Adam: An Ada-based language for multiprocessing

Adam is a high-level language for parallel processing. It is intended for programming resource scheduling applications, in particular supervisory packages for run-time scheduling of multiprocessing systems. An important design goal was to provide support for implementation of Ada and its run-time environment. Adam has been used to implement Ada task supervision and also as a high-level target language for compilation of Ada tasking. Adam provides facilities corresponding to the Ada sequential constructs (including subprograms, packages, exceptions, generics). In addition, it provides specialized module constructs for implementation of packages that may be shared between parallel processes, and new predefined types for scheduling. The parallel processing constructs of Adam are more primitive than Ada tasking. Strong restrictions are enforced on the ways in which parallel processes can interact. A compiler for Adam has been implemented in MacLisp on DEC PDP-10 computers. Runtime support packages in Adam for scheduling (on a single CPU) and I/O are also provided. The compiler contains a library manipulation facility for separate compilation. The Adam compiler has been used to build an Ada compiler for most of the July 1980 Ada, including task types and rendezvous constructs. This was achieved by implementing the translation of Ada tasking into Adam parallel processing as a preprocessor to the Adam compiler. This present Ada compiler, which has been operational since December 1980, uses a procedure call implementation of tasking. It can be easily modified to other implementations. Compilation of Ada tasking into a high-level target language such as Adam facilitates studying questions of correctness and efficiency of various compilation algorithms, and code optimizations specific to tasking, e.g. elimination of unnecessary threads of control. This paper gives an overview of Adam and examples of its use. Emphasis is placed on the differences from Ada. Experience using Adam to build the experimental Ada system is evaluated. Design of a run-time supervisor in Adam is discussed in detail.     

A parallel Ada system on an experimental multiprocessor

This paper describes the development of a parallel Ada system on an experimental MIMD multiprocessor. The system enables a single unmodified Ada program, with a number of tasks, to execute in parallel on different processors. Allocation and migration strategies are controlled by mechanisms in the run-time system, and are thus transparent to the Ada programmer. The parallel Ada system is based on a validated portable front-end compiler. Implementation issues related to the multiprocessor environment are pointed out, and solutions to these issues are suggested. The experimental multiprocessor environment, consisting of both hardware and software, is described. Applicable resource allocation strategies in, and feasible experiments with, the Ada system are discussed. The complete experimental system provides unique possibilities to experiment with, and monitor the effects of, design decisions at different levels in a multiprocessor environment.     

Two implementations of the Ada program library

The programming language Ada defines a separate compilation mechanism which must enforce the language rules in the same manner when compiling a program either in several units or as one compilation unit. Two implementations of the Ada program library required by this mechanism are described. Each has an associated compiler manager program which is the user's interface to the library. The first maintains a central map file containing the library structure. The second uses the UNIX tool make to maintain the library and permits more flexibility in the UNIX operating system environment. Higher level tools could use the second manager as a component part.     

The concurrency models of Ada and occam—a practical comparison

A comparison of the concurrency models of Ada and occam is presented. This comparison is performed in terms of an Ada-to-occam compiler. A subset of the Ada programming language may be compiled allowing a study of how programs and algorithms expressed using the Ada concurrency model can be mapped to the occam concurrency model. The resultant occam code may then be executed on a transputer. This paper describes the Ada and occam concurrency models, highlights the major differences between them, discusses the problems encountered in trying to map concurrent Ada programs to equivalent occam programs as a result of these differences and explains how these problems were overcome in the present compiler.     

