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<HTML
><HEAD
><TITLE
>rtf_create_handler</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"></HEAD
><BODY
CLASS="REFENTRY"
><H1
><A
NAME="AEN1"
>rtf_create_handler</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN5"
></A
><H2
>Name</H2
>rtf_create_handler -- install a handler for realtime fifo data</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8"
></A
><H2
>Synopsis</H2
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SYNOPSIS"
> #include <rtl_fifo.h>
int <TT
CLASS="FUNCTION"
>rtf_create_handler</TT
>(unsigned int <TT
CLASS="PARAMETER"
><I
>fifo</I
></TT
>, int (* <TT
CLASS="PARAMETER"
><I
>handler</I
></TT
>)());</PRE
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN13"
></A
><H2
>DESCRIPTION</H2
><P
><TT
CLASS="FUNCTION"
>rtf_create_handler</TT
> installs a handler which is executed when data is written to or read from a real-time fifo (RT-FIFO) by a user-space process. <TT
CLASS="PARAMETER"
><I
>fifo</I
></TT
> is an RT-FIFO that must have previously been created with a call to <TT
CLASS="FUNCTION"
>rtf_create</TT
>. <TT
CLASS="PARAMETER"
><I
>handler</I
></TT
> is then called whenever a Linux process accesses that fifo. The handler is executed with the Linux (i.e., lowest) priority.</P
><P
><TT
CLASS="FUNCTION"
>rtf_create_handler</TT
> is often used in conjunction with rtf_get to process data acquired asynchronously from a Linux process. The installed handler calls <TT
CLASS="FUNCTION"
>rtf_get</TT
> when data is present. Because the handler is only executed when there is activity on the fifo, polling is not necessary.</P
><P
>The RT-FIFO is a mechanism, implemented as a character device, to communicate between realtime software components (either in threads or handlers),
and between realtime software and ordinary Linux processes. The rtf_* functions are used in RT mode; Linux processes use standard character device access functions such as <TT
CLASS="FUNCTION"
>read(2)</TT
>, <TT
CLASS="FUNCTION"
>write(2)</TT
> and <TT
CLASS="FUNCTION"
>select(2)</TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN27"
></A
><H2
>RETURN VALUE</H2
><P
>On success, 0 is returned. On failure, a negative value is returned as described below.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN30"
></A
><H2
>NOTES</H2
><P
> The handler is only called when a Linux process accesses the FIFO. To install a handler that would be called on <TT
CLASS="FUNCTION"
>rtf_put</TT
> or <TT
CLASS="FUNCTION"
>rtf_get</TT
>, use <TT
CLASS="FUNCTION"
>rtf_create_rt_handler</TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN36"
></A
><H2
>ERRORS</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>-EINVAL</DT
><DD
><P
><TT
CLASS="PARAMETER"
><I
>fifo</I
></TT
> is greater than or equal to RTF_NO, or is not a valid RT-FIFO identifier; or <TT
CLASS="PARAMETER"
><I
>handler</I
></TT
> is NULL.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN45"
></A
><H2
>SEE ALSO</H2
><A
HREF="rtf_create.3.html"
TARGET="_top"
>rtf_create(3)</A
>, <A
HREF="rtf_create_rt_handler.3.html"
TARGET="_top"
>rtf_create_rt_handler(3)</A
>, <A
HREF="rtf_destroy.3.html"
TARGET="_top"
>rtf_destroy(3)</A
>, <A
HREF="rtf_get.3.html"
TARGET="_top"
>rtf_get(3)</A
>, <A
HREF="rtf_put.3.html"
TARGET="_top"
>rtf_put(3)</A
><P
>1997 Jerry Epplin.</P
><P
>Modifications for RTLinux 2.x and 3.x by Michael Barabanov. 2001 FSMLabs Inc.</P
><P
>All rights reserved.</P
></DIV
></BODY
></HTML
>
|
