Re: [tlug] issues with format of double (or IEEE754)

["Stephen J. Turnbull" <stephen@example.com>]

>>>>> "Michal" == Michal Hajek <hajek1@example.com> writes:

    >> Did reading in ASCII, then converting with atof() work
    >> correctly?

    Michal> yes, it works well. No problem.

Eh!?  Are you resetting the mode of the nanovoltmeter?  If not, then
of course the other method doesn't work.

Also, I think it is very very strange that binary format has a header
that is not double-aligned.  The whole point of a binary format would
be speed (where "speed" means microseconds, not milliseconds), and
what you would want is a board with DMA, just stuffing an array of
doubles.  Even if you're stuffing the array by hand, the header is
pointless.

    Michal> But if I run the program in gdb, than my personal
    Michal> subjective impression is, that atof() takes considerably
    Michal> more time than for example ibrd().

There could be any number of reasons for that.  You need to write a
careful, realistic benchmark and test under load.

    Michal> This is difficult to say. The nanovoltmeter can make a
    Michal> conversion very quickly, but for my purpose about 16.6ms
    Michal> would be ok.

How fast is "very quickly"?

If atof() takes as much as 1ms to run, something is very very wrong.
This is not a system call, there should be no context switch or
anything like that.


-- 
School of Systems and Information Engineering http://turnbull.sk.tsukuba.ac.jp
University of Tsukuba                    Tennodai 1-1-1 Tsukuba 305-8573 JAPAN
               Ask not how you can "do" free software business;
              ask what your business can "do for" free software.