Patents by Inventor John D. Lofgren
John D. Lofgren has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8055884Abstract: One embodiment of the present invention provides a system for augmenting a pipeline with a bubble-removal circuit. During operation, the system generates a bubble-removal circuit which determines a clock-enable signal based at least on whether an upstream register has valid data and whether the pipeline is stalled. Next, the system gates the clock signal using the clock-enable signal. The augmented pipeline can determine whether a first register contains invalid data, which is associated with a bubble. Next, the augmented pipeline determines whether a second register contains valid data, wherein the second register is adjacent to and upstream from the first register. If the first register contains invalid data and the second register contains valid data, the augmented pipeline replaces the invalid data of the first register with valid data based on the valid data in the second register without propagating the invalid data to a downstream register.Type: GrantFiled: December 2, 2009Date of Patent: November 8, 2011Assignee: Synopsys, Inc.Inventors: John D. Lofgren, Brett Kobernat
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Publication number: 20100077184Abstract: One embodiment of the present invention provides a system for augmenting a pipeline with a bubble-removal circuit. During operation, the system generates a bubble-removal circuit which determines a clock-enable signal based at least on whether an upstream register has valid data and whether the pipeline is stalled. Next, the system gates the clock signal using the clock-enable signal. The augmented pipeline can determine whether a first register contains invalid data, which is associated with a bubble. Next, the augmented pipeline determines whether a second register contains valid data, wherein the second register is adjacent to and upstream from the first register. If the first register contains invalid data and the second register contains valid data, the augmented pipeline replaces the invalid data of the first register with valid data based on the valid data in the second register without propagating the invalid data to a downstream register.Type: ApplicationFiled: December 2, 2009Publication date: March 25, 2010Applicant: SYNOPSYS, INC.Inventors: John D. Lofgren, Brett Kobernat
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Patent number: 7653807Abstract: One embodiment of the present invention provides a system that removes a bubble from a pipeline. During operation, the system first detects a stall in the pipeline. The system next determines whether a first register contains invalid data, which is associated with a bubble. Next, the system determines whether a second register contains valid data, wherein the second register is adjacent to and upstream from the first register. If the first register contains invalid data and the second register contains valid data, the system replaces the invalid data of the first register with valid data based on the valid data in the second register without propagating the invalid data to a downstream register. As a result, the system removes the invalid data from the pipeline.Type: GrantFiled: September 19, 2005Date of Patent: January 26, 2010Assignee: Synopsys, Inc.Inventors: John D. Lofgren, Brett Kobernat
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Patent number: 5872793Abstract: A built-in self test architecture for testing one or more integrated circuits. Each circuit is provided with an interface compatible with IEEE standard 1149.1 and one or more scan registers containing scan cells for supplying input test data to, and receiving output test data from, the internal circuitry of the integrated circuits, a pseudo-random pattern generator for supplying patterns of test data to the boundary scan register, and a pattern compressor for compressing the output test data into a signature. The architecture also includes a single clock multiplexer, located external to the integrated circuits, for selectively supplying a system clock or a test clock to the testing components of each integrated circuit.Type: GrantFiled: August 21, 1997Date of Patent: February 16, 1999Assignee: Lockheed Martin CorporationInventors: Brett W. Attaway, John D. Lofgren, H. Ray Kelley
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Patent number: 5825922Abstract: A digital signal processing system which uses an input image including a plurality of pixels to establish boundaries of objects in the input image. Each of the pixels has a gradient value and the object includes a centroid. Using a segmentation process, the digital signal processing system decides on a perimeter surrounding the object in the input image and then repeatedly searches for a pixel having the highest gradient value and marks that pixel having the highest gradient value as an edge pixel of the object.Type: GrantFiled: August 28, 1996Date of Patent: October 20, 1998Assignee: Martin Marietta CorporationInventors: William A. Pearson, Richard W. Benton, John D. Lofgren
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Patent number: 5701308Abstract: A built-in self test architecture for testing one or more integrated circuits. Each circuit is provided with an interface compatible with IEEE standard 1149.1 and one or more scan registers containing scan cells for supplying input test data to, and receiving output test data from, the internal circuitry of the integrated circuits, a pseudo-random pattern generator for supplying patterns of test data to the boundary scan register, and a pattern compressor for compressing the output test data into a signature. The architecture also includes a single clock multiplexer, located external to the integrated circuits, for selectively supplying a system clock or a test clock to the testing components of each integrated circuit.Type: GrantFiled: October 29, 1996Date of Patent: December 23, 1997Assignee: Lockheed Martin CorporationInventors: Brett W. Attaway, John D. Lofgren, H. Ray Kelley
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Patent number: 5652912Abstract: A memory controller includes an input data path and an output data path. First circuitry generates signals to put the input data into at least one variably-dimensioned logical array of memory cells of a memory. Second circuitry generates signals to extract from the memory the contents of at least one variably-dimensioned logical array of memory cells. The memory may be double buffered such that data input to one of the portions may take place simultaneously as data output from the other of the portions. In a preferred embodiment, any combination of up to 254 total variable-dimensioned logical arrays of memory cells may be defined for input to and output from the memory. The memory controller may be viewed as supporting two simultaneous processes, an input "windowing" process for receiving windows of data and an output "windowing" process for simultaneously passing out windows of data.Type: GrantFiled: November 28, 1990Date of Patent: July 29, 1997Assignee: Martin Marietta CorporationInventors: John D. Lofgren, Richard W. Benton
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Patent number: 5604822Abstract: A digital signal processing system which uses an input image including a plurality of pixels to establish boundaries of objects in the input image. Each of the pixels has a gradient value and the object includes a centroid. Using a segmentation process, the digital signal processing system decides on a perimeter surrounding the object in the input image and then repeatedly searches for a pixel having the highest gradient value and marks that pixel having the highest gradient value as an edge pixel of the object.Type: GrantFiled: November 12, 1993Date of Patent: February 18, 1997Assignee: Martin Marietta CorporationInventors: William A. Pearson, Richard W. Benton, John D. Lofgren
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Patent number: 5600788Abstract: A testing device has an architecture including a board test interface for coupling to test points on a circuit board; a programmable processor, coupled to the board test interface, for controlling a test of the circuit board via the board test interface; and a first communications interface, coupled to the programmable processor, for coupling to a like first communications interface located on another testing device. The programmable processor uses the first communications interface for communicating test commands and test results with the other testing device, so that a complete test of a system can be produced. The testing device may further include a control port, coupled to the programmable processor, for communicating system test commands between a host processor and the programmable processor.Type: GrantFiled: January 19, 1994Date of Patent: February 4, 1997Assignee: Martin Marietta CorporationInventors: John D. Lofgren, James A. Thorne