Abstract: An integrated circuit and method utilizes a differential input receiver having a first input that receives an input signal. A reference voltage adjustment circuit produces a variable reference signal for the second input of a differential input receiver. A feedback path is provided from the output of the differential input receiver to an input of the reference voltage adjustment circuit. The reference voltage adjustment circuit dynamically varies the variable reference voltage signal to facilitate hysteresis. The variable reference voltage signal is lowered in the case of a high input signal, and raised in the case of a low input signal.

Abstract: A method and apparatus constructs a preferred certificate chain, such as a list of all certificate authorities in a shortest trusted path, based on generated certificate chain data, such as a table of trust relationships among certificate issuing units in a community of interest, to facilitate rapid validity determination of the certificate by a requesting unit. In one embodiment, requesting units, such as certificate validation units or subscribers, send queries to a common certificate chain constructing unit. Each query may identify a beginning and target certification authority in the community. The certificate chain constructing unit then automatically determines the certification chain among certification issuing units between the beginning and target certification authorities for each query and provides certificate chain data to the requesting unit. The requesting unit then performs validity determination on the certificate to be validated based on the certificate chain data.

Abstract: A buffer circuit utilizes a single gate oxide pre-buffer voltage level shifting circuit on, for example, an output buffer of an I/O pad, to accommodate different I/O pad supply voltages while maintaining normal operating voltages (degradation levels) across boundaries of single gate oxide devices that form the buffer. The single gate oxide output buffer can operate at several different supply voltages. A pre-buffer voltage level shifting circuit includes a multi-supply voltage level shifting circuit having single gate oxide devices coupled to produce a pre-buffer output signal to an output buffer. A single gate oxide cross coupled active load is coupled to the multi-supply voltage level shifting circuit and provides suitable drive voltages to at least one of cascaded buffer transistors.

Abstract: A computer network security system provides generation of a certificate revocation list (CRL) upon each revocation. The entire certificate revocation list may be published on demand, or only the portion that has changed. The computer network security system provides on-demand publishing of data identifying revoked certificates, such as revocation and expiration data, in response to receipt of revocation request data. The computer network security system stores the on-demand published data for analysis by one or more network nodes, such as a client, to determine whether a certificate is valid. The network nodes include certificate revocation list cache memory that may be selectively activated/deactivated, to effect storage/non-storage of the data identifying the revoked certificates.

Abstract: A method and apparatus for a processing system to utilize a ring buffer includes a host processor, memory, and at least one co-processor. The host processor generates a plurality of data blocks that relates to a particular application (e.g., word processing application, drafting application, presentation application, spreadsheet application, video game application, etc.). The host processor writes data elements of the data blocks into the memory, which is organized in a ring buffer manner. As the host processor enters the data elements into the ring buffer, it updates a head pointer, which indicates the most current address of a data element entered into the ring buffer, in its local cache. The co-processor retrieves the data elements from the ring buffer and performs a co-processor function in support of the particular application.

Abstract: A low common mode impedance differential driver includes an independent current source, a switching module, a dependent current source, and a bias control circuit. The independent and dependent current sources are operably coupled to the switching module to provide first and second current paths through the switching module. The bias control circuit is operably coupled to the dependent current source and to the differential output produced by the switching module. The bias control circuit provides a control signal to the dependent current source that causes the common mode of the differential output to be maintained within a desired tolerance.

Abstract: A cache memory system which minimizes the latency and latency uncertainty of data memory access by allocating spare cache memories to subsequent conflicting requests, and maintaining the prior requests in a separate table until the prior request is satisfied and the prior allocated cache is free. This reallocation of physical caches to conflicting requests is effected by maintaining an index to the physical cache that is separate and distinct from the logical index associated with the requests that cause the conflict. A conventional indexed cache mechanism is employed to derive the logical index from a subset of the address of the requested data. When the same logical index occurs from data requests from different blocks of memory, the conflict is resolved by assigning a free physical cache to the latter request. The latter assignment is stored in the indexed cache table, and the former assignment is stored in a separate table until it is no longer required.

Abstract: A certificate management system and method allows a requester, such as a subscriber using a software application, to customize certificates by selecting variable certificate content specification data. A certificate issuing unit, such as a certification authority issues a variable content based certificate in response to the requester based variable certificate content specification data, after the variable certificate content specification data has been compared with issuance criteria data to ensure that the requested certificate customization parameters do not conflict with security system constraints, such as security limits. The issuance criteria data is configurable by a security officer or other user through the certificate issuing unit. If desired, each differing software application (i.e., requester) may have its own customized certificates allowing greater flexibility for the security system and for the requesters.

Abstract: A system and method for compensating against false color from composite video source information detects when there is a diagonal luminance transition (or a cross pattern) and attenuates combed chrominance information to facilitate a reduction in a false coloring effect. A programmable threshold diagonal transition detector generates a multi-level compensation control signal, such as the amount of chrominance reduction or attenuation (in dB) to effectively notch combed chrominance data, based on a detection of a diagonal transition of luminance data among lines of video data. The multi-level compensation control signal is used by a multi-level compensator to attenuate the combed chrominance information from the 2-D adaptive comb filter.

Abstract: A method and apparatus for providing video graphics processing that includes anti-aliasing begins when a video graphics processor receives vertex parameters of an object-element and walks a first edge of the object element and a second edge of the object element. The video graphics processor walks the first and second edges based on calculations involving a decision corner and an error turn. The calculations indicate which direction to walk on a pixel by pixel basis, i.e., whether the walking should be in the major direction or the minor direction. The calculations also identify pixels that contain fragment pixel information, i.e., the pixels along the edges of the object element. For each fragment pixel, subpixel masks are created for each object element that is present in the fragmented pixel. From the subpixel masks, subpixel sequences are determined, which are used to produce pixel information of the fragment pixel.

Abstract: A method and apparatus for improved double buffering within a computing system begins when a series of data blocks are received from a central processing unit at a rate independent of a processing rate of a recipient engine. For example, a video graphics circuit receives a series of data blocks representing video frames from the central processing unit at a rate independent of the refresh rate of the display. As the data blocks are received, the video graphics circuit queues commands of the data blocks. Typically, the commands include processing commands and a processing rate synchronize command. To process the data blocks, the co-processor pulls commands from the queued list and processes them to produce recipient data. As the co-processor is producing the recipient data, it is utilizing a first buffer. The co-processor continues to process the commands and storing the results into the first buffer until the processing rate synchronize command is detected.

Abstract: A method and apparatus for anti-aliasing a rendered scene begins processing by rendering a plurality of objects of an image to a buffer to produce a rendered image. For example, the image corresponds to a particular frame of data to be displayed on a computer monitor, television, etc. Each of the objects corresponds to portions of the image and is comprised of object-elements (e.g., triangles). While the plurality of objects is being rendered, edge information of the objects that are in a most foreground position is maintained. The edge information includes a pixel offset value, which indicates the offset of an edge from a pixel center, and gradient information of the object edge. After the image has been rendered and the edge information has been collected for a particular frame of data, the rendered image is filtered based on the edge information. In particular, a two-dimensional spatial filter that derives its filtering parameters from the edge information is applied to the rendered image.

Abstract: A method and system to automatically align overlaying video data on a computer screen based on input information of R or G or B data, horizontal synchronization signal data (Hsync) and vertical synchronization signal data (Vsync) automatically reconstructs a pixel clock time base of an offboard underlying graphics source for use in aligning overlaid video using a generated vertical pixel pattern. The system and method also automatically detects a size of an active computer screen region and position of a top left hand corner and a bottom right hand corner of the active computer screen region to align overlaying video using the reconstructed pixel clock time base and a single color block pattern.

Abstract: A variable length fractional bandwidth low-pass filter is implemented as a plurality of filter stages. Each filter stage performs fractional filtering of a plurality of input samples to form an output sample. The number of filter stages is determined based on the characteristic of the filter stage, and the load is suitably balanced to allow for a minimal number of filter stages. Load balancing is applied so as to utilize each of the filter stages only when required. The load balancing is applied so as to provide a substantially equal load to each filter stage, and the number of filter stages is determined so as to allow the filter to operate substantially at the input sample rate.

Abstract: A method and apparatus for centralizing the processing of key and certificate life-cycle management is accomplished when security activation of a communication device has been detected. Security activation may occur at log-on of the secure communication device (e.g., a personal computer equipped with a security application, or applications), at activation of a security application, or at re-authentication of a security application. Once the security activation has been detected, the secured communication device accesses a depository of security information to retrieve relevant security information. The secured communication device then interprets the relevant security information to determine when local security parameters are to be changed. When local security parameters (e.g., encryption key pair, a corresponding encryption public key certificate, a signing key pair, and/or a corresponding verification public key certificate) are to be changed, the local security parameters are updated.

Abstract: An adaptive audio signal compression computer system corrects multiple input audio streams, such as digital multichannel audio streams from various audio sources, for equalization deficiencies caused primarily by attenuation factors experienced by a listener's human ear. A compression stage (filter stage) adaptively compresses (filters) an input audio stream by selecting the ear response data that includes a plurality of selectable sets of filter coefficients wherein each set of filter coefficients corresponds to an inverse audible listening response curve for a predetermined audio volume level. When available from an audio source, the system provides audio source type data to an adaptive compression stage and also generates a compression control signal in response to the source type data to control the compression.

Abstract: An image reconstruction system adaptively de-interlaces video stream content using image data comparison techniques when the interlaced input video stream does not contain pre-coded non-interlaced to interlaced conversion status data. In one embodiment, the system uses a signature generator which generates a plurality of field signature values on a per field basis by determining region values based on fluctuations in pixel data, such as luminance data within a horizontal scan line to detect changes in motion. The field signature values are then analyzed to determine a probability that the content is one of several types such as content that has undergone non-interlaced to interlaced conversion, such as pull down conversion for film captured content. Also, independent of whether conversion has occurred, the system analyzes the video streams to determine whether the video stream contains a paused image or slow motion playback of images and de-interlaces accordingly.

Abstract: A method of generating a substitution box (S-box) involves generating an S-box with desired characteristics, forming a new S-box with another column such that the new S-box has the desired characteristics as well, and continuing to add columns in these ways until the S-box has the proper size.

Abstract: A horizontal phase detection circuit and system detects the phase of the horizontal synchronization pulse for a horizontal synchronization phase lock loop using positive and negative fractional error compensation. The positive and negative fractional errors are determined to get a more accurate detection of where a horizontal synchronization pulse crosses a synchronization signal slice level. Using both positive and negative fractional compensation, the circuit and method detects the horizontal synchronization pulse width and center of the pulse. In addition, if desired, an adaptive slice level generator generates a variable slice level threshold based on a signal strength of the input video signal to facilitate improved detection in the cases where the video information is weak even after gain control has been applied.

Abstract: An audio bus interface system and method interfaces a plurality of digital signal processing devices to an audio bus to facilitate variable processing loading on the DSPs. The audio bus contains frames with synchronization data. The system utilizes a programmable interrupt controller for each digital signal processing unit. The programmable interrupt controller controls the rate at which a given DSP can be interrupted. The respective digital signal processor controls the programmable interrupt controller to maximize its throughput. Also, an audio format translator allows differing audio format protocols to be processed by the same audio DSP.