Porting Ada: a report from the field

With the constant barrage of new systems, porting software applications is inevitable. This article takes a look at the problems involved in porting an Ada/C application. The porting effort begins when the software architecture is defined and the code implemented. The task is completed with the successful execution of the software on all target platforms. The AFATDS porting effort to the HP RISC platform was completed successfully. The effort to port AFATDS to an InteVSCO Unix platform is still incomplete and is awaiting an Ada compiler upgrade that can pass the AFATDS messaging schema's large arrays to generic procedures. With the numerous operating systems available, the constant barrage of new operating system releases, and the continual hardware advancements, the need to port software applications is evident. The success of any porting effort depends on the maturation and reliability of the tools being used. If the Department of Defense's dual-use strategy is to succeed, DoD must also foster the development of reliable and affordable Ada tools     

基于群机系统的Ada编译程序

为了使Ａｄａ程序运行在松散耦合分布式系统并且降低程度员开发分布Ａｄａ的程序的工,设计并实现了基于该环境下的Ａｄａ编译程序。     

The cyclic executive model and Ada

Periodic processes are major parts of many real-time embedded computer applications. The programming language Ada permits programming simple periodic processes, but it has some serious limitations; producing Ada programs with real-time performance comparable to those produced to date using traditional cyclic executives requires resorting to techniques that are specific to one machine or compiler. We present and evaluate the cyclic executive model for controlling periodic processes. The features and limitations of Ada for programming cyclic executive software are discussed and demonstrated, and some practical techniques for circumventing Ada limitations are described.     

编译基础设施中多目标编译技术探讨

从编译基础设施的基本概念出发，着重讨论了编译器后端构造所涉及的关键技术；比较全面地总结并评述了具有代表性的公共编译设施及春采用的中间表示技术、后端构造技术和相关工具；并探讨了编译器后端构造研究中存在的一些问题及相应的解决方案。     

Ada-Java编译器的研究与设计

Ｊａｖａ语言是近几年地出现的一种面向对象网络语言。     

Experience with multi-transputer Ada

The transputer is one of the most cost-effective multicomputer components to buy, but still one of the hardest to program. Even if the parts of a program that are destined for individual transputers are programmed in a familiar high-level language (Ada or Fortran or C), users are forced to be aware of occam when connecting transputers together with harnesses. Moreover, the design of parallel and distributed algorithms is in itself a challenging field. This paper describes experience with using the Alsys Ada compiler on single and multiple transputer configurations, and considers whether Ada makes it any easier to gain access to the power of multi-transputers. Early performance figures indicate that Ada running on transputer arrays compares favourably with the speed of other languages. An assessment of the impact of the proposed Ada 9X support for distribution is made.     

基于ALI的ADA语言静态分析器的研究与实现

Ada语言源代码经编译器编译后生成一个后缀名为Ali的文本文件。该Ali文件中包含了丰富的有关Ada源代码的信息。该文剖析了由M1750Ada编译器编译生成的Ali文件内包含的具体信息内容,并介绍了基于Ali文件的分析并结合Lex词法分析工具来实现ADA语言静态分析器的过程。     

Ada program partitioning language: a notion for distributing Adaprograms

Ada Program Partitioning Language (APPL) has been designed as part of Honeywell's Distributed Ada project. The goal of the project is to develop an approach for reducing the complexity of building distributed applications in Ada. In the proposed approach, an application is written as a single Ada program using the full capabilities of the Ada language. It is not necessary to factor the underlying hardware configuration into the program design. Once the program has been completed and tested in the host development environment, it is partitioned into fragments and mapped onto the distributed hardware. The partitioning and mapping are expressed in APPL and do not require changes to the Ada source. The main thrusts of the project include the design of APPL and the development of language translation tools and the run-time system to support Ada and APPL for a distributed target. The authors present an overview of APPL, the goals considered in the design, and issues that impact its implementation     

Validating a demonstration tool for graphics-assisted debugging ofAda concurrent programs

A demonstration-quality graphics-assisted debugger is developed for intertask communication in Ada. Based on the static task-specification diagrams of G. Booch (Software Engineering with Ada, Benjamin/Cummings, 1983), the debugger animates the activity of a collection of communicating tasks, and it runs on a DEC GIGI terminal connected to a VAX 11-780 under TeleSoft's partial Ada compiler. The model has been subjected to empirical validation, using undergraduate students as experimental subjects. Subjects were required to debug erroneous tasking programs using both the graphical debugger and a textual one. It is concluded that although the problems to be addressed in the development and evaluation of a graphical debugging tool for Ada tasks are nontrivial, the benefits could be worth the effort     

