Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 24 Sep 2012 11:27:11 -0500

Hi Lewis,

On 2012-09-24 J. Lewis Muir wrote:
> I think it's nicer if ifdefs can be avoided.  Another approach
> might be to try using the "%c" format specifier to match just
> one char.  Maybe it works correctly on Windows when preceded by
> a space in the format string?
> 
> Or, there's also strtoul.  This will allow leading white space,
> but you'd have to check the end pointer to allow trailing white
> space (since with trailing white space it would not point to a
> NUL char).

I would prefer to avoid ifdefs in this situation.  I added a set of APIs to 
epicsStdlib.h in the R3.15 tree for doing string to integer conversions.  They 
call strtol() or strtoul() and check for numeric overflow of the various 
different type sizes, allow you to say whether you're looking for a trailing 
string (units say) or not, and return a status/error code.  I have a branch 
which uses this API for all string conversions in dbConvert.c and dbFastConv.c 
but I haven't merged it because it changes the conversion behavior of the IOC 
in subtle ways.  For example numeric overflow used to cause value truncation, 
but with this API the conversion fails instead.

One of Marty's regression tests for Base runs a series of conversions between 
all the different types using both DB and CA links and outputs the results as 
a large file.  The actual output has always varied between targets, OSs and 
versions of Base, and I have never completely managed to explain all the 
differences to my own satisfaction. The above branch definitely changes the 
output from this test, although I believe it makes the different targets & OSs 
behave more similarly than they used to.

I would be interested in other people's views on conversion behavior by the 
IOC (what it should do, not so much how it should be implemented).

- Andrew
-- 
Never interrupt your enemy when he is making a mistake.
-- Napoleon Bonaparte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System