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In many digital systems, various sequential blocks are used. This paper is devoted to the case where the model of a Mealy finite state machine (FSM) represents the behaviour of a sequential block. The chip area occupied by an FSM circuit is one of the most important characteristics used in logic synthesis. In this paper, a method is proposed which aims at reducing LUT counts for FPGA-based Mealy FSMs with transformation of state codes into FSM outputs. This is done using the combined state codes. Such an approach allows excluding a block of transformation of binary state codes into extended state codes. The proposed method leads to LUT-based Mealy FSM circuits having exactly three levels of logic blocks. Under certain conditions, each function for any logic level is represented by a circuit including a single LUT. The proposed approach is illustrated with an example of synthesis. The results of experiments conducted using standard benchmarks show that the proposed method produces LUT-based FSM circuits with significantly smaller LUT counts than is the case for circuits produced by other investigated methods (Auto and One-hot of Vivado, JEDI, and transformation of binary codes into extended state codes). The LUT count is decreased by an average of 17.96 to 91.8%. Moreover, if some conditions are met, the decrease in the LUT count is accompanied with a slight improvement in the operating frequency compared with circuits based on extended state codes. The advantages of the proposed method multiply with increasing the numbers of FSM inputs and states.

A method is proposed which aims at reducing the number of LUTs in the circuits of FPGA-based Mealy finite state machines (FSMs) with transformation of collections of outputs into state codes. The reduction is achieved due to the use of two-component state codes. Such an approach allows reducing the number of state variables compared with FSMs based on extended codes. There are exactly three levels of LUTs in the resulting FSM circuit. Each partial function is represented by a single-LUT circuit. The proposed method is illustrated with an example of synthesis. The experiments were conducted using standard benchmarks. They show that the proposed method produces FSM circuits with significantly smaller LUT counts compared with those produced by other investigated methods (Auto and One-hot of Vivado, JEDI, and transformation of output collection codes into extended state codes). The LUT count is decreased by, on average, from 9.86% to 59.64%. The improvement of the LUT count is accompanied by a slightly improved performance. The maximum operating frequency is increased, on average, from 2.74% to 12.93%. The advantages of the proposed method become more pronounced with increasing values of FSM inputs and state variables.

Replacement policies have an important role in the functioning of the cache memory of processor cores. The implementation of a successful policy allows us to increase the performance of the processor core and the computer system as a whole. Replacement policies are most often evaluated by the percentage of cache hits during the cycles of the processor bus when accessing the cache memory. The policies that focus on replacing the Least Recently Used (LRU) or Least Frequently Used (LFU) elements, whether instructions or data, are relevant for use. It should be noted that in the paging cache buffer, the above replacement policies can also be used to replace address information. The pseudo LRU (PLRU) policy introduces replacing based on approximate information about the age of the elements in the cache memory. The hardware implementation of any replacement policy algorithm is the circuit. This hardware part of the processor core has certain characteristics: the latency of the search process for a candidate element for replacement, the gate complexity, and the reliability. The characteristics of the PLRUt and PLRUm replacement policies are synthesized and investigated. Both are the varieties of the PLRU replacement policy, which is close to the LRU policy in terms of the percentage of cache hits. In the current study, the hardware implementation of these policies is evaluated, and the possibility of adaptation to each of the policies in the processor core according to a selected priority characteristic is analyzed. The dependency of the rise in the delay and gate complexity in the case of an increase in the associativity of the cache memory is shown. The advantage of the hardware implementation of the PLRUt algorithm in comparison with the PLRUm algorithm for higher values of associativity is shown. [ABSTRACT FROM AUTHOR]

