/*
|
* Copyright (C) 2009 Philippe Gerum <rpm@xenomai.org>.
|
*
|
* This library is free software; you can redistribute it and/or
|
* modify it under the terms of the GNU Lesser General Public
|
* License as published by the Free Software Foundation; either
|
* version 2 of the License, or (at your option) any later version.
|
*
|
* This library is distributed in the hope that it will be useful,
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
* Lesser General Public License for more details.
|
|
* You should have received a copy of the GNU Lesser General Public
|
* License along with this library; if not, write to the Free Software
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
|
*
|
*
|
* XDDP-based RT/NRT threads communication demo.
|
*
|
* Real-time Xenomai threads and regular Linux threads may want to
|
* exchange data in a way that does not require the former to leave
|
* the real-time domain (i.e. secondary mode). Message pipes - as
|
* implemented by the RTDM-based XDDP protocol - are provided for this
|
* purpose.
|
*
|
* On the Linux domain side, pseudo-device files named /dev/rtp<minor>
|
* give regular POSIX threads access to non real-time communication
|
* endpoints, via the standard character-based I/O interface. On the
|
* Xenomai domain side, sockets may be bound to XDDP ports, which act
|
* as proxies to send and receive data to/from the associated
|
* pseudo-device files. Ports and pseudo-device minor numbers are
|
* paired, meaning that e.g. port 7 will proxy the traffic for
|
* /dev/rtp7. Therefore, port numbers may range from 0 to
|
* CONFIG_XENO_OPT_PIPE_NRDEV - 1.
|
*
|
* All data sent through a bound/connected XDDP socket via sendto(2) or
|
* write(2) will be passed to the peer endpoint in the Linux domain,
|
* and made available for reading via the standard read(2) system
|
* call. Conversely, all data sent using write(2) through the non
|
* real-time endpoint will be conveyed to the real-time socket
|
* endpoint, and made available to the recvfrom(2) or read(2) system
|
* calls.
|
*
|
* In addition to sending datagrams, real-time threads may stream data
|
* in a byte-oriented mode through the proxy as well. This increases
|
* the bandwidth and reduces the overhead, when a lot of data has to
|
* flow down to the Linux domain, if keeping the message boundaries is
|
* not required. The example code below illustrates such use.
|
*
|
* realtime_thread-------------------------------------->----------+
|
* => get socket |
|
* => bind socket to port 0 v
|
* => write scattered traffic to NRT domain via sendto() |
|
* => read traffic from NRT domain via recvfrom() <--|--+
|
* | |
|
* regular_thread--------------------------------------------------+ |
|
* => open /dev/rtp0 | ^
|
* => read traffic from RT domain via read() | |
|
* => echo traffic back to RT domain via write() +--+
|
*/
|
#include <stdio.h>
|
#include <stdlib.h>
|
#include <unistd.h>
|
#include <signal.h>
|
#include <string.h>
|
#include <malloc.h>
|
#include <pthread.h>
|
#include <fcntl.h>
|
#include <errno.h>
|
#include <rtdm/ipc.h>
|
|
pthread_t rt, nrt;
|
|
#define XDDP_PORT 0 /* [0..CONFIG-XENO_OPT_PIPE_NRDEV - 1] */
|
|
static const char *msg[] = {
|
"Surfing With The Alien",
|
"Lords of Karma",
|
"Banana Mango",
|
"Psycho Monkey",
|
"Luminous Flesh Giants",
|
"Moroccan Sunset",
|
"Satch Boogie",
|
"Flying In A Blue Dream",
|
"Ride",
|
"Summer Song",
|
"Speed Of Light",
|
"Crystal Planet",
|
"Raspberry Jam Delta-V",
|
"Champagne?",
|
"Clouds Race Across The Sky",
|
"Engines Of Creation"
|
};
|
|
static void fail(const char *reason)
|
{
|
perror(reason);
|
exit(EXIT_FAILURE);
|
}
|
|
static void *realtime_thread(void *arg)
|
{
|
struct sockaddr_ipc saddr;
|
int ret, s, n = 0, len, b;
|
struct timespec ts;
|
size_t streamsz;
|
char buf[128];
|
|
/*
|
* Get a datagram socket to bind to the RT endpoint. Each
|
* endpoint is represented by a port number within the XDDP
|
* protocol namespace.
|
*/
|
s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_XDDP);
|
if (s < 0) {
|
perror("socket");
|
exit(EXIT_FAILURE);
|
}
|
|
/*
|
* Tell the XDDP driver that we will use the streaming
|
* capabilities on this socket. To this end, we have to
|
* specify the size of the streaming buffer, as a count of
|
* bytes. The real-time output will be buffered up to that
|
* amount, and sent as a single datagram to the NRT endpoint
|
* when fully gathered, or when another source port attempts
|
* to send data to the same endpoint. Passing a null size
|
* would disable streaming.
