Abstract: A method for executing operations upon a linked data structure having at least one element such that the time during which the linked data structure is locked is reduced. The method includes performing a first set of operation tasks in a first phase, the first set of operation tasks being operable to effect a first set of element state transitions. A second set of operation tasks is developed in the first phase, the second set of operation tasks being operable to effect a second set of element state transitions, the second set of element state transitions being distinct from the first set of element state transitions. The second set of operation tasks is performed in a second phase. The method finds particular implementation in the rebalancing of tree data structures.

Abstract: A system and method for performing an operation within limits upon a shared value stored in an actual value location. The method provides a plurality of memory locations, two of the memory locations being first and second reservation memory locations, and two of the memory locations being limit memory locations containing limit values. An operand is obtained and the operation is performed upon an affected reservation register using the operand. A resulting value is compared to the limit values in the limit memory locations and if the resulting value is not within the values in the limit memory locations, an inverse operation is performed to restore the affected reservation register and a failure is reported. Else the operation is performed to update the actual value location, the operation is performed to update an unaffected reservation register, and a success is reported.

Abstract: A method for executing operations upon a linked data structure having at least one element such that the time during which the linked data structure is locked is reduced. The method includes performing a first set of operation tasks in a first phase, the first set of operation tasks being operable to effect a first set of element state transitions. A second set of operation tasks is developed in the first phase, the second set of operation tasks being operable to effect a second set of element state transitions, the second set of element state transitions being distinct from the first set of element state transitions. The second set of operation tasks is performed in a second phase. The method finds particular implementation in the rebalancing of tree data structures.

Abstract: A method for enhancing concurrency in a multiprocessor computer system is described. Various tasks in a computer system communicate using commonly accessible mailboxes to access valid data from a location in the mailbox. A task holding the valid data places that data in a mailbox, and other tasks read the valid data from the mailbox. The task that inputs the valid data into the mailbox is caused to notify other tasks addressing the mailbox that the valid data is contained therein. Thus, no central coordination of mailbox access is required. Further, busy waits for valid data are minimized and the ressources of tasks and processors are used more efficiently. By coordinating several lists associated with each mailbox, conflicts in accessing data and delays in obtaining data are also minimized.

Abstract: A system and method for executing computational operations upon elements of a data structure. The method includes determinations of the commutativity of the computational operations. If the computational operations are determined to be commutative the computational operations are executed regardless of order.

Abstract: A lock-free list for use with a computer system. The lock-free list includes a list storage structure comprising at least two sublists, each of a plurality of list elements being sequentially assignable to one of the at least two sublists in such manner that a plurality of assigned list elements is partitionable across the at least two sublists, an indicator for indicating whether each of the at least two sublists is empty or in use, an indicator for indicating whether a list element is being removed from each of the at least two sublists, an indicator for recording an order of the at least two sublists into which the plurality of assigned list elements are assigned, and an indicator for recording for each of the at least two sublists, a write address location and a read address location.

Abstract: A method for pushing a list element onto a linked list without locking the linked list. The linked list includes a head element having a pointer to a first list element. The method includes the steps of (a) reading the pointer, (b) writing the pointer to a list element address field, and (c) atomically comparing the pointer written to the list element address field with the pointer to the first list element and exchanging an address of the list element for the pointer if the values compared are equal, else repeating steps (a) through (c). A non-blocking pop operation is also disclosed.

Abstract: A lock-free list for use with a computer system. The lock-free list includes a list storage structure comprising at least two sublists, each of a plurality of list elements being sequentially assignable to one of the at least two sublists in such manner that a plurality of assigned list elements is partitionable across the at least two sublists, an indicator for indicating whether each of the at least two sublists is empty or in use, an indicator for indicating whether a list element is being removed from each of the at least two sublists, an indicator for recording an order of the at least two sublists into which the plurality of assigned list elements are assigned, and an indicator for recording for each of the at least two sublists, a write address location and a read address location.

Abstract: A system and method for performing an operation within limits upon a shared value stored in an actual value location. The method provides a plurality of memory locations, two of the memory locations being first and second reservation memory locations, and two of the memory locations being limit memory locations containing limit values. An operand is obtained and the operation is performed upon an affected reservation register using the operand. A resulting value is compared to the limit values in the limit memory locations and if the resulting value is not within the values in the limit memory locations, an inverse operation is performed to restore the affected reservation register and a failure is reported. Else the operation is performed to update the actual value location, the operation is performed to update an unaffected reservation register, and a success is reported.

Abstract: In the present invention, a full look-up table for 32 bits is disclosed. The look-up table is for interfacing the output of the memory frame buffer with a color monitor in a digital, color graphics display apparatus. The look-up table duplicates some of the output lines of the memory frame buffer as the input to the look-up table. The input lines and the duplicated input lines are supplied as address input lines to a first memory bank. The output of the first memory bank at the address selected by the input lines are received by a second memory bank as the address input lines therefor. The output of the second memory bank is supplied yet to the third memory bank as the address input lines thereto. The output of the third memory bank forms the output of the look-up table.