Methods for reducing power consumption in circuits of finite state machines (FSMs) are discussed in this review. The review outlines the main approaches to solving this problem that have been developed over the last 40 years. The main sources of power dissipation in CMOS circuits are shown; the static and dynamic components of this phenomenon are analyzed. The power consumption saving can be achieved by using coarse-grained methods common to all digital systems. These methods are based on voltage or/and clock frequency scaling. The review shows the main structural diagrams generated by the use of these methods when optimizing the power characteristics of FSM circuits. Also, there are various known fine-grained methods taking into account the specifics of both FSMs and logic elements used. Three groups of the fine-grained methods targeting FPGA-based FSM circuits are analyzed. These groups include clock gating, state assignment, and replacing look-up table (LUT) elements by embedded memory blocks (EMBs). The clock gating involves a separate or joint use of such approaches as the (1) decomposition of FSM inputs and (2) disabling FSM inputs. The aim of the power-saving state assignment is to reduce the switching activity of a resulting FSM circuit. The replacement of LUTs by EMBs allows a reduction in the power consumption due to a decrease in the number of FSM circuit elements and their interconnections. We hope that the review will help experts to use known methods and develop new ones for reducing power consumption. We think that a good knowledge and understanding of existing methods of reducing power consumption is a prerequisite for the development of new, more effective methods to solve this very important problem. Although the methods considered are mainly aimed at FPGA-based FSMs, they can be modified, if necessary, and used for the power consumption optimization of FSM circuits implemented with other logic elements. [ABSTRACT FROM AUTHOR]

Practically, any digital system includes sequential blocks represented using a model of finite state machine (FSM). It is very important to improve such FSM characteristics as the number of logic elements used, operating frequency and consumed energy. The paper proposes a novel technology-dependent design method targeting a decrease in the number of look-up table (LUT) elements and their levels in logic circuits of FPGA-based Mealy FSMs. It produces FSM circuits having three levels of logic blocks. Also, it produces circuits with regular systems of interconnections between the levels of logic. The method is based on dividing the set of internal states into two subsets. Each subset corresponds to a unique part of an FSM circuit. Only a single LUT is required for implementing each function generated by the first part of the circuit. The second part is represented by a multi-level circuit. The proposed method belongs to the group of two-fold state assignment methods. Each internal state is encoded as an element of the set of states and as an element of some of its subsets. A binary state assignment is used for states corresponding to the first part of the FSM circuit. The one-hot assignment is used for states corresponding to the second part. An example of FSM synthesis with the proposed method is shown. The experiments with standard benchmarks are conducted to analyze the efficiency of the proposed method. The results of experiments show that the proposed approach leads to diminishing the number of LUTs in the circuits of rather complex Mealy FSMs having more than 15 internal states. The positive property of this method is a reduction in energy consumption (without any overhead cost) and an increase in operating frequency compared with other investigated methods.

A method is proposed targeting a decrease in the number of LUTs in circuits of FPGA-based Mealy FSMs. The method improves hardware consumption for Mealy FSMs with the encoding of collections of output variables. The approach is based on constructing a partition for the set of internal states. Each state has two codes. It diminishes the number of arguments in input memory functions. An example of synthesis is given, along with results of investigations. The method targets rather complex FSMs, having more than 15 states.

This work proposes a method for hardware reduction in circuits of Mealy finite state machines (FSMs). The circuits are implemented as networks of interconnected look-up table (LUT) elements. The FSMs with twofold state assignment and encoding of output collections are discussed. The method is based on using two LUT-based cores to implement systems of partial Boolean functions. One of the cores uses only maximum binary codes, while the second core is based on the use of extended state codes. The hardware reduction is based on diminishing the number of transformed maximum binary codes. This leads to FPGA-based FSM circuits with three levels of logic blocks. Each logic block has a single level of LUTs. As a result, partial functions are represented by single-LUT circuits. The article shows a step-by-step procedure for the transition from the initial form of the FSM representation to its logical circuit (a network of programmable look-up table elements, flip-flops, and interconnects). The results of experiments conducted with standard benchmarks show that the proposed approach produces LUT-based FSM circuits with significantly better area characteristics than for circuits produced by such methods as Auto and One-Hot of Vivado, JEDI, and twofold state assignment. Compared to these methods, the number of LUTs is reduced from 9.44% to 69.98%. Additionally, the proposed method leads to the following phenomenon: the maximum operating frequency is slightly improved as compared with FSM circuits based on twofold state assignment (up to 0.6%). The negative effect of these improvements is an increase in power consumption. However, it is extremely insignificant (up to 1.56%). As the values of the FSM's main characteristics grow, there is an increase in the gain from the application of the proposed method. The conditions for applying the proposed method are determined. A generalized architecture consisting of three blocks of partial functions and a method for synthesizing an FSM with this architecture are proposed. A method for selecting one of the seven architectures generated by the generalized architecture is proposed. [ABSTRACT FROM AUTHOR]

