Altera Corporation

John Tse

Fung Fung Lee

David Wolk Mendel

Neville Carvalho

Chee Seng Tan

Chai Sia Tan

Elden Chau

Methods and apparatus are described for efficiently performing EDA processing to arrive at a hardware definition for a varying fraction of a large circuit design. EDA processing is conducted targeting a pseudo hardware device with sufficient capacity to embody circuitry for the varying fraction, but substantially less than the true hardware target. The novel methods and apparatus may be beneficially employed to produce reconfiguration information for circuits that include programmable logic, for example.

Method and apparatus for circuit block reconfiguration EDA

A memory configuration circuit is provided. The memory configuration circuit may be integrated into a programmable logic device (PLD) and as such, may be used to configure and reconfigure specific elements in the PLD. The memory configuration circuit includes a comparator circuit and a counter. The comparator circuit is coupled to receive two data words from two different memory configuration sources. The comparator circuit compares the two data words received before writing one of the data words to a configuration memory. One of the data words may be written to the configuration memory if the two data words compared are not equal. The counter increments the address of the memory configuration sources so that a next data word can be processed after the current data word is processed.

Integrated circuit reconfiguration techniques

Systems and methods of hierarchical circuit partitioning are provided. More specifically, the invention utilizes a sliding window which is moved over portions of a hierarchical structure representing a programmable logic device. The window includes some but not all containers of the hierarchical structure so that logic cells may be partitioned within the window. After the logic cells are partitioned in the window, the window is moved to a different location of the hierarchical structure. By utilizing a sliding window, the invention is able to recursively partition logic cells into portions of the hierarchical structure which increases the overall efficiency of the partitioning.

Hierarchical circuit partitioning using sliding windows

A method for partitioning a group of cells in a network into a set of disjoint blocks of cells. The network is represented by a hierarchical graph with each level representing a hierarchy of resources, leaf nodes representing the blocks of cells, and edges representing interconnections between resources. A gain matrix is formed by combining a gain vector for each level of hierarchy for each possible move. Cells are moved between leaf nodes based on the gain matrix computed.

Gain matrix for hierarchical circuit partitioning

A technique is disclosed for efficiently placing logic cells from an electronic design during an incremental recompile. This is accomplished by fixing in place as many logic cells as possible during the recompile procedure. To understand how this works, recognize than an 'original electronic design' has already been fully compiled. Now, a user has made one or more changes to the original electronic design to produce a 'changed electronic design.' The disclosed technique fits the changed electronic design, during incremental recompile, without effecting too much of the logic previously fit during compilation of the original electronic design. Initially, a compiler attempts to fit logic cells of the changed portion of the electronic design onto available logic elements of the hardware device while confining logic cells from the unchanged portion of the changed electronic design to their original positions. If this fails, the compiler allows logic cells from the unchanged portion of the changed electronic design to shift by a limited amount to other logic elements within the target hardware device. At first, this shifting is fairly constrained in order to preserve as much of the original compilation's placement as possible. However, if fitting can not be accomplished under these constraints, gradually the constraints are lifted, until a fit is achieved.

Fitting for incremental compilation of electronic designs

Improved circuit partitioning methods are provided which combine the advantage of multiple starting positions of the random initial placement approach with the advantage of optimal starting positions of the greedy initial placement approach, by starting with greedy initial placement and modifying partitioning constraints on subsequent passes so that each pass begins in a new position, In addition, the partitioning goals of interconnection minimization and resource utilization efficiency may be prioritized according to a design goal by manipulating the manner in which partitioning constraints are changed during each partitioning pass. Furthermore a user may adjust the weight of the benefits for eliminating existing interconnections and the weight of the penalties for adding new interconnections in accordance with a design goal.

Methods for partitioning circuits in order to allocate elements among

A programmable logic array integrated circuit has a plurality of logic modules, each of which is programmable to perform any of several logic functions. One such function is the performance of one place of binary addition yielding a sum out signal and a carry out signal. In addition to a dedicated carry chain which conveys the carry out signal of each logic module to the carry in input of another predetermined logic module, circuitry is provided for allowing the carry out signal of each logic module to be alternatively routed through the more general interconnection circuitry of the device. This increases the flexibility of routing of the carry out signals, thereby increasing the flexibility of use of the integrated circuit. Improved circuitry for handling a carry in signal may also be provided in each logic module.

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John Tse