|
*/
|
streamsz = 1024; /* bytes */
|
ret = setsockopt(s, SOL_XDDP, XDDP_BUFSZ,
|
&streamsz, sizeof(streamsz));
|
if (ret)
|
fail("setsockopt");
|
/*
|
* Bind the socket to the port, to setup a proxy to channel
|
* traffic to/from the Linux domain.
|
*
|
* saddr.sipc_port specifies the port number to use.
|
*/
|
memset(&saddr, 0, sizeof(saddr));
|
saddr.sipc_family = AF_RTIPC;
|
saddr.sipc_port = XDDP_PORT;
|
ret = bind(s, (struct sockaddr *)&saddr, sizeof(saddr));
|
if (ret)
|
fail("bind");
|
|
for (;;) {
|
len = strlen(msg[n]);
|
/*
|
* Send a datagram to the NRT endpoint via the proxy.
|
* The output is artificially scattered in separate
|
* one-byte sendings, to illustrate the use of
|
* MSG_MORE.
|
*/
|
for (b = 0; b < len; b++) {
|
ret = sendto(s, msg[n] + b, 1, MSG_MORE, NULL, 0);
|
if (ret != 1)
|
fail("sendto");
|
}
|
|
printf("%s: sent (scattered) %d-bytes message, \"%.*s\"\n",
|
__FUNCTION__, len, len, msg[n]);
|
|
/* Read back packets echoed by the regular thread */
|
ret = recvfrom(s, buf, sizeof(buf), 0, NULL, 0);
|
if (ret <= 0)
|
fail("recvfrom");
|
|
printf(" => \"%.*s\" echoed by peer\n", ret, buf);
|
|
n = (n + 1) % (sizeof(msg) / sizeof(msg[0]));
|
/*
|
* We run in full real-time mode (i.e. primary mode),
|
* so we have to let the system breathe between two
|
* iterations.
|
*/
|
ts.tv_sec = 0;
|
ts.tv_nsec = 500000000; /* 500 ms */
|
clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL);
|
}
|
|
return NULL;
|
}
|
|
static void *regular_thread(void *arg)
|
{
|
char buf[128], *devname;
|
int fd, ret;
|
|
if (asprintf(&devname, "/dev/rtp%d", XDDP_PORT) < 0)
|
fail("asprintf");
|
|
fd = open(devname, O_RDWR);
|
free(devname);
|
if (fd < 0)
|
fail("open");
|
|
for (;;) {
|
/* Get the next message from realtime_thread. */
|
ret = read(fd, buf, sizeof(buf));
|
if (ret <= 0)
|
fail("read");
|
|
/* Echo the message back to realtime_thread. */
|
ret = write(fd, buf, ret);
|
if (ret <= 0)
|
fail("write");
|
}
|
|
return NULL;
|
}
|
|
int main(int argc, char **argv)
|
{
|
struct sched_param rtparam = { .sched_priority = 42 };
|
pthread_attr_t rtattr, regattr;
|
sigset_t set;
|
int sig;
|
|
sigemptyset(&set);
|
sigaddset(&set, SIGINT);
|
sigaddset(&set, SIGTERM);
|
sigaddset(&set, SIGHUP);
|
pthread_sigmask(SIG_BLOCK, &set, NULL);
|
|
pthread_attr_init(&rtattr);
|
pthread_attr_setdetachstate(&rtattr, PTHREAD_CREATE_JOINABLE);
|
pthread_attr_setinheritsched(&rtattr, PTHREAD_EXPLICIT_SCHED);
|
pthread_attr_setschedpolicy(&rtattr, SCHED_FIFO);
|
pthread_attr_setschedparam(&rtattr, &rtparam);
|
|
errno = pthread_create(&rt, &rtattr, &realtime_thread, NULL);
|
if (errno)
|
fail("pthread_create");
|
|
pthread_attr_init(®attr);
|
pthread_attr_setdetachstate(®attr, PTHREAD_CREATE_JOINABLE);
|
pthread_attr_setinheritsched(®attr, PTHREAD_EXPLICIT_SCHED);
|
pthread_attr_setschedpolicy(®attr, SCHED_OTHER);
|
|
errno = pthread_create(&nrt, ®attr, ®ular_thread, NULL);
|
if (errno)
|
fail("pthread_create");
|
|
__STD(sigwait(&set, &sig));
|
pthread_cancel(rt);
|
pthread_cancel(nrt);
|
pthread_join(rt, NULL);
|
pthread_join(nrt, NULL);
|
|
return 0;
|
}
|
