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US5499356A
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Method and apparatus for a multiprocessor resource lockout instruction
Assignee: RPX Corp
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Filing: 1993-12-28
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Granted: 1996-03-12
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Expires: 2013-12-28
Abstract
Abstract A method and apparatus for providing a resource lockout mechanism in a shared memory, multiprocessor system that is capable of performing both a read and write operation during the same memory operation. The load and flag instruction of the present invention can execute a read operation, followed by a write operation of a preselected flag value to the same memory location during the same memory operation. The load and flag instruction is particularly useful as a resource lockout mechanism for use in Monte Carlo applications.
Inventors
- 👤 Roger E. Eckert
- 👤 Richard E. Hessel
- 👤 Andrew E. Phelps
- 👤 George A. Spix
- 👤 Jimmie R. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:18
CPC Classifications
G; G06; G06F; G06F15/00; G06F15/76; G06F15/80; G06F15/8053; G06F15/8076; G06F15/16; G06F15/163; G06F15/173; G06F15/17356; G06F15/17368; G06F15/17381; G06F15/8092; G06F8/00; G06F8/40; G06F8/41; G06F8/43; G06F8/433; G06F8/45; G06F9/00; G06F9/06; G06F9/30; G06F9/30003; G06F9/30007; G06F9/30021; G06F9/3004; G06F9/3005; G06F9/30069; G06F9/30076; G06F9/30087; G06F9/30094; G06F9/30098; G06F9/30101; G06F9/3012; G06F9/30141; G06F9/30145; G06F9/30149; G06F9/38; G06F9/3802; G06F9/3804; G06F9/3824; G06F9/3834; G06F9/3836; G06F9/3838; G06F9/46; G06F9/52; G06F9/526; G06F2209/00; G06F2209/52; G06F2209/521
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
130 words
In a computer system a method of protecting data accessed by more than one requestor the method comprising the steps of: (a) defining a set of data values and a set of lock values, wherein the sets of data values and lock values are mutually exclusive; (b) reading a protected memory location, wherein the step of reading the protected memory location comprises atomically swapping a lock value selected from the set of lock values with information at the protected memory location; (c) determining whether the information read from the protected memory location is within the set of data values; and (d) if the information read from the protected memory location is within the set of data values, then operating on the information to form a result, else repeating steps (b)-(d).
Claim 2
Dependent Claim
130 words
In a computer system a method of protecting data accessed by more than one requestor the method comprising the steps of: (a) defining a set of data values and a set of lock values, wherein the sets of data values and lock values are mutually exclusive; (b) reading a protected memory location, wherein the step of reading the protected memory location comprises atomically swapping a lock value selected from the set of lock values with information at the protected memory location; (c) determining whether the information read from the protected memory location is within the set of data values; and (d) if the information read from the protected memory location is within the set of data values, then operating on the information to form a result, else repeating steps (b)-(d).
Claim 3
Dependent Claim
40 words
The method according to claim 1 wherein the method further comprises the step of: (e) if the data read from the protected memory location is within the set of data values, then storing the result to the protected memory location.
Claim 4
Dependent Claim
47 words
The method according to claim 1 wherein the step (a) of defining a lock value comprises determining if the protected memory location has been designated as containing a floating point number and, if so, defining one of the set of lock values to a floating point not-a-number.
Claim 5
Dependent Claim
27 words
The method according to claim 1 wherein the step (a) of defining a lock value comprises defining one of the set of lock values to hexadecimal FFF4000000000000.
Claim 6
Dependent Claim
22 words
The method according to claim 1 wherein the step (d) of repeating comprises waiting a period of time before executing step (b).
Claim 7
Dependent Claim
160 words
A resource-lockout apparatus for a computer system having a shared memory, wherein a plurality of requestors may each request access to a selected memory location in the shared memory, and wherein a set of data values and a set of defined flag values are defined, wherein the set of data values and the set of defined flag values are mutually exclusive, the resource-lockout apparatus comprising: (a) means for atomically swapping a lock value selected from the set of lock values with information at the protected memory location; (b) means for determining whether the information read from the protected memory location is within the set of data values; (c) means for operating on the information to form a result if the information read from the protected memory location is within the set of data values; and (d) means for transferring control to means (a) if the information read from the protected memory location is not within the set of data values.
Claim 8
Dependent Claim
160 words
A resource-lockout apparatus for a computer system having a shared memory, wherein a plurality of requestors may each request access to a selected memory location in the shared memory, and wherein a set of data values and a set of defined flag values are defined, wherein the set of data values and the set of defined flag values are mutually exclusive, the resource-lockout apparatus comprising: (a) means for atomically swapping a lock value selected from the set of lock values with information at the protected memory location; (b) means for determining whether the information read from the protected memory location is within the set of data values; (c) means for operating on the information to form a result if the information read from the protected memory location is within the set of data values; and (d) means for transferring control to means (a) if the information read from the protected memory location is not within the set of data values.
Claim 9
Dependent Claim
19 words
The apparatus according to claim 6 wherein one of the set of lock values is a floating point not-a-number.
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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) | 1999-03-12 | 1999-09-11 | 2000-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-12 | 2003-09-11 | 2004-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-12 | 2007-09-11 | 2008-03-12 | $7700.00 | Window Closed / Lapsed |