Embedded experts: Fix code bugs or cost lives

For instance, C doesn't define the number of bits in a byte, though header files can query a processor and adjust the program if the CPU does not support the usual 8-bit byte. Likewise, the common practice of subtracting pointers can result in creating a character of an undefined type, said Saks, president of consulting firm Saks & Associates (Springfield, Ohio).

"The use of C is really criminal," said Ganssle. "C will compile a telephone directory, practically. I guess we use C because we think debugging is fun."

For every 1,000 lines of code, C can generate 500 errors in a worst case, 167 errors on average or 12.5 mistakes for automatically generated code, said Ganssle. That compares with 50 errors worst case, 25 average and 4.8 for auto-generated code using the Ada language, he said. The Spark language emerging from Europe is even better, generating just four errors on average per 1,000 lines of code, he claimed.

C is used in half the development projects done today, according to the results from the 2006 Embedded Market Survey, the 14th such annual poll of engineers working on embedded-design projects. The survey showed that the C++ programming language is gaining in acceptance, however.

ESD editor-in-chief Jim Turley, who presented the annual embedded-market survey results last week, said fully half of the respondents cited C as their primary programming language. Nonetheless, support for C was down from the 2005 survey, albeit only by 3 percent. By contrast, the C++ language gained this year, coming in at 28 percent, and respondents predicted a 4 percent increase in C++ adoption next year.

The survey showed that relatively few engineers — just a few percent — use Java. Matlab, LabView and UML are used about as frequently for embedded projects, although Java garners more attention because of its use in the graphical user interface portion of many systems.

"Almost every language is losing ground to C++," said Turley, who suggested that many design teams have evaluated Java but found it lacking in performance and development tools.

Asked about tool selection, 53 percent of embedded engineers said the quality of the debugger was their most important criterion in choosing a development suite. Only about 13 percent said open-source content is an important selection criterion.

When it comes to operating systems, however, open-source OSes such as Linux are gaining significant support. Fully 20 percent of respondents said they use an open-source OS, with many design teams relying on a commercially distributed form of Linux.

Turley said that one reading of the operating system responses would suggest Linux is gaining support quickly, since "just five years ago the very term 'open source' didn't mean anything." However, other survey questions showed that a declining number of respondents, compared with the 2005 survey, are considering Linux, prompting Turley to conclude that "that the charm of Linux has cooled."

Management must take its share of the blame for the software situation. "Often we are in an overconstrained situation. We have too many features to deliver in too short a time frame," said Fowler at his "Fantastic Failures" session. "The problem is, adding features requires lots of regression testing. The thing to do is ask whether the feature can be saved for the next upgrade — [otherwise] you are just setting yourself up for failure.

"We as engineers need to come up with persuasive ways to warn management" by relating stories of past failures or the implications of long feature lists and tight budgets and schedules, he added.

Tired engineers were a factor in several aerospace disasters in which programmers worked 60- to 80-hour weeks in the months before a launch, Ganssle said.

Skimpy budgeting is another factor in failures, as seen most clearly in civil-engineering disasters. In 1940, officials found a way to build the Tacoma Narrows Bridge for half an initial estimate and did so, but the bridge famously collapsed in high winds after just four months in service. Likewise, the MGM Grand Hotel in Las Vegas saved $200,000 by not using sprinklers but paid out more than $200 million in court and rebuilding costs after a disastrous fire, Ganssle said.

In the confines of a software project, "spending $2,000 on tools might save you $100,000 in programming effort," said Stewart of Embedded Research Solutions.