A network-oriented language—A new approach to network design, using interactive graphics

A language is proposed for the design of any network, using interactive graphics as an aid to the design process. The language, NOL-1, is a higher level problem-oriented programming language. It is based on the network definition language NEDLAN (see [1] and [8]) and associated mechanisms, and it incorporates definition, decision and control, dynamic graphical input and output and analysis statements.

Combining all these statement types with due regard to ergonomic factors in the use of interactive graphics for designing networks, a network-oriented higher level language to be used with interactive graphics is obtained.     

Chicon—a Chinese text manipulation language

Text processing is an important computer application. Due to its importance, a number of text manipulation programming languages have been devised (e.g. Icon). These programming languages are very useful for applications such as natural language processing, text analysis, text editing, document formatting, text generation, etc. However, they were mainly designed to handle English texts, and are ineffective for Chinese. This is because English and Chinese texts are represented very differently in a computer. An English character is mainly represented in 7-bit ASCII, and its Chinese counterpart commonly in 16-bit GB or BIG-5. This difference makes direct application of English-based text manipulation programming languages to Chinese erroneous, e.g. application of Icon to reverse a string of Chinese characters. In this paper, a new dialect of Icon, referred to as Chicon (i.e. Chinese Icon), is proposed. In the design of Chicon, new data types were introduced to differentiate pure English and English/Chinese mixed texts. In addition, existing Icon text manipulation functions were modified to account for Chinese texts. Experiments have shown that Chicon not only could overcome the problems of Chinese processing in Icon, but its execution speed was actually superior to Icon in handling Chinese. Furthermore, application of Chicon to a real sized problem, namely word segmentation, has proved that the language is practical. © 1998 John Wiley & Sons, Ltd.     

Implementation of a Capability-Based Data Abstraction

One important feature in programming language design is an appropriate data definitional facility. Criteria now recognized as important are the concepts of information hiding and data abstraction. The problem, however, is to embed these ideas into languages. Although including these ideas has often led to the design of a new language, that is not always necessary. Such facilities may be added to languages like PL/1 or Pascal. This report discusses the inclusion of such facilities within one such PL/1 compiler. While the resulting system does not have the optimal set of protection features, it does have several advantages: the base language is known to a large class of programmers, there are many such compilers already written, and the system achieves almost as much protection as is needed.     

A framework for modelling graphic interactions

In the present-day graphics field, a proper methodology for designing input constructs of a general purpose graphics system is needed. In this direction, this paper proposes a framework where the graphics interaction programming is formulated as event-driven procedures. The end-user actions on the input tools are represented as events and the programreactions to these events as action-processes. The constructs for programming in this framework are implemented as a part of a graphics package SODDI. The resultant programming facilities are compared with the other existing proposals, based on the conceptual differences of the respective frameworks as well as on the experiences in using the constructs. The data-structures used for implementing these constructs are also presented.     

Developments of CAD in civil engineering reviewed

Substantial progress has been made during the past decade in making the computer an effective analytical tool for the design engineer. However more recent development has concentrated on various features of a design offices final product. These areas comprise production of construction drawings, interactive graphics, colour graphics, pre-and post-processing of input and output data, linking analysis programs to modular design programs to provide a rapid transfer of design to the latest code requirement, use of microcomputers and personal computers. There is also significant software development for site management, cost analysis, general administration and documentation related to construction. This takes advantage of the availability of cheaper hardware which can communicate with other computers elsewhere in a network. User interaction facilities are being built into programs which allow the engineer to concentrate on design decisions. This paper reviews the developments during the last two-three years in CAD in Civil Engineering.     

An Integrated Graphics Programming Environment

The facilities of the PS-algol programming language are described in this paper to show how they may be used to provide an integrated graphics programming environment. The persistent store mechanism and the secure transaction facilities of the language provide the basic environment in which an integrated system may be implemented. This is augmented by data types and operations to support line drawings and raster graphics. The combination of these mechanisms may be used to provide the integrated graphics programming environment.     

