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
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