This study focuses on creating and investigating models that optimize load balancing in communication networks by managing routing and traffic limitations. The purpose is to use these models to optimize the network's routing and traffic limitations while ensuring predictable quality of service levels, and adhering to traffic engineering requirements for routing and limiting traffic at the network edge. In order to achieve this aim, a mathematical optimization model was developed based on a chosen optimality criterion. Two modifications of the traffic engineering routing were created, including the linear limitation model (TER-LLM) and traffic engineering limitation (TER-TEL), each considering the main features of packet flow: intensity and priority. The proposed solutions were compared by analyzing various data inputs, including the ratio of flow parameters and the intensity with which packets will be limited at the border router. The study presents recommendations on the optimal use of the proposed solutions based on their respective features and advantages. [ABSTRACT FROM AUTHOR]

The main purpose of the method proposed in this article is to reduce the number of look-up-table (LUT) elements in logic circuits of sequential devices. The devices are represented by models of Mealy finite state machines (FSMs). Thesee are so-called MPY FSMs based on two methods of structural decomposition (the replacement of inputs and encoding of output collections). The main idea is to use two types of state codes for implementing systems of partial Boolean functions. Some functions are based on maximum binary codes; other functions depend on extended state codes. The reduction in LUT counts is based on using the method of twofold state assignment. The proposed method makes it possible to obtain FPGA-based FSM circuits with four logic levels. Only one LUT is required to implement the circuit corresponding to any partial function. An example of FSM synthesis using the proposed method is shown. The results of the conducted experiments show that the proposed approach produces LUT-based FSM circuits with better area-temporal characteristics than for circuits produced using such methods as Auto and One-hot of Vivado, JEDI, and MPY FSMs. Compared to MPY FSMs, the values of LUT counts are improved. On average, this improvement is 8.98%, but the gain reaches 13.65% for fairly complex FSMs. The maximum operating frequency is slightly improved as compared with the circuits of MPY FSMs (up to 0.64%). For both LUT counts and frequency, the gain increases together with the growth for the numbers of FSM inputs, outputs and states. [ABSTRACT FROM AUTHOR]

This work is devoted to improving a two-level hierarchical queue management method based on priority and balancing under the interaction prediction principle. The lower level of calculations was connected with the problem optimization solution and was responsible for two tasks. Firstly, the packet flow aggregation and distribution among the macro-queues and sub-queues organized on the router interface must solve the congestion management problem. Secondly, the resource allocation problem solution was related to the balanced allocation of interface bandwidth among the sub-queues, which were weighted relative to their priorities under the traffic-engineering queues. The method's lower-level functions were recommended to be placed on a set of processors of a routing device responsible for servicing the packets of individual macro-queues. At the same time, the processor coordinator could perform the functions of the upper-level calculations, providing interface bandwidth allocation among the macro-queues. The numerical research results of the proposed two-level hierarchical queue management method confirmed its effectiveness in ensuring high scalability. Balanced, priority-based packet flow distribution and interface bandwidth allocation among the macro-queues and sub-queues were implemented. In addition, the time was reduced for solving tasks related to queue management. The method demonstrated high convergence of the coordination procedure and the quality of the centralized calculations. The proposed approach can be used in various embedded systems. [ABSTRACT FROM AUTHOR]

A method is proposed that is focused on reducing the chip area occupied by logic elements creating the circuit of Mealy finite state machines (FSMs). The proposed method is aimed at FSM circuits implemented with internal resources of field-programmable gate arrays (FPGA). The required chip area is estimated by the number of look-up table (LUT) elements in a particular circuit. The method is based on mutual application of two methods of structural decomposition. The first of them is based on dividing the set of outputs and using unitary-maximum encoding of collections of FSM outputs. The second method is based on dividing the set of states by classes of compatible states. The optimization is achieved by replacing the maximum binary state codes by two-part codes proposed in this article. Each two-part state code consists of a code of a class including a particular state and a maximum binary code of this state inside a particular class. The proposed approach leads to three-level LUT-based Mealy FSM circuits. The first logic level generates three types of partial functions: unitary encoded outputs, variables encoding collections of outputs, and input memory functions. Each partial function is represented by a circuit including a single LUT. The LUTs from the second logic level generate final values of these functions. The LUTs from the third level implement outputs using collections of outputs. An example of synthesis applying the proposed method is discussed. The experiments were conducted using standard benchmark FSMs. Their results showed significant improving of the area occupied by an FSM circuit. The LUT count decreased on average by 9.49%. The positive side effect of the proposed method was increasing the value of the maximum operating frequency (on average, by 8.73%). The proposed method is advisable to use if a single-level LUT-based implementation of the FSM circuit is impossible. [ABSTRACT FROM AUTHOR]

