On 24/03/07, Philippe Gerum <[EMAIL PROTECTED]> wrote:
[...]
I would add that if you really want to keep the pipe semantics for
exchanging data without crossing domains between real-time tasks, then
you may access the real-time API of message pipes from user-space too.
i.e.
rt_pipe_create/bind/delete/read/write/stream() are all available from a
user-space application, in which case data exchange will happen in
primary mode.
rt_pipe_read -> rt_pipe_receive -> xnpipe_recv -> take from state->inq
rt_pipe_write -> rt_pipe_send -> xnpipe_send -> put into state->outq
So there are 2 different queues.
If a user space side makes use of rt_pipe_read(), then a kernel side
(driver) should use
xnpipe_write(), not rt_pipe_*
For data transfer in the opposite direction, [user space] rt_pipe_write()
---> [kernel space] xnpipe_read()
kernel-side:
void foo_task(void)
{
for (;;) {
rt_pipe_read/write(&pipe_desc, ...);
}
}
int init_module(void)
{
rt_pipe_create(&pipe_desc, "channel", ...);
}
user-space side:
int main(int argc, char *argv[])
{
#ifdef REALTIME_TO_REALTIME
/* promote main() to the Xenomai real-time space */
rt_task_shadow(&task_desc, __FUNCTION__, ...);
/* bind to the pipe created in kernel space */
rt_pipe_bind(&pipe_desc, "channel", TM_INFINITE);
for (;;) {
rt_pipe_read/write(&pipe_desc, "channel", ...);
}
#else /* REALTIME_TO_REGULAR */
fd = open("/proc/xenomai/registry/native/pipes/channel",O_RDWR);
for (;;) {
read/write(fd, ...);
}
#endif
}
--
Philippe.
--
Best regards,
Dmitry Adamushko
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