I want to participate in GSoC from RTEMS

[Joel Sherrill]

Madhusudan C.S wrote:
>
> Hi all,
>         I am a student who want to participate in GSoC as a RTEMS 
> student. I have been seeing the list of ideas from quite a few days. 
> Most of the ideas look interesting. I am pretty confused to choose an 
> idea to work on this summer. I am extremely interested in the "Add 
> 64-bit Timestamps" idea. Frankly speaking I have a fair knowledge of 
> C. But I haven't worked practically on any of the RTOS. But know the 
> theoritical concepts. So can someone help to do a bit of brainstorming 
> since I am very much interested in working with RTEMS this summer 
> especially after seeing RTEMS wiki, its principles and philosophies
>
That project in particular requires more knowledge of C and more attention
to detail than deep algorithmic knowledge.  Remember the issue is that
RTEMS used to have all time based upon clock ticks, then we added nanosecond
time granularity and kept the time in structure timespec.  It isn't easy or
particularly efficient to do math on struct timespec so this project is
adding the capability to configure on a per-target basis 64-bit time.  
You do
have to implement it but since the math will be on the native type 
"unsigned
long long" instead of int or long, that part isn't rough.

The rougher side of the effort is in adding a supercore (cpukit/score)
timestamp handler (e.g. roughly an opaque C "class") and going through
the supercore and using that instead of struct timespec where appropriate.

As the Wiki description states, some times need to be native, others have to
be in API formats.  Each case has to be evaluated so the conversions are
minimized.

Follow the code from one of the clock get time or set time routines down the
layers to the lowest core methods and you will get a feel.  You will see 
routines
with "convert" in their name or a name like "from XXX" or "to XXX" as 
the names.
Start at cpukit/rtems/src/clockset.c for one case.  There are similar 
routines
in cpukit/posix/src/clock*.c

Does that make sense at all?


>
>   Thanks and regards,
>  Madhusudan.C.S
>


-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
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