Re: Translating an embedded C algorithm

["Talulah" <paul.hills@uk.landisgyr.com>]

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Jeffrey Carter wrote:

> Where the example came from should be irrelevant for a small example in
> a text.

It is irrelevant for the book, but not for the choice of language.

>Apparently you have a monopoly, since your share of the market
> in your calculations is the total market.

Our estimate is for 20% of this market. The same argument applies to
the resulting £100,000 profit as it would to a £500,000 profit. If we
did have a monopoly, price would not be an issue of course!

> Where we have hard data, they show that Ada reduces development costs by
> 1/2 over C, reduces post-deployment errors by 1/4, and reduces the cost
> to fix an error by 1/10.

I accept that may be the case. However, there are no Ada tools for very
many microcontrollers. The cost drives the choice of microcontroller,
and the microcontroller then drives the choice of development system.

> There is a least one documented case of Ada producing smaller code than
> hand-optimized assembler.

I love these statistics. There's a Java vendor who reckons the byte
code runs faster than C as well. You can prove anything if y0ou have
choice over the tools that you use to produce the results. This "hand
coded assembler" could mean anything - it could mean taking Ada
compiled code and ADDING instructions to it!

Thinking logically, if the assembler coder was any good, he can always
produce code of equal size to compiled code, and should always produce
tighter code. It just depends what he is trying to prove, and who has
sponsored him to do the work!

> Dewar has a number of examples of equivalent
> Ada and C code that produce identical object code.
> Thus, the assumption that C is necessary to keep costs down is
> unsupported, a fact that anyone qualified to choose the language for
> such SW should know.

When was the last time you wrote an Ada program to run on a
microcontroller such as a PIC or ATMega48, i.e. something around the
$0.50 price mark? And can you tell me a compiler vendor? C compilers
are available for both these devices. Therefore most embedded
developers (who are not in the military market and where cost is the
greatest issue) cannot choose the language they develop in.

> Finally, I did not assert that you are unqualified to write such a book.
> I said, "I have to wonder about the qualifications of someone who only
> knows C." I am perfectly willing to have it demonstrated that you are
> qualified.

Nit-picking. Fine distinctions. As I said before, most embedded
development IS doen in C, so that should be reflected in the book. The
fact that I want to show readers that other languages exist, and are
better for certain applications does not mean that I have to be an
expert in, or even know those other languages, especially when there
are so many very helpful posters to this thread that have made useful
suggestions.