A method is proposed which aims at reducing the numbers of look-up table (LUT) elements in logic circuits of Mealy finite state machines (FSMs). The FSMs with twofold state assignment are discussed. The reduction is achieved due to using two cores of LUTs for generating partial Boolean functions. One core is based on maximum binary state codes. The second core uses extended state codes. Such an approach allows reducing the number of LUTs in the block of state codes' transformation. The proposed approach leads to LUT-based Mealy FSM circuits having three levels of logic blocks. Each partial function for any core is represented by a single-LUT circuit. A formal method is proposed for redistribution of states between these cores. An example of synthesis is shown to explain peculiarities of the proposed method. An example of state redistribution is given. The results of experiments conducted with standard benchmarks show that the double-core approach produces LUT-based FSM circuits with better area-temporal characteristics than they are for circuits produced by other investigated methods (Auto and One-hot of Vivado, JEDI, and twofold state assignment). Both the LUT counts and maximum operating frequencies are improved. The gain in LUT counts varies from 5.74% to 36.92%, and the gain in frequency varies from 5.42% to 12.4%. These improvements are connected with a very small growth of the power consumption (less than 1%). The advantages of the proposed approach increase as the number of FSM inputs and states increases. [ABSTRACT FROM AUTHOR]

The main contribution of this paper is a novel design method reducing the number of look-up table (LUT) elements in the circuits of three-block Mealy finite-state machines (FSMs). The proposed method is based on using codes of collections of outputs (COs) for representing both FSM state variables and outputs. The interstate transitions are represented by output collections generated during two adjacent cycles of FSM operation. To avoid doubling the number of variables encoding of COs, two registers are used. The first register keeps a code of CO produced in the current cycle of operation; the code of a CO produced in the previous cycle is kept in the second register. There is given a synthesis example with applying the proposed method. The results of the research are shown. The research is conducted using the CAD tool Vivado by Xilinx. The experiments prove that the proposed approach allows reducing the hardware compared with such known methods as auto and one-hot of Vivado, and JEDI. Additionally, the proposed approach gives better results than a method based on the simultaneous replacement of inputs and encoding of COs. Compared to circuits of the three-block FSMs, the LUT counts are reduced by an average of 7.21% without significant reduction in the performance. Our approach loses in terms of power consumption (on average 9.62%) and power–time products (on average 10.44%). The gain in LUT counts and area–time products increases with the increase in the numbers of FSM states and inputs. [ABSTRACT FROM AUTHOR]

A method is proposed which aims to reduce the hardware in FPGA-based circuits of Mealy finite state machines (FSMs). The proposed method is a type of structural decomposition method. Its main goal is the reducing the number of look-up table (LUT) elements in FSM circuits compared to the three-block FSM circuit. The main idea of the proposed method is the using codes of collections of FSM outputs for replacing the FSM inputs and state variables. The interstate transitions are defined using collections of outputs generated in two adjacent cycles of synchronization. One, of output collection codes, is kept into a register. To optimize block-generating FSM outputs, a new type of state codes is proposed. A state is encoded as an element of some class of states. This approach allows both the number of logic levels and inter-level interconnections in LUT-based FSM circuit to be diminished. An example of an LUT-based Mealy FSM circuit with the proposed method applied is shown. Moreover, the results of our research are represented. The research was conducted using the CAD tool Vivado by Xilinx. The experiments prove that the proposed approach allows the reduction of hardware compared with such known methods as Auto and One-hot of Vivado, and JEDI. Moreover, the proposed approach gives better results than a method based on the simultaneous replacement of inputs and encoding collections of outputs. Compared to circuits of the three-block FSMs, the LUT counts are reduced by an average of 10.07% without significant reduction in the value of operating frequency. The gain in LUT counts increases with the increasing the numbers of FSM states and inputs. [ABSTRACT FROM AUTHOR]

