Re: [Dev-C++] how to update data constantly?

[Jessica C. <jes...@gm...>]

I don't understand this point.
I think a cheaper form of semaphore (whatever for Win32 application or Unix
application) is mutex.
A critical section is a piece of code which access a shared resource (like
data) of two threads.

Can you pls do a bit more explanation about your issue?

On Dec 6, 2007 5:43 AM, Per Westermark <pw...@ia...> wrote:

> A cheaper form of mutex for Win32 applications are the critical
> sections. In some situations a semaphore may be suitable.
>
> /pwm
>
> On Wed, 5 Dec 2007, Chris Miller wrote:
>
> > On Dec 5, 2007 1:10 PM, Jessica Chen <jes...@gm...> wrote:
> > > My whole projects have two thread.
> > > one thread is reading RS-232 communication port.
> > > another thread is Win32 GUI to display the data got from RS-232
> > > communication port.
> > >
> > > The design I had is:
> > > Buttons on Win32 GUI.
> > > So when the button is clicked, the corresponding data is read from
> RS232
> > > thread, and display in the GUI thread.
> > >
> > > BUT I want to have a constantly updated display.  That is, there is NO
> > > button to trigger the data update.
> > > When the data of RS232 thread is updated, my display of GUI thread
> need to
> > > be updated.
> > > What should I design?
> > >
> > > My consideration for the design is:
> > > add a constant interval timer to trigger the data update.
> > >  but how to implement it?
> > > and do you have any other good idea?
> >
> > A commonly used technique is to have the GUI thread check the reader
> > thread every X miliseconds.  This requires that you use a mutex to
> > lock the data while it's being read, otherwise you might incur the
> > wrath of undefined behavior when reading memory that's currently being
> > written to.
> >
> > What if you had a dual-core CPU, and you managed to send a read
> > request exactly when you sent a write request?  Something tells me
> > that's not possible because of the mutexes in the lower-level
> > implementation, but it would be interesting to see which request the
> > memory controller disregards.
> >
> >
> > I'm not sure how to implement a mutex in a Win32 thread, however,
> > pthreads is only a wrapper on top of Win32, so it can be done (I
> > didn't notice any special code in the pthreads sources when I glossed
> > over them).
> >
> > --
> > Registered Linux Addict #431495
> > http://profile.xfire.com/mrstalinman
> > John 3:16!
> > If Microsoft is the Wal*Mart of the Software World, then Linux is the
> Home Depot
> >
> >
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