I guess saying that "printf is part of the standard C library, not
affiliated with any
particular operating system" probably needs a little clarification.
This library was of course first designed for unix, but has also been
used in other OSs since. TinyOS is no different.
Kevin
On 9/21/07, Kevin Klues <[EMAIL PROTECTED]> wrote:
> I don't seen anything in 'man 3 printf' that implies that it has to be
> a blocking operation. In fact the manual shouldn't imply this.
> printf is part of the standard C library, not affiliated with any
> particular operating system.
>
> To implement printf() functionality for any mcu that has a libc (such
> as msp430-libc or avr-libc) you just have to fill in the body of the
> 'putchar' function declared in "stdio.h". This is exactly what the
> PrintfP component in tos/lib/printf does. No magic..... it just
> collects the bytes coming in via calls to putchar, packs them into
> TInyOS serial messages, and sends them out over the USART.
>
> It should be left up to whatever operating system that implements it
> to define the semantics.
>
> Kevin
>
> On 9/21/07, Philip Levis <[EMAIL PROTECTED]> wrote:
> > On Sep 21, 2007, at 5:56 PM, Michael Schippling wrote:
> >
> > > Does 'regular' printf() guarantee that now?
> > > I remember having to do fflush() if I really wanted to see something.
> >
> > C stdlib printf(3) does not always block. But it can block, and you
> > can make it block on flushing the buffer.[1] This might seem like a
> > little nit, but it can bite you. E.g.:
> >
> > call Foo.x();
> > printf("Got past Foo.x()\n");
> > call Foo.y();
> > printf("Got past Foo.y()\n");
> >
> > Phil
> >
> > [1] http://books.google.com/books?
> > id=iRa-3L4jLhEC&pg=PA84&lpg=PA84&dq=printf+flush+newline
> > +buffer&source=web&ots=dWntcq9i9J&sig=_r66dlfabrAEkJ8ltMzuRLysKj4
> >
>
>
> --
> ~Kevin
>
--
~Kevin
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