storing with said assigned drive letter for said compressing and decompressing device driver a device driver pointer to said compressing and decompressing device driver; and

swapping said device driver pointer stored with said drive letter assigned to said disk drive and said device driver pointer stored with said drive letter assigned to said compressing and decompressing device driver.

2. The method of claim 1 wherein said disk drive comprises a first portion referenced directly by said drive letter assigned to said disk drive and a second portion referenced through said compressing and decompressing device driver by said drive letter assigned to said compressing and decompressing device driver, said first portion for storing said data files uncompressed and said second portion for storing said data files compressed.

3. The method of claim 2 wherein said operating system maintains a table containing a drive parameter block for storing information regarding each of said first and said second portions of said disk drive, each of said drive parameter blocks containing said information including said assigned drive letter, said device driver pointer, disk geometry information, and a rebuild flag.

4. The method of claim 3 further comprising compressing data files before storing said data files on said second portion of said disk drive, and decompressing data files before accessing said data files from said second portion of said disk drive.

5. The method of claim 3 wherein said swapping step further comprises swapping information in addition to said device driver pointer in said drive parameter blocks corresponding to said first and second disk portions.

6. The method of claim 3 wherein said swapping step further comprises setting said rebuild flags in said drive parameter blocks corresponding to said first and second disk portions.

7. A method for maintaining compressed data files on a disk drive in a computer system so that a user may access said data files as if they were uncompressed, said disk drive having a drive letter assigned by an operating system, said method comprising:

compressing and decompressing one or more files on said disk drive with a device driver, said compressing and decompressing device driver having a drive letter assigned by said operating system; and

swapping said drive letter assigned to said disk drive and said drive letter assigned to said compressing and decompressing device driver.