Modern digital systems can be viewed as compositions of combinational and sequential blocks. In the article, we discuss a case when sequential blocks are represented using a model of Mealy finite-state machine (FSM). It is very important to improve such FSM characteristics as the number of used logic elements, operating frequency and power consumption. This article proposes a novel design method which allows diminishing the number of look-up table (LUTs) and increasing the operating frequency of multilevel LUT-based Mealy FSMs. The method is based on simultaneous use of such methods of structural decomposition as the transformation of states into FSM outputs and twofold state encoding. The proposed method results in three-level logic circuits of Mealy FSMs with regular systems of interconnections. Each function for any level of logic is implemented using a single LUT. An example of FSM synthesis with the proposed method is given. The experiments with standard benchmarks were conducted. The results of experiments show that the proposed approach leads to decreasing LUT counts from 11.9% to 62.6%. Also, it leads to increasing the operating frequency from 11.77% to 18.43% on average compared with other investigated approaches (Auto and One-hot of Vivado, JEDI, and replacement of FSM inputs and encoding the collections of outputs). The economy in used LUTs and gain in operating frequency grow with the growth of the FSM complexity. [ABSTRACT FROM AUTHOR]

A method is proposed for optimizing circuits of sequential devices which are used in cyber-physical systems (CPSs) implemented using field programmable gate arrays (FPGAs). The optimizing hardware is a very important problem connected with implementing digital parts of CPSs. In this article, we discuss a case when Mealy finite state machines (FSMs) represent behaviour of sequential devices. The proposed method is aimed at optimization of FSM circuits implemented with look-up table (LUT) elements of FPGA chip. The method aims to reduce the LUT count of Mealy FSMs with extended state codes. The method is based on finding a partition of the set of internal states by classes of compatible states. To reduce LUT count, we propose a special kind of state codes named composite state codes. The composite codes include two parts. The first part includes the binary codes of states as elements of some partition class. The second part consists of the code of corresponding partition class. Using composite state codes allows us to obtain FPGA-based FSM circuits with exactly two levels of logic. If some conditions hold, then any FSM function from the first level is implemented by a single LUT. The second level is represented as a network of multiplexers. Each multiplexer generates either an FSM output or input memory function. An example of synthesis is shown. The experiments prove that the proposed approach allows us to reduce hardware compared with two methods from Vivado, JEDI-based FSMs, and extended state assignment. Depending on the complexity of an FSM, the LUT count is reduced on average from 15.46 to 68.59 percent. The advantages of the proposed approach grow with the growth of FSM complexness. An additional positive effect of the proposed method is a decrease in the latency time. [ABSTRACT FROM AUTHOR]

One of the very important problems connected with FPGA-based design is reducing the hardware amount in implemented circuits. In this paper, we discuss the implementation of Mealy finite state machines (FSMs) by circuits consisting of look-up tables (LUT). A method is proposed to reduce the LUT count of three-block circuits of Mealy FSMs. The method is based on finding a partition of set of internal states by classes of compatible states. To reduce the LUT count, we propose a special kind of state code, named complex state codes. The complex codes include two parts. The first part includes the binary codes of a state as the element of some partition class. The second part consists of the code of corresponding partition class. Using complex state codes allows obtaining FPGA-based FSM circuits with exactly four logic blocks. If some conditions hold, then any FSM function from the first and second blocks is implemented by a single LUT. The third level is represented as a network of multiplexers. These multiplexers generate either additional variable encoding collections of outputs or input memory functions. The fourth level generates FSM outputs. An example of synthesis and experimental results is shown and discussed. The experiments prove that the proposed approach allows reducing hardware compared to such methods as auto and one-hot of Vivado, JEDI. Further, the proposed approach produces circuits with fewer LUTs than for three-level Mealy FSMs based on joint use of several methods of structural decomposition. The experiments show that our approach allows reducing the LUT counts on average from 11 to 77 percent. As the complexity of an FSM increases, the gain from the application of the proposed method grows; the same is true for both the FSM performance and power consumption. [ABSTRACT FROM AUTHOR]

