From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 18 Jul 2007 14:43:22 +0000 (GMT) From: Mathieu JOINIE-MAURIN MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-933887694-1184769802=:73250" Message-ID: <314537.73250.qm@domain.hid> Subject: [Xenomai-help] Problem with rt_pipe and user space communication List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org --0-933887694-1184769802=:73250 Content-Type: text/plain; charset=ascii Hi everybody, I try to learn Xenomai. I have a problem that I do not understand. I want that my real time task to communicate with my user space task through a pipe (FIFO) in order to save sample datas in a file. My problem is the following. I create a pipe with: err = rt_pipe_create(&pipe1,"MyPipe1",1,FIFO_SIZE_PARAM*sizeof(double)); if(err) { printf("pipe MyPipe1 creation failure : %d\n",err); } then in the real time task i write to the pipe like this: err = rt_pipe_stream(&pipe1,&tension0,sizeof(double)); // i already try rt_pipe_write but i got the same result if ( err < 0 ) { printf("rt_pipe_write erreur %d \n",err); } On the user side, i am doing the following : double tabTest[FIFO_SIZE_PARAM]; int nb_read; nb_read=read(pipe1user,tabTest,FIFO_SIZE_PARAM*sizeof(double)); printf("I got %d bytes\n",nb_read); I get a value of 8 for nb_read which corresponds to sizeof(double). But i am expecting more. I do not know why the system function read(2) works like this. Thank you in advance for your help, Mathieu _____________________________________________________________________________ Ne gardez plus qu'une seule adresse mail ! Copiez vos mails vers Yahoo! Mail --0-933887694-1184769802=:73250 Content-Type: text/html; charset=ascii

Hi everybody,

I try to learn Xenomai. I have a problem that I do not understand. I want that my real time task to communicate with my user space task through a pipe (FIFO) in order to save sample datas in a file. My problem is the following. I create a pipe with:

err = rt_pipe_create(&pipe1,"MyPipe1",1,FIFO_SIZE_PARAM*sizeof(double));
    if(err)
    {
        printf("pipe MyPipe1 creation failure : %d\n",err);
    }

then in the real time task i write to the pipe like this:

err = rt_pipe_stream(&pipe1,&tension0,sizeof(double)); // i already try rt_pipe_write but i got the same result
        if ( err < 0 )
        {
        printf("rt_pipe_write erreur %d \n",err);
        }

On the user side, i am doing the following :

    double tabTest[FIFO_SIZE_PARAM];
    int nb_read;
    nb_read=read(pipe1user,tabTest,FIFO_SIZE_PARAM*sizeof(double));
    printf("I got %d bytes\n",nb_read);

I get a value of 8 for nb_read which corresponds to sizeof(double). But i am expecting more. I do not know why the system function read(2) works like this.

Thank you in advance for your help,

Mathieu

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