摘要:
A magnetoresistive solid-state storage device (MRAM) employs error correction coding (ECC) to form ECC encoded stored data. In a read operation, a set of test cells in a test row are used to predict failures amongst a set of cells of interest storing a block of ECC encoded data. Erasure information is formed from these predictions which identifies potentially unreliable symbols in the block of ECC encoded data, and the ability of a decoder to perform ECC decoding is substantially enhanced.
摘要:
In various embodiments of the present invention, optimal or near-optimal multidirectional context sets for a particular data-and/or-signal analysis or processing task are determined by selecting a maximum context size, generating a set of leaf nodes corresponding to those maximally sized contexts that occur in the data or signal to be processed or analyzed, and then building up and concurrently pruning, level by level, a multidirectional optimal context tree constructing one of potentially many optimal or near-optimal context trees in which leaf nodes represent the context of a near-optimal or optimal context set that may contain contexts of different sizes and geometries. Pruning is carried out using a problem-domain-related weighting function applicable to nodes and subtrees within the context tree. In one described embodiment, a bi-directional context tree suitable for a signal denoising application is constructed using, as the weighting function, an estimated loss function.
摘要:
Various embodiments of the present invention are directed to analysis of biopolymer sequences by introducing artificial noise into the sequences and then applying a denoiser to remove the artificial noise, monitoring the denoisability of each portion of the sequence by comparing the product of the denoiser and the original sequence. Portions of biopolymer sequences involved in certain cellular functions, such as genes within DNA sequences, often encode information in codes that are highly resilient to discrete, local corruption, such as DNA sequence mutations. Portions of DNA involved in other types of cellular functions may be less resilient to random errors, or, in other cases, may be so uniformly repetitive in sequence that random errors can be extremely easily identified and corrected. The denoisability of portions of biopolymer sequences into which random errors are introduced may thus rather directly reflect the error tolerance and error recognizability within the portions of biopolymer sequences. Rapid changes in denoisability in a continuous computation of denoisability along a biopolymer sequence may, in turn, indicate boundaries between portions of the biopolymer sequence having different biological functions. Thus, a denoiser may be a computationally efficient tool for analyzing biopolymer sequences in order to differentiate different portions of the biopolymer sequences having different biological functions.
摘要:
Use of Generalized Context Trees, a means for assigning a unique state from a finite set to any string, is provided. The method optionally refines the generalized context tree into a refined generalized context tree having a finite state machine (FSM) property. Refining occurs whenever the generalized context tree does not have the finite state machine property. Alternately, a method for constructing a representation of a source usable within an FSM is provided, comprising evaluating a node comprising a suffix tail and verifying the suffix tail is included in the representation, and inserting at least one node to the representation when the suffix tail is not in the representation.
摘要:
An apparatus and method for processing a received signal that has been corrupted by a channel to generate a processed signal having less signal corruption than the received signal is disclosed. The apparatus stores the received signal, information specifying the probability that a symbol having a value I will be converted to a symbol having a value J by the channel, and information specifying a signal degradation function that measures the signal degradation that occurs if a symbol having the value I is replaced by symbol having a value J. The controller replaces each symbol having a value I in a context of that symbol in the received signal with a symbol having a value J that minimizes the overall signal degradation in the processed signal relative to the underlying noise-free signal as estimated via the observed statistics within that context.
摘要:
An apparatus and method are shown for multiplying vectors of length n in a finite field. A first vector is circularly shifted in a first shift register under control of a shift signal. A second vector is circularly shifted in a second shift register also under control of the shift signal. An accumulated result vector is circularly shifted in a third shift register under control of the shift signal. Elements of the second vector are logically combined according to a tensor of the multiplication operation to obtain an intermediate result which is combined with the elements of the accumulated result vector to obtain a combination result vector. However, the combination result vector is only loaded into the third shift register when a logic ‘1’ value is present in a first position of the first shift register. Therefore, the first, second and third shift registers can be circularly shifted until a logic ‘1’ is encountered in the first vector, at which time the combination result vector is loaded into the third shift register. Since a vector will, on average, contain n/2 elements that are logic ‘1’, the number of operations for a multiplication can be reduced, on average, to n/2.
摘要:
A lossless image compression encoder/decoder system having a context determination circuit and a code generator. The image compressor uses the context of a pixel to be encoded to predict the value of the pixel and determines a prediction error and maps the prediction error to a mapped value having a distribution suitable for Golomb encoding. The image compressor contains a context quantizer that quantizes the context of pixels. The image compressor determines a Golomb parameter based on the context and historical information gathered during the coding of an image. To avoid systematic prediction biases in an image, the image compressor adjusts the distribution of prediction residuals to a distribution suitable for Golomb coding. As it encodes a particular pixel, the encoder uses the Golomb parameter to determine a Golomb code for the prediction error and encodes that value. To decompress an image, the decompressor determines and quantizes the context of each pixel being decoded. The decompressor uses the same pixels as the compressor to determine the context. The decompressor uses the context and historical information gathered during the decompression of the image to determine a Golomb parameter for the context in which the pixel occured. The decompressor retrieves from the compressed image the code for the pixel. Using the Golomb parameter and the retrieved code, the decompressor determines the mapped value of the code. The decompressor then uses the inverse mapping to determine the error value. The decompressor uses a predictor to predict the value of the pixel based on the context and adds the error value to determine the actual value of the pixel. In one embodiment the image compressor uses an alphabet extension, embedded in its context model, in specific low gradient contexts to reduce the redundancy of the encoding. Other systems and methods are disclosed.
摘要:
A class of lossless data compression algorithms use a memory-based dictionary of finite size to facilitate the compression and decompression of data. To reduce the loss in data compression caused by dictionary resets, a standby dictionary is used to store a subset of encoded data entries previously stored in a current dictionary. In a second aspect of the invention, data is compressed/decompressed according to the address location of data entries contained within a dictionary built in a content addressable memory (CAM). In a third aspect of the invention, the minimum memory/high compression capacity of the standby dictionary scheme is combined with the fast single-cycle per character encoding/decoding capacity of the CAM circuit. In a fourth aspect of the invention, a selective overwrite dictionary swapping technique is used to allow all data entries to be used at all times for encoding character strings.
摘要:
The invention is a dictionary initialization scheme adaptive to changes in the type and structure of input data. The compression ratio is increased by minimizing the number of data entries used to represent single characters in the input data. By using fewer codes than what is normally used to represent characters in an array of input data, the dictionary can have fewer entries than the alphabet size. A further aspect of the invention implements a type of run-length encoding in the LZ methodology which exploits the redundant structure existing in the compressed stream in the presence of a long run. Some of the codewords in the compressed stream are deleted but can be recovered at the decompression site. The foregoing LZE method is used alone, or used in combination with other methods to form a compression scheme that is especially useful for transmitting network packets.
摘要:
A multi-state memory system with encoding that minimizes half-select currents. The system includes an array of row and column conductors with a plurality of storage cells each capable of being placed into any of three or more physical states. An encoder is connected to receive data bits for storage and to apply activation signals to the row and column conductors to write information to the storage cells. The encoder is programmed to encode the data bits into entries in an array having one row corresponding with each row conductor and one column corresponding with each column conductor; select entries in the array according to half-select currents of the storage cells; apply a predetermined one-dimensional mapping that increases the value of at most one entry in the array to obtain a mapped array; and write entries of the mapped array into the storage cells.