A simple system for constructing distributed,mixed-language programs

The Mixed-Language Programming (MLP) System is a simple system that facilitates construction of sequential programs in which procedures can be written in different programming languages to exploit heterogeneity in language functionality. In addition, MLP provides a simple remote procedure call (RPC) facility that allows heterogeneity in machine functionality to be exploited. To minimize implementation cost, the system does not solve all of the problems related to mixed-language programming; rather, MLP is designed to handle common situations well. Among the unique aspects of MLP are its advanced facilities, which allow complex situations to be handled with user intervention; for example, these facilities allow arguments of a type not defined by a language to be used by procedures written in that language. This paper overviews the use of MLP and describes its implementation. In addition, two programs that have been written using the MLP system—a small database system and a collection of plot routines—are discussed. The system executes on a collection of Vaxes and Suns running Berkeley UNIX. Currently supported languages are C, Pascal and Icon.     

An assessment of modula

Wirth has recently published a new programming language called Modula which he suggests is suitable for the programming of process control systems, computerized laboratory equipment and input/output device drivers. The authors have written a compiler for Modula running on a PDP-11 and generating object code for the same machine. Their experience in writing device drivers for a number of PDP-11 devices is reported, including simple mains frequency clocks, disks, CAMAC and a graphics processor. Some difficulties arose during the writing of these programs; these are investigated and solutions proposed, either within the existing language or by minor modifications to the language. The study shows the extent to which Modula meets the requirements for a general purpose real-time systems-implementations programming language; areas of deficiency are noted.     

Software Systems for Computer Graphics

This paper describes some software packages and programming systems for computer graphics applications, in the process considering software features for both passive and interactive graphics. It examines the structure both of subroutine libraries for use with some base language and of complete programming languages, and outlines the advantages and disadvantages of each, along with facilities that should be present in any software package.     

Logicon: An integration of prolog into icon

This paper describes the coupling of logic programming with Icon, which is a programming language aimed at string processing. Icon and Prolog have many similarities and their integration is feasible and desirable because the weaknesses of one can be compensated for by the strengths of the other. In our case, a Prolog interpreter was written as an Icon procedure that can be linked and called by an Icon program. This interpreter deals with all Icon data types and can be called in the context of the goal-directed evaluation of Icon. We give an example showing the power of this symbiosis between these two languages where a Prolog call in Icon is a generator and an Icon call in a Prolog clause is a built-in predicate.     

High-level goal-directed concurrent processing in icon

Concurrent language features have been added to an experimental dialect of Icon called Conicon. These new language features allow Icon to deal with new application domains such as intelligent robot control and real-time natural language processing. Besides widening the scope of Icon's intended application domain, these experimental concurrent processing notations also encourage programmers to revise existing programs to take advantage of the new language capabilities. For example, concurrent evaluation of the alternative arms of compound goal-directed expressions is now possible. This paper describes these concurrent processing notations and presents several examples of their expressive power.     

Building flexible real-time systems using the Flex language

The design and implementation of a real-time programming language called Flex, which is a derivative of C++, are presented. It is shown how different types of timing requirements might be expressed and enforced in Flex, how they might be fulfilled in a flexible way using different program models, and how the programming environment can help in making binding and scheduling decisions. The timing constraint primitives in Flex are easy to use yet powerful enough to define both independent and relative timing constraints. Program models like imprecise computation and performance polymorphism can carry out flexible real-time programs. In addition, programmers can use a performance measurement tool that produces statistically correct timing models to predict the expected execution time of a program and to help make binding decisions. A real-time programming environment is also presented     

Measuring the Performance and Behavior of Icon Programs

The importance of the ability to measure the performance of programs written in high-level languages is well known. Performance measurement enables users to locate and correct program inefficiencies where automatic optimizations fail and provides a tool for understanding program behavior. This paper describes performance measurement facilities for the Icon programming language, and shows not only how these facilities provided insight into program behavior, but also how they were used to improve the implementation.     

