[ECOS] Problem with printf

[ECOS] Problem with printf

[Sidharth Jandhyala]

Hi,

I am having a peculiar problem with printf. I noticed that a newline '\n'
must be placed at the end of each printf statement to work. How do I get
around this problem? Here is s sample code

I am using the eb40A board and debugging using arm-elf-insight.


//---------------------------------------------------------

#   include <cyg/kernel/kapi.h>
#   include <stdio.h>
#   include <stdlib.h>

int main (int agrc, char * argv[])
{
        printf("1.HEllo world..........\n");
        printf("\n2.Hello world again");
        printf("3.Hello world again");

}  //End main

//---------------------------------------------------------

The output is 

//---------------------------------------------------------

  1.HEllo world..........

//---------------------------------------------------------

Why has eCos been implemented such that the '\n' must be included at the end
of the printf statement. Is there a way to avoid this characteristic. Is
there a way to flush the print buffers other than looking for the '\n'. 

Thanks in advance.


Regards,


Sidharth


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Re: [ECOS] Problem with printf

[Nick Garnett]

"Sidharth Jandhyala" <sidharth@clarinox.com> writes:

> Why has eCos been implemented such that the '\n' must be included at the end
> of the printf statement. Is there a way to avoid this characteristic. Is
> there a way to flush the print buffers other than looking for the '\n'. 

This is standard C library behaviour. The library buffers all output
characters internally until either the buffer is full or, for line
buffered streams, a newline is output. If you want to cause buffered
data to be output before either of those conditions occurs, use
fflush(stdout).

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


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Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
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RE: [ECOS] Problem with printf

[Sidharth Jandhyala]

Hi Nick,

 I am still having a problem with the printf. I tried fflush as you
suggested.

//--------------------------------------------------------------------------

#       include <stdio.h>
#       include <stdlib.h>

int main (int agrc, char * argv[])
{
        printf("1.Hello World\n");
        printf("Hello fflush");
        fflush(stdout);

}  //End main

//--------------------------------------------------------------------------


The output I get is 

//--------------------------------------------------------------------------

1. Hello world

//--------------------------------------------------------------------------

I have the latest CVS. Any suggestions??


-------------Sidharth



-----Original Message-----
From: nickg@miso.calivar.com [mailto:nickg@miso.calivar.com] On Behalf Of
Nick Garnett
Sent: Tuesday, 18 May 2004 7:02 PM
To: sidharth@clarinox.com
Cc: ecos-discuss@sources.redhat.com; gokhan@clarinox.com
Subject: Re: [ECOS] Problem with printf

"Sidharth Jandhyala" <sidharth@clarinox.com> writes:

> Why has eCos been implemented such that the '\n' must be included at the
end
> of the printf statement. Is there a way to avoid this characteristic. Is
> there a way to flush the print buffers other than looking for the '\n'. 

This is standard C library behaviour. The library buffers all output
characters internally until either the buffer is full or, for line
buffered streams, a newline is output. If you want to cause buffered
data to be output before either of those conditions occurs, use
fflush(stdout).

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


-- 
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss

Re: [ECOS] Problem with printf

[sandeep]

Sidharth,

have a look at the documentation (man pages on any linux installation will be 
easy enough) of setbuf, setvbuf family of functions, these are present in eCos 
too.you can try
{
setbuf (stdout, NULL);
printf ("Hello World\n");
printf ("Hello fflush");
}

if above also doesn't work, then you need to investigate things deeper down, 
tracing the second printf call

I wonder why fflush(stdout) is not doing the job.

--
regards
sandeep


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RE: [ECOS] Problem with printf

[Gokhan]

Fflush seems like not working for EB40A ( unless we are making a silly
mistake ). Is there any setting that could have missed during the
configuration?

Thanks in advance, 

Gokhan Tanyeri
www.clarinox.com

-----Original Message-----
From: nickg@miso.calivar.com [mailto:nickg@miso.calivar.com] On Behalf
Of Nick Garnett
Sent: Tuesday, May 18, 2004 7:02 PM
To: sidharth@clarinox.com
Cc: ecos-discuss@sources.redhat.com; gokhan@clarinox.com
Subject: Re: [ECOS] Problem with printf


"Sidharth Jandhyala" <sidharth@clarinox.com> writes:

> Why has eCos been implemented such that the '\n' must be included at 
> the end of the printf statement. Is there a way to avoid this 
> characteristic. Is there a way to flush the print buffers other than 
> looking for the '\n'.

This is standard C library behaviour. The library buffers all output
characters internally until either the buffer is full or, for line
buffered streams, a newline is output. If you want to cause buffered
data to be output before either of those conditions occurs, use
fflush(stdout).

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


-- 
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss