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About 2,304 papers for “Prefix code”

Fast prefix code processing

Renato Pajarola · 2004

As large main memory becomes more and more available at reasonable prices, processing speed of large data sets becomes more important than reducing main memory usage of internal data structures which are small compared to the available main memory capacity. In this paper we describe the use of a finite state machine for fast processing of prefix codes that significantly improves decoding performance in practice, and that is easy to implement. We present an intuitive explanation of this method, an extension to discover symbol boundaries in compressed data, implementation details, and we also provide experimental performance results.

Cited by 7

The Characterization of Maximal Prefix Code

Bo Xu · 2007

Let X* be the free monoid on the alphabet set X.The concept of a transversal of the language diagram Γ(X*) is introduced by constructing a language diagram Γ(X*) with X* as the node set and a characterization of prefix code is given.In addition,we proved that a maximal prefix code with finite length that contains the alphabet in X must be a maximal code.

Cited by 0

Bidirectionally decodable streams of prefix code-words

Bernd Girod · IEEE Communications Letters · 1999

A new general scheme is introduced that allows bidirectional decoding of variable length coded bitstreams from either end. Except for a small fixed number of extra bits appended to a sequence of code words, the scheme is as efficient as Huffman coding. The extra operations required at the coder and decoder are code word reversal and one EXOR for each bit.

Cited by 33

On the Maximum Size of a Prefix Code

Peter Horák, Viliam Hromada, Otokar Grošek · 2022

<div>In this paper, we investigate the maximum size of a minimal dictionary of a binary prefix-code string. We develop exact formulas for the maximum number of codewords of a minimal dictionary, which belongs to a binary string of some length. Further, we elaborate on the computational complexity of our approach and its relation to the Lambert function. We also present a way, how this information enables us to efficiently construct a Huffman code in the case of uniform probability distribution of codewords.</div><div><br></div><div>The paper is of mathematical nature, i.e. all the methodology used in the paper is based on mathematical proofs.<br></div>

Cited by 1Open access

On the Maximum Size of a Prefix Code

Peter Horák, Viliam Hromada, Otokar Grošek · 2022

<div>In this paper, we investigate the maximum size of a minimal dictionary of a binary prefix-code string. We develop exact formulas for the maximum number of codewords of a minimal dictionary, which belongs to a binary string of some length. Further, we elaborate on the computational complexity of our approach and its relation to the Lambert function. We also present a way, how this information enables us to efficiently construct a Huffman code in the case of uniform probability distribution of codewords.</div><div><br></div><div>The paper is of mathematical nature, i.e. all the methodology used in the paper is based on mathematical proofs.<br></div>

Cited by 0Open access

On Some Properties of Graph of Prefix Code

Nikolai Krainiukov, Mikhail Abramyan, Boris Melnikov · Journal of Applied Mathematics and Physics · 2024

We investigate decomposition of codes and finite languages. A prime decomposition is a decomposition of a code or languages into a concatenation of nontrivial prime codes or languages. A code is prime if it cannot be decomposed into at least two nontrivial codes as the same for the languages. In the paper, a linear time algorithm is designed, which finds the prime decomposition. If codes or finite languages are presented as given by its minimal deterministic automaton, then from the point of view of abstract algebra and graph theory, this automaton has special properties. The study was conducted using system for computational Discrete Algebra GAP.

Cited by 0Open access

Test Data Compression Using Variable Prefix Run Length (VPRL) Code

Krishna Kumar, Karen Thangam Jacob, B. Manjurathi · IOSR Journal of VLSI and Signal processing · 2014

One of the major challenges in testing a system-on-a-chip (SoC) is dealing with the large test data volume and large scan power consumption. To reduce the volume of test data, several test data compression techniques have been proposed. This paper presents a new test data compression scheme, which reduces test data volume for a system-on-a-chip (SoC). The proposed approach is based on the use of MT (Minimum Transition)-fill technique and Variable Prefix Run Length (VPRL) codes for test data compression. These VPRL codes can efficiently compress the data streams, that are composed of both runs of 0s and 1s. Experimental results for ISCAS'89 benchmark circuits supports and proves the proposed approach, better to the other existing techniques, by reducing test data volume.