An operational semantics for Icon: Implementation of a procedural goal-directed language

The generation of compiled code for expressions in programming languages such as Icon that support goal-directed evaluation in addition to traditional control structures presents more of a challenge than generating code for traditional imperative programming languages. This paper describes a code-generation technique for translating Icon programs into a traditional high-level language. Translations into both Pascal and C are discussed. However, any language that provides function parameters and recursion is sufficient. The technique described here has been used in the implementation of an optimizing compiler for Icon.     

An optimizing compiler for the icon programming language

Compiling code for the Icon programming language presents several challenges, particularly in dealing with types and goal-directed expression evaluation. In order to produce optimized code, it is necessary for the compiler to know much more about operations than is necessary for the compilation of most programming languages. This paper describes the organization of the Icon compiler and the way it acquires and maintains information about operations. The Icon compiler generates C code, which makes it portable to a wide variety of platforms and also allows the use of existing C compilers for performing routine optimizations on the final code. A specially designed implementation language, which is a superset of C, is used for writing Icon's run-time system. This language allows the inclusion of information about the abstract semantics of Icon operations and their type-checking and conversion requirements. A translator converts code written in the run-time language to C code to provide an object library for linking with the code produced by the Icon compiler. The translation process also automatically produces a database that contains the information the Icon compiler needs to generate and optimize code. This approach allows easy extension of Icon's computational repertoire, alternate computational extensions, and cross compilation.     

A portable storage management system for the icon programming language

Icon is a new programming language designed primarily for non-numerical applications. Its roots are in SNOBOL4 and SL5; as in those languages, execution-time flexibility is an important attribute of Icon, although some aspects of programs are bound at compile time to improve efficiency. Icon, which is implemented in Ratfor, is also intended to be portable and suitable for 16-bit computers. The storage management system in Icon is designed to meet the goals of portability, flexibility and efficiency. This is accomplished by subdividing the storage management system into a set of type-specific storage management subsystems. This paper describes the implementation of these subsystems, their interaction, and their performance.     

Result sequences

Expression evaluation in conventional programming languages may be viewed as a simplification of expression evaluation in the Icon programming language. The evaluation of an expression in Icon may yield a sequence of results. Goal-directed evaluation causes expressions to produce these results in an attempt to produce the successful evaluation of an enclosing expression. There are control operations that operate on result sequences. The study of expression evaluation in Icon therefore is more interesting than it is in most programming languages. This paper introduces a notation for result sequences and shows how it can be used to describe the static aspects of expression evaluation. Equivalences among control operations and expressions are demonstrated.     

硬件加速的等值面提取与绘制

图形硬件的发展为通用计算提供了新的平台.利用图形硬件的高密集和并行运算能力,将非规则四面体网格数据映射为纹理,在GPU中从每个四面体提取等值面片,并将其绘制到纹理而得到最终等值面.基于Cg着色器编程语言实现三维雷达作用范围表现的实验结果表明:该方法有效的减轻了CPU负担,提高了等值面提取速度,适于实时应用.     

The use of a generic simulation model in evaluating manufacturing processes

In recent years the application of simulation models to analyze the production capabilities of manufacturing processes has been increasing at IBM's Poughkeepsie plant. To avoid major programming effort for each new application, a generic simulation model was developed. The model, written in SIMPL/1 (Simulation Language Based on PL/1), was designed in modules defined on a functional basis. This language was chosen because it allowed full use of the PL/1 programming language, reduced the excessive run times experienced with large, specialized GPSS models, simplified the procedure for making input changes and provided output that could be easily interpreted by the non-programmer. The input data bases are user-oriented so that changes can be made to the system being modeled without programming support. The output generated by the model can provide the user with information on resource utilization, major process bottlenecks, overtime requirements, process throughput and process cycle time. This data is evaluated by the user to determine how well the process functions under given operating conditions so that cost effective decisions can be made. An example is provided on the model's application to a logic and memory card assembly process.