Very often, a digital system includes sequential blocks which can be represented using a model of the finite state machine (FSM). It is very important to improve such FSM characteristics as the number of used logic elements, operating frequency and consumed energy. The paper proposes a novel technology-dependant design method targeting LUT-based Mealy FSMs. It belongs to the group of structural decomposition methods. The method is based on encoding the product terms of Boolean functions representing the FSM circuit. To diminish the number of LUTs, a partition of the set of internal states is constructed. It leads to three-level logic circuits of Mealy FSMs. Each function from the first level requires only a single LUT to be implemented. The method of constructing the partition with the minimum amount of classes is proposed. There is given an example of FSM synthesis with the proposed method. The experiments with standard benchmarks were conducted. They show that the proposed method can improve such FSM characteristics as the number of used LUTs. This improvement is accompanied by a decrease in performance. A positive side effect of the proposed method is a reduction in power consumption compared with FSMs obtained with other design methods. [ABSTRACT FROM AUTHOR]

Very often, digital systems include sequential blocks which can be represented using a model of Mealy finite state machine (FSM). It is very important to improve such FSM characteristics as the number of used logic elements, operating frequency and power consumption. The paper proposes a novel design method optimizing LUT counts of LUT-based Mealy FSMs. The method is based on simultaneous use of such methods of structural decomposition as the replacement of FSM inputs and encoding of the collections of outputs. The proposed method results in three-level logic circuits of Mealy FSMs. These circuits have regular systems of interconnections. An example of FSM synthesis with the proposed method is given. The experiments with standard benchmarks were conducted. The results of experiments show that the proposed approach leads to reducing the LUT counts from 12% to 59% in average compared with known methods of synthesis of single-level FSMs. Furthermore, our approach provides better LUT counts as compared to methods of synthesis of two-level FSMs (from 9% to 20%). This gain is accompanied by a small loss of FSM performance. [ABSTRACT FROM AUTHOR]

A method is proposed targeting implementation of FPGA-based Mealy finite state machines. The main goal of the method is a reduction for the number of look-up table (LUT) elements and their levels in FSM logic circuits. To do it, it is necessary to eliminate the direct dependence of input memory functions and FSM output functions on FSM inputs and state variables. The method is based on encoding of the terms corresponding to rows of direct structure tables. In such an approach, only terms depend on FSM inputs and state variables. Other functions depend on variables representing terms. The method belongs to the group of the methods of structural decomposition. The set of terms is divided by classes such that each class corresponds to a single-level LUT-based circuit. An embedded memory block (EMB) generates codes of both classes and terms as elements of these classes. The mutual using LUTs and EMB allows diminishing chip area occupied by FSM circuit (as compared to its LUT-based counterpart). The simple sequential algorithm is proposed for finding the partition of the set of terms by a determined number of classes. The method is based on representation of an FSM by a state transition table. However, it can be used for any known form of FSM specification. The example of synthesis is shown. The efficiency of the proposed method was investigated using a library of standard benchmarks. We compared the proposed with some other known design methods. The investigations show that the proposed method gives better results than other discussed methods. It allows the obtaining of FSM circuits with three levels of logic and regular interconnections. [ABSTRACT FROM AUTHOR]

A method is proposed targeting the decrease of the number of look-up tables (LUTs) in logic circuits of field programmable gate arrays (FPGA)-based Mealy finite state machines. The method is based on constructing a partition for the set of output variables. It diminishes the number of additional variables encoding the collections of output variables (COVs). A formal method is proposed for finding the partition. An example of synthesis is given, as well as the results of investigations. The investigations were conducted for standard benchmarks. [ABSTRACT FROM AUTHOR]

The complexity of algorithms implemented in digital systems grows. Methods are developed for most effective use of both hardware resources and energy. For engineers the problem of hardware resources optimization in design of control units is still an important issue. The standard way of implementing the control unit as a finite-state machine (FSM) is not satisfactory as it consumes considerable amounts of field-programmable gate arrays (FPGA) resources. This paper is devoted to the design of a Moore FSM in FPGA structure using look-up tables and embedded memory blocks (EMB) elements. The problem background is discussed. The method of the design of Moore FSM logic circuits with EMB based on splitting the set of logical conditions and the encoding of logical conditions is presented. Examples of design and research results are given. [ABSTRACT FROM AUTHOR]

