Software Coding Standards

Where bespoke software needs to be developed to meet the URS, a detailed design is required. Often, however, bespoke software is developed within the RAD phase in the absence of software coding standards and configuration controls. This does not overcome the need for a fully documented design. 

In order to ensure the development of safe application software, coding standards should be... 

Operating system code availability Software/hardware specifications Software/hardware design practices Product design records Program coding standards System development records System test records Programming tools Control of nonoperational software Removal of dead code ... 

Ensure that the software code or configuration is to a standard that will ensure clear understanding and support maintenance and modification of the software throughout the system validation life cycle... 

Gather the requirements for the systems including functional (e.g. operational checks) requirements, nonfunctional (e.g., coding standards) requirements, users, company-wide regulatory compliance (e.g., Part 11 technical control), safety, process, and other applicable requirements Characterize information, assess its value to the organization, and incorporate information quality as part of the project plan Conduct a system (hardware, software, and process) risk analysis. New requirements may be found as the result of the risk analysis. Any new requirements must be documented in the requirements specification deliverable... 

Code audits are formal and independent reviews of source code by a person, a team, or tool, to verify its compliance with software design documentation and programming standards. In addition, the software code is evaluated against its supporting documentation to ensure that it correctly describes the code. 

Establish and document the standards to be used for all Web site development following the same approach used for other coding standards within the software development life cycle. 

The majority of analytical processes in regulated environments rely on computer control for automation and for data capture and evaluation. It is therefore important that not only is the instrument validated but also the computer and operational software. Validation of software is more complex than hardware validation, especially since source codes for many analytical processes can run to several hundred thousand lines. In this case the responsibility for validation still remains with the user, who should have the assurance that the computer system has been validated during and at the end of the DQ phase. The vendor should provide documentation with a declaration that the software has been validated to these or similar guidelines to ensure software quality standards. Further, the vendor should provide access to the source codes if required by the user. 

Where there is a greater need for bespoke software development, the implementation (coding) must be controlled by coding standards. A t5q)ical coding standard will address the following ... 

An example of a coding standard used by the SIS logic solver programmers is also discussed in Clause D.3. Clause D.4 discusses additional requirements that should be considered for the software development tools. 

Static Code Analysis (SCA) has a proven track record as a powerful software verification technique providing the necessary rigour for safety-related software. A number of mature tools supporting SCA are available. However, static analysis also has a reputation as being costly and labour-intensive. This paper looks at recent advances in identifying objectives and processes for SCA and assesses the potential for such analyses to provide, in conjunction with new software safety standards such as the CAA s SWOl and Ministry of Defence s DEF STAN 00-56 Issue 3, a cost-effective and focussed method of gathering evidence that software performs safely. 

Two types of SC A are apparent, syntactic and semantic analysis and these are used for two purposes demonstration of code integrity and functional correctness. Syntactic Analysis is based on the structure of the code and has the ability to detect control flow errors (e.g. unreachable code), data flow errors (e.g. an OUT parameter that is not always written) and coding standard violations. Additionally a syntactic technique. Information Flow analysis, can be used to support software partitioning arguments by demonstrating that sections of code are independent of each other. Syntactic Analysis can also be used to measure software and generate software metrics, though these tend to be relatively simple metrics such as McCabe s complexity metric. 

PL for development of safety-related software shall be based on a PL coding standard that specifies good programming practices (for PL features see later). 

Hazard I has obvious applications for writing fire-code standards and could be useful for establishing liability in fires involving fatalities. It can also be used by compounders to predict the performance of developing FR plastics and to compare plastics. This software package is available from the National Fire Protection Association, Batterymarch Park, Quincy, Massachusetts, 02269. 

Boogerd, C. Moonen, L. (2009). Evaluating the relation between coding standard violations and faults within and across software versions, 6th Working Conference on Mining Software Repositories (MSR 09) pp. 41-50. 

Object code verification. Finally, when the control system model has been compiled into object code, it should be verified that the object code correctly implements the control system model. This process can be automated by tools that should also be provided by the framework. Automated object code verification for safety-critical control systems is motivated by the fact that applicable standards for these safety-critical applications, e.g. for railways [3], require a substantial justification with respect to the consistency between high-level software code and the object code generated by the applied compilers. 

The source code is generated from C-code templates. The templates were implemented manually by a software engineer and capture the typical implementation patterns for software safety requirements. They take into account properties of the software safety requirements, e.g., buffers, ranges and specified reactions and are defined having in mind properties such as ISO 26262 requirements on coding standards (i.e., MISRA C [15]). 

The implementation phase consists of the software constraction and software integration processes. Both include adequate test activities like component tests and integration tests. The software architecture, the interface specifications and the defined coding standards are iiqmts for the software coding process. Some complex software projects demand for more detailed component designs fiom which the source code can be directly derived and implemented. This phase is completed when all relevant requirements are irrqilemented, integrated and tested. Also here, traceability to all the previous phases is demanded. 

Seeing the success of the UNAMAP BBS, EPA s Office of Air Quality Planning and Standards started a BBS for information on regulatory models in June 1989. This has expanded to a BBS called TTN, Technology Transfer Network. This BBS, in Durham, NC, is reached on (919) 541-5742 and the system operator on (919) 541-5384. A part of this BBS called SCRAM, Support Center for Regulatory Air Models, contains model FORTRAN codes, model executable codes for use on personal computers, meteorological data, and in some cases model user s guides. Much of the information is downloaded in "packed" form, and software to unpack the files must also be downloaded from the bulletin board. 

Sponsor/Developing Organization LLNL. Developer. Laurence E. Fried LLNL, P.O. Box 808 Livermore, CA 94551, E-mail cheetah llnl.gov. Hardware-. IBM-PC or clone, Windows 3.1, Windows 95, Mac OS 7.x or later, SUN and SGI workstations, 4.3 MB of hard disk. Software ANSI C. Run execution time for typical problem (CPU or real time). Standard run About 30 seconds on a Power Macintosh 6100/80. Cost None from LLNL. Source code is available, with the stipulations that all modifications be preapproved and forwarded to the sponsor for tracking... 

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