13469693
Validating Word-Oriented Processors for Bit and Multi-word Operations
We examine secure computing paradigms to identify any new architectural challenges for future general-purpose processors. Some essential security functions can be provided by different classes of cryptography algorithms. We identify two categories of operations in these algorithms that are not common in previous general-purpose workloads: bit operations within a word and multi-word operations. Both challenge the basic word orientation of processors. We show how very complex bit-level operations, namely arbitrary bit permutations within a word, can be achieved in O(1) cycles, rather than O(n) cycles as in existing RISC processors. We describe two solutions: one using only microarchitecture changes, and another with Instruction Set Architecture (ISA) support. We generalize our solutions to define datarich execution with MOMR (Multi-word Operands Multi-word Result) functional units. This can address both challenges, leveraging available resources in typical processors with minimal additional cost. Thus we validate the basic word-orientation of processor architectures, since they can also provide superior performance for both bit and multi-word operations needed by cryptographic processing.
621158
Arbitrary bit permutations in one or two cycles
Symmetric-key block ciphers encrypt data, providing data confidentiality over the public Internet. For interoperability reasons, it is desirable to support a variety of symmetric-key ciphers efficiently. We show the basic operations performed by a variety of symmetric-key cryptography algorithms. Of these basic operations, only bit permutation is very slow using existing processors, followed by integer multiplication. New instructions have been proposed recently to accelerate bit permutations in general-purpose processors, reducing the instructions needed to achieve an arbitrary n-bit permutation from O(n) to O(log(n)). However, the serial data-dependency between these log(n) permutation instructions prevents them from being executed in fewer than log(n) cycles, even on superscalar processors. Since application specific instruction processors (ASIPs) have fewer constraints on maintaining standard processor datapath and control conventions, can we achieve even faster permutations? We propose six alternative ASIP approaches to achieve arbitrary 64 bit permutations in one or two cycles, using new BFLY and IBFLY instructions. This reduction to one or two cycles is achieved without increasing the cycle time. We compare the latencies of different permutation units in a technology independent way to estimate cycle time impact. We also compare the alternative ASIP architectures and their efficiency in performing arbitrary 64 bit permutations.
8693957
Single-Cycle Bit Permutations with MOMR Execution
Secure computing paradigms impose new architectural challenges for general-purpose processors. Cryptographic processing is needed for secure communications, storage, and computations. We identify two categories of operations in symmetric-key and public-key cryptographic algorithms that are not common in previous general-purpose workloads: advanced bit operations within a word and multi-word operations. We define MOMR (Multiple Operands Multiple Results) execution or datarich execution as a unified solution to both challenges. It allows arbitrary n-bit permutations to be achieved in one or two cycles, rather than O(n) cycles as in existing RISC processors. It also enables significant acceleration of multi-word multiplications needed by public-key ciphers. We propose two implementations of MOMR: one employs only hardware changes while the other uses Instruction Set Architecture (ISA) support. We show that MOMR execution leverages available resources in typical multi-issue processors with minimal additional cost. Multi-issue processors enhanced with MOMR units provide additional speedup over standard multi-issue processors with the same datapath. MOMR is a general architectural solution for word-oriented processor architectures to incorporate datarich operations.
5848156
Swarm Intelligence Clustering Algorithm Based on Attractor
Ant colonies behavior and their self-organizing capabilities have been popularly studied, and various swarm intelligence models and clustering algorithms also have been proposed. Unfortunately, the cluster number is often too high and convergence is also slow. We put forward a novel structure-attractor, which actively attracts and guides the ant's behavior, and implement an efficient strategy to adaptively control the clustering behavior. Our experiments show that swarm intelligence clustering algorithm based on attractor (SICABA for short) greatly improves the convergence speed and clustering quality compared with LF and also has many notable virtues such as flexibility, decentralization compared with conventional algorithms.
18028792
Semantics Supervised Cluster-Based Index for Video Databases
High-dimensional index is one of the most challenging tasks for content-based video retrieval (CBVR). Typically, in video database, there exist two kinds of clues for query: visual features and semantic classes. In this paper, we modeled the relationship between semantic classes and visual feature distributions of data set with the Gaussian mixture model (GMM), and proposed a semantics supervised cluster based index approach (briefly as SSCI) to integrate the advantages of both semantic classes and visual features. The entire data set is divided hierarchically by a modified clustering technique into many clusters until the objects within a cluster are not only close in the visual feature space but also within the same semantic class, and then an index entry including semantic clue and visual feature clue is built for each cluster. Especially, the visual feature vectors in a cluster are organized adjacently in disk. So the SSCI-based nearest-neighbor (NN) search can be divided into two phases: the first phase computes the distances between the query example and each cluster index and returns the clusters with the smallest distance, here namely candidate clusters; then the second phase retrieves the original feature vectors within the candidate clusters to gain the approximate nearest neighbors. Our experiments showed that for approximate searching the SSCI-based approach was faster than VA+-based approach; moreover, the quality of the result set was better than that of the sequential search in terms of semantics.
19898332
An algorithm for partial Grundy number on trees
A coloring of a graph G=(V,E) is a partition {V"1,V"2,...,V"k} of V into independent sets or color classes. A vertex [email protected]?V"i is a Grundy vertex if it is adjacent to at least one vertex in each color class V"j for every j
18050486
Perspectives on cognitive informatics
From a scientific perspective explaining how the brain thinks is a big goal. Cognitive informatics studies intelligent behavior from a computational point of view in terms of updated research efforts and processes of brain science and neuroscience. Cognitive informatics is the interdisciplinary study of cognition. Cognition includes mental states and processes, such as thinking, reasoning, remembering, language understanding and generation, visual and auditory perception, learning, consciousness, emotions, etc. In this paper we will point out basic research topics of learning, memory, thought, language, and neural computing which are active fields related to cognitive informatics.