Distributed embedded systems have become larger, more complex and complicated. More often, such systems operate accordingly to the IoT or Industry 4.0 concept. However, large number of end modules operating in the system leads to a significant load and consequently, to an overload of the communication interfaces. The CloudBus protocol is one of the methods which is used for data exchange and concurrent process synchronization in the distributed systems. It allows the significant savings in the amount of transmitted data between end modules, especially when compared with the other protocols used in the industry. Nevertheless, basic version of the protocol does not protect against the system failure in the event of failure of one of the nodes. This paper proposes four novel variants of the CloudBus protocol, which allow the fault detection. The comparison and performance analysis was executed for all proposed CloudBus variants. The verification and behavior analysis of the distributed systems were performed on SoC hardware research platform. Furthermore, a simple test application was proposed. [ABSTRACT FROM AUTHOR]

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A new two-stage method of finite state machines (FSMs) synthesis for PAL-based complex programmable logic devices (CPLD) is proposed. It is based on both the wide fan-in of PAL cells and existence of the classes of pseudoequivalent states of Moore FSM. The first step targets decreasing for the number of PAL cells used for implementing the block of input memory functions. The second step targets decreasing for the number of PAL cells in the block of microoperations. An example of application of the proposed method is given, as well as results of experiments carried out for standard benchmarks. [ABSTRACT FROM AUTHOR]

The methods are proposed targeting to reduce the numbers of both look-up table elements and embedded memory blocks in the logic circuit of a Moore finite state machine. The proposed methods are based on binary encoding of both classes of pseudoequivalent states and collections of microoperations. Examples of synthesis and results of investigations are given. [ABSTRACT FROM AUTHOR]

Optimization methods of logic circuits for Moore finite-state machines are proposed. These methods are based on the existence of pseudoequivalent states of a Moore finite-state machine, a wide fan-in of PAL macrocells and free resources of embedded memory blocks. The methods are oriented to hypothetical VLSI microcircuits based on the CPLD technology and containing PAL macrocells and embedded memory blocks. The conditions of effective application of each proposed method are shown. An algorithm to choose the best model of a finite-state machine for given conditions is proposed. Examples of proposed methods application are given. The effectiveness of the proposed methods is also investigated. [ABSTRACT FROM AUTHOR]

The review is devoted to methods of structural decomposition that are used for optimizing characteristics of circuits of finite state machines (FSMs). These methods are connected with the increasing the number of logic levels in resulting FSM circuits. They can be viewed as an alternative to methods of functional decompositions. The roots of these methods are analysed. It is shown that the first methods of structural decomposition have appeared in 1950s together with microprogram control units. The basic methods of structural decomposition are analysed. They are such methods as the replacement of FSM inputs, encoding collections of FSM outputs, and encoding of terms. It is shown that these methods can be used for any element basis. Additionally, the joint application of different methods is shown. The analysis of change in these methods related to the evolution of the logic elements is performed. The application of these methods for optimizing FPGA- based FSMs is shown. Such new methods as twofold state assignment and mixed encoding of outputs are analysed. Some methods are illustrated with examples of FSM synthesis. Additionally, some experimental results are represented. These results prove that the methods of structural decomposition really improve the characteristics of FSM circuits. [ABSTRACT FROM AUTHOR]

Practically, any digital system includes sequential blocks. This article is devoted to a case when sequential blocks are represented by models of Mealy finite state machines (FSMs). The performance (maximum operating frequency) is one of the most important characteristics of an FSM circuit. In this article, a method is proposed which aims at increasing the operating frequency of LUT-based Mealy FSMs with twofold state assignment. This is done using only extended state codes. Such an approach allows excluding a block of transformation of binary state codes into extended state codes. The proposed approach leads to LUT-based Mealy FSM circuits having two levels of logic blocks. Each function for any logic level is represented by a circuit including a single LUT. The proposed method is illustrated by an example of synthesis. The results of experiments conducted with standard benchmarks show that the proposed approach produces LUT-based circuits with significantly higher operating frequency than it is for circuits produced by other investigated methods (Auto and One-hot of Vivado, JEDI, twofold state assignment). The performance is increased by an average of 15.9 to 25.49 percent. These improvements are accompanied by a small growth of the numbers of LUTs compared with circuits based on twofold state assignment. Our approach provides the best area-time products compared with other investigated methods. The advantages of the proposed approach increase as the number of FSM inputs and states increases. [ABSTRACT FROM AUTHOR]