Cited by 0Open access

APT: Adaptive Prefix-Tuning on Pretrained Models for Code Intelligence

Yue Wu, Yaoxiang Yu, Zhengming Yuan et al. · 2024

In the field of code intelligence, pretrained models exhibit impressive performance. However, it is imperative to modify all model parameters and maintain full copies for various tasks. Moreover, the effectiveness of fine-tuning a pretrained model depends on the availability of data, which can be constrained in practical settings. Prefix-tuning, a novel approach in NLP for addressing the aforementioned issue, has demonstrated promising results in numerous tasks. This paper aims to investigate the potential of prefix-tuning in the field of code intelligence, an area that has been relatively understudied. We also acknowledge the critical role of initialization in the performance of prefixtuning, which has been neglected in prior research. To address this gap, we introduce a novel method termed "adaptive prefixtuning". This approach entails training the prefix parameters on adapting tasks, followed by subsequent tuning on downstream tasks. We perform prefix-tuning and adaptive prefix-tuning using well-known pretrained models, CodeT5 and CodeGPT, and conduct experiments on four code intelligence tasks, namely, defect detection, code completion, code summarization, and code translation. Our experiments revealed that, in situations with restricted data availability, adaptive prefix-tuning yields substantial performance enhancements compared to fine-tuning, whereas prefix-tuning does not exhibit evident advantages. Furthermore, adaptive prefix-tuning has demonstrated superior performance relative to prefix-tuning in scenarios with comprehensive datasets. In certain cases, it has even outperformed traditional fine-tuning methods. Our findings indicate that within the field of code intelligence, adaptive prefix-tuning can serve as an effective substitute for fine-tuning, especially in situations with constrained data availability.

Cited by 2

Code-assisted SC/FDE block transmission with reduced cyclic prefix overhead

Gusmão, António, Torres, Paulo, Dinis, Rui et al. · Repositório Científico do Instituto Politécnico de Castelo Branco (Instituto Politécnico de Castelo Branco) · 2005

For conventional CP-assisted (Cyclic Prefix) SC/FDE implementations (Single- Carrier/Frequency Domain Equalisation), as well as for OFDM implementations (Orthogonal Frequency Division Multiplexing), the CP length is known to be selected on the basis of the expected maximum delay spread. Next, the data block size can be chosen to be large enough to minimise the CP overhead, yet small enough to make the channel variation over the block negligible. This paper considers the possibility of reducing the overall CP assistance, when transmitting sequences of SC blocks, while avoiding an excessively long FFT block for FDE purposes and keeping good performances through a moderate increase of the FDE receiver complexity. Firstly, we present an algorithm for a Decision-Directed Correction (DDC) of the FDE inputs when the CP is not long enough to cope with the time-dispersive channel effects. Next, we present and evaluate a novel class of reduced CP SC/FDE schemes, which takes advantage of the DDC algorithm for replacing ”useless” CP redundancy by fully useful channel coding redundancy. A very efficient block transmission, especially for both strongly time-dispersive and time-varying channel conditions, is then achieved.

Cited by 0

Place Dependency of a Petri Net Generating a Maximal Prefix Code *

Yoshiyuki Kunimochi · 2016

Abstract In this paper we deal with prefix codes, called CPN languages, defined on Petri nets. And the family CPN of all CPN languages is included in the family of all context-sensitive languages. The subclass $mCPN $ and NmCPN of CPN are a family of prefix codes which are maximal prefix codes and a family of prefix codes defined on input-ordinal Petri nets. NmCPN is obviously included in $mCPN $. But its converse inclusion is still a opcn problem. We have already proved under some restricted $Pe $ tri nets, for example, Petri iiets have at most two places or at most one transition. We coiisider this pioblein in thc case that Pctri nets have more than two places. 1

Cited by 0

Designing prefix code to save energy for wirelessly powered wireless sensor networks

Yi‐hua Zhu, Ertao Li, Kaikai Chi et al. · IET Communications · 2018

In the Internet of Things, wireless sensor networks (WSNs) are widely deployed. In recent years, wirelessly powered WSNs or battery‐free WSNs (BF‐WSNs), in which the nodes harvest energy from radio signals in the environment, have been emerging to support sustainable operation for WSNs. It is significant to design an energy‐efficient data delivery scheme for the BF‐WSNs. In this study, the authors propose the prefix code based scheme (PCBS) to save energy in data delivery by making use of the energy consumption disparity (ECD) between transmitting/receiving bit 0 and bit 1 in the existing non‐modulation baseband transmission or carrier‐modulation based passband transmission. The authors formulate an optimisation problem and use genetic algorithm to find its solution so that the energy‐efficient prefix codebook is obtained. The codebook dilutes the ECD by containing the energy‐consuming bit as few as possible, and the PCBS maps each m ‐bit data block into a prefix codeword in the codebook to conduct energy‐efficient transmission at the transmitter and vice versa at the receiver. Both the experiments on wireless identification sensing platform and the simulations demonstrate that the proposed PCBS outperforms the existing schemes in terms of energy saving.

Cited by 7Open access

The syntactic monoid of the semigroup generated by a maximal prefix code

Mario Petrich, C. M. Reis, G. Thierrin · Proceedings of the American Mathematical Society · 1996

In this paper we investigate the semigroup structure of the syntactic monoid $\mathrm {Syn}(C^+)$ of $C^+$, the semigroup generated by a maximal prefix code $C$ for which $C^+$ is a single class of the syntactic congruence. In particular we prove that for such a prefix code $C$, either $\mathrm {Syn}(C^+)$ is a group or it is isomorphic to a special type of submonoid of $G\times \mathcal {T}(R)$ where $G$ is a group and $\mathcal {T}(R)$ is the full transformation semigroup on a set $R$ with more than one element. From this description we conclude that $\mathrm {Syn}(C^+)$ has a kernel $J$ which is a right group. We further investigate separately the case when $J$ is a right zero semigroup and the case when $J$ is a group.

Cited by 3Open access