US6535867B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
System and method for accessing external memory using hash functions in a resource limited device
Assignee: CELSIUS RESEARCH Ltd
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Filing: 1999-11-01
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Granted: 2003-03-18
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Expires: 2019-11-01
Abstract
Abstract A system and method that computes a hash function based upon the file name, e.g. a URI, that is to be identified in a look-up table stored in external memory. The hash value is multiplied by a first multiplier. The result is used as a pointer to a lookup table that is stored in external memory. The present invention avoids the need to perform string comparisons or to store any file names or addresses on the server.
Inventors
- 👤 Christopher J. F. Waters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:09
CPC Classifications
G; G06; G06F; G06F16/00; G06F16/10; G06F16/90; G06F16/901; G06F16/9014; Y; Y10; Y10S; Y10S707/00; Y10S707/99931; Y10S707/99932; Y10S707/99941; Y10S707/99942
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
A computer based method for accessing data files in an external memory without requiring a data file path name to be stored on internal memory, comprising the steps of: receiving a data file path name; determining a hash value of said data file path name; indexing an index block in an external memory using an index address corresponding to said hash value; identifying an offset value stored at said index address; and retrieving a file corresponding to said data file path name by accessing an offset address corresponding to said offset value.
Claim 2
Dependent Claim
92 words
A computer based method for accessing data files in an external memory without requiring a data file path name to be stored on internal memory, comprising the steps of: receiving a data file path name; determining a hash value of said data file path name; indexing an index block in an external memory using an index address corresponding to said hash value; identifying an offset value stored at said index address; and retrieving a file corresponding to said data file path name by accessing an offset address corresponding to said offset value.
Claim 3
Dependent Claim
19 words
The method of claim 1 further comprising the step of verifying the retrieved file by a collision resolution technique.
Claim 4
Dependent Claim
39 words
The method of claim 1 further comprising determining a second hash value based on said data file path name and comparing said second hash value to a value stored within said file corresponding to said data file path name.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein the external memory comprises an EEPROM.
Claim 6
Dependent Claim
15 words
The method of claim 1 wherein the internal memory comprises a static random access memory.
Claim 7
Dependent Claim
26 words
The method of claim 1 wherein determining the hash value of said data file path name produces a value within a predetermined range of hash values.
Claim 8
Dependent Claim
27 words
The method of claim 6 wherein the predetermined range of hash values corresponds directly to a single block of consecutive memory address locations in the external memory.
Claim 9
Dependent Claim
26 words
The method of claim 6 wherein the predetermined range of hash values corresponds to one or more blocks of memory address locations in the external memory.
Claim 10
Dependent Claim
35 words
The method of claim 1 wherein determining the hash value of said data file path name comprises calculating an unsigned 8-bit sum of the ASCII values of the characters in said data file path name.
Claim 11
Dependent Claim
43 words
The method of claim 1 wherein determining the hash value of said data file path name comprises calculating an unsigned 8-bit sum of the ASCII values of the characters in said data file path name and multiplying this sum by a multiplicative factor.
Claim 12
Dependent Claim
13 words
The method of claim 1 wherein the computer is a resource limited computer.
Claim 13
Dependent Claim
104 words
A computer based apparatus for accessing data files in an external memory without requiring a data file path name to be stored in internal memory, comprising: receiving means for receiving a data file path name; hashing means for determining a hash value of said data file path name; indexing means for indexing an index block in an external memory using an index address corresponding to said hash value; identifying means for identifying an offset value stored at said index address; and retrieving means for retrieving a file corresponding to said data file path name by accessing an offset address corresponding to said offset value.
Claim 14
Dependent Claim
104 words
A computer based apparatus for accessing data files in an external memory without requiring a data file path name to be stored in internal memory, comprising: receiving means for receiving a data file path name; hashing means for determining a hash value of said data file path name; indexing means for indexing an index block in an external memory using an index address corresponding to said hash value; identifying means for identifying an offset value stored at said index address; and retrieving means for retrieving a file corresponding to said data file path name by accessing an offset address corresponding to said offset value.
Claim 15
Dependent Claim
20 words
The computer based apparatus of claim 12 , further comprising verifying means for verifying the identity of the retrieved file.
Claim 16
Dependent Claim
37 words
The computer based apparatus of claim 12 wherein determining a hash value of said data file path name comprises calculating an unsigned 8-bit sum of the ASCII values of the characters in said data file path name.
Claim 17
Dependent Claim
45 words
The computer based apparatus of claim 12 wherein determining a hash value of said data file path name comprises calculating an unsigned 8-bit sum of the ASCII values of the characters in said data file path name and multiplying this sum by a multiplicative factor.
Claim 18
Dependent Claim
14 words
The computer based apparatus of claim 12 wherein the external memory comprises an EEPROM.
Claim 19
Dependent Claim
17 words
The computer based apparatus of claim 12 wherein the internal memory comprises a static random access memory.
Claim 20
Dependent Claim
15 words
The computer based apparatus of claim 12 wherein the computer is a resource limited computer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-03-17 | 2006-09-16 | 2007-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-03-17 | 2010-09-16 | 2011-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-03-17 | 2014-09-16 | 2015-03-18 | $7700.00 | Window Closed / Lapsed |