Experience acquiring and retargeting a portable Ada compiler

A technique for implementing Ada with reasonable effort on a piece of non-standard hardware is described. The target machine is a single processing element in an experimental multiprocessor based on NS32000. A portable Ada front-end compiler was used for retargeting, and the process of acquiring and evaluating the front end is described. Based on this experience, comments on the validation, quality and efficiency of Ada compilers are given, along with a detailed overview of the resultant system. The Ada system was built from scratch on the bare hardware. It has three main components: a code generator, a run-time system and an Ada kernel. The code generator is table driven and generates symbolic NS32000 assembler. This code is then assembled and linked by commercially available components. The run-time system and the kernel are implemented in assembly language and Concurrent Euclid and handle tasking, exceptions and scheduling. The result is a complete Ada implementation.     

Ada programming language standardization

The need for software management and standardization of programming languages used in military systems was first identified by DoD in 1975. DoD at that time supported many limited use languages for what are now called embedded computer applications. This diversity of languages contributed to high software costs. In November 1976, DoD first established seven approved , , , -J3, -J73, , -2, -1. Eventually the number of approved DoD languages may be reduced to three, Ada, , and . Ada was established as Military Standard 1815, on 10 December 1980. The ANSI standardization process for Ada is in progress. The Ada concept places restrictions on what may be called an Ada compiler. Compilers may not be called Ada compilers until they have passed validation tests. Up to 80% of software costs are incurred after the software has been put into service. Ada can promote a programming style that leads to maintainable software. It is in the program maintenance phase of the software life cycle where large savings will be achieved through the use of Ada.     

A LIS compiler for GCOS-7

This paper describes the implementation of a LIS compiler for GCOS-7. LIS is a high level system implementation language developed at CII-Honeywell Bull during the middle 1970s, and experience with the language and its implementation have largely influenced the design of Ada. The design of the compiler was particularly aimed at efficient code generation. Design decisions concerning the run-time organization in relation to procedure call and separate compilation are discussed. The structure of the compiler is described. The articulation between the different phases of the code generator is emphasized. Experience with the bootstrap is related.     

Ada95编译系统中多平台技术的研究

支持多语种、多平台是当前编译技术的发展趋势,它适应了当前计算机系统迅猛更新的需要。文中提出了一个适用于不同计算机平台的多平台Ada95编译系统的模型,在此基础上讨论了Ada95编译系统中多平台支持的三个关键技术:平台配置机制、运行库多平台支持技术和多平台代码生成支持策略,并描述了相应的设计与实现方法。     

Design and implementation of a Petri net based toolkit for Adatasking analysis

The use of Petri nets for defining a general static analysis framework for Ada tasking is advocated. The framework has evolved into a collection of tools that have proven to be a very valuable platform for experimental research. The design and implementation of tools that make up the tasking-oriented toolkit for the Ada language (TOTAL) are defined and discussed. Modeling and query/analysis methods and tools are discussed. Example Ada tasking programs are used to demonstrate the utility of each tool individually as well as the way the tools integrate. TOTAL is divided into two major subsystems, the front-end translator subsystem (FETS) and the back-end information display subsystem (BIDS). Three component tools that make up FETS are defined. Examples demonstrate the way these tools integrate in order to perform the translation of Ada source to Petri-net format. The BIDS subsystem and, in particular, the use of tools and techniques to support user-directed, but transparent, searches of Ada-net reachability graphs are discussed     

A portable virtual machine for Ada

A portable compiler can be constructed by letting it generate code for a virtual machine, which is then implemented on the real target machines. The design of a virtual machine which is especially suitable as a target machine for compiled Ada programs is described. The main design goals, implementability on mini-computers and portability, are discussed and the resulting design is described in some detail. Some implementation strategies for the machine are proposed and the feasibility of the virtual machine approach is discussed.