Xenomai  3.0.8
xddp-label.c
/*
* 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.
*
* ASCII labels can be attached to bound ports, in order to connect
* sockets to them in a more descriptive way than using plain numeric
* port values.
*
* The example code below illustrates the following process:
*
* realtime_thread1----------------------------->----------+
* => get socket |
* => bind socket to port "xddp-demo |
* => read traffic from NRT domain via recvfrom() <--+--+
* | |
* realtime_thread2----------------------------------------+ |
* => get socket | |
* => connect socket to port "xddp-demo" | |
* => write traffic to NRT domain via sendto() v |
* | ^
* regular_thread------------------------------------------+ |
* => open /proc/xenomai/registry/rtipc/xddp/xddp-demo | |
* => read traffic from RT domain via read() | |
* => mirror traffic 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 rt1, rt2, nrt;
#define XDDP_PORT_LABEL "xddp-demo"
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_thread1(void *arg)
{
struct rtipc_port_label plabel;
struct sockaddr_ipc saddr;
char buf[128];
int ret, s;
/*
* 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);
}
/*
* Set a port label. This name will be registered when
* binding, in addition to the port number (if given).
*/
strcpy(plabel.label, XDDP_PORT_LABEL);
ret = setsockopt(s, SOL_XDDP, XDDP_LABEL,
&plabel, sizeof(plabel));
if (ret)
fail("setsockopt");
/*
* Bind the socket to the port, to setup a proxy to channel
* traffic to/from the Linux domain. Assign that port a label,
* so that peers may use a descriptive information to locate
* it. For instance, the pseudo-device matching our RT
* endpoint will appear as
* /proc/xenomai/registry/rtipc/xddp/<XDDP_PORT_LABEL> in the
* Linux domain, once the socket is bound.
*
* saddr.sipc_port specifies the port number to use. If -1 is
* passed, the XDDP driver will auto-select an idle port.
*/
memset(&saddr, 0, sizeof(saddr));
saddr.sipc_family = AF_RTIPC;
saddr.sipc_port = -1;
ret = bind(s, (struct sockaddr *)&saddr, sizeof(saddr));
if (ret)
fail("bind");
for (;;) {
/* Get packets relayed by the regular thread */
ret = recvfrom(s, buf, sizeof(buf), 0, NULL, 0);
if (ret <= 0)
fail("recvfrom");
printf("%s: \"%.*s\" relayed by peer\n", __FUNCTION__, ret, buf);
}
return NULL;
}
static void *realtime_thread2(void *arg)
{
struct rtipc_port_label plabel;
struct sockaddr_ipc saddr;
int ret, s, n = 0, len;
struct timespec ts;
struct timeval tv;
socklen_t addrlen;
s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_XDDP);
if (s < 0) {
perror("socket");
exit(EXIT_FAILURE);
}
/*
* Set the socket timeout; it will apply when attempting to
* connect to a labeled port, and to recvfrom() calls. The
* following setup tells the XDDP driver to wait for at most
* one second until a socket is bound to a port using the same
* label, or return with a timeout error.
*/
tv.tv_sec = 1;
tv.tv_usec = 0;
ret = setsockopt(s, SOL_SOCKET, SO_RCVTIMEO,
&tv, sizeof(tv));
if (ret)
fail("setsockopt");
/*
* Set a port label. This name will be used to find the peer
* when connecting, instead of the port number.
*/
strcpy(plabel.label, XDDP_PORT_LABEL);
ret = setsockopt(s, SOL_XDDP, XDDP_LABEL,
&plabel, sizeof(plabel));
if (ret)
fail("setsockopt");
memset(&saddr, 0, sizeof(saddr));
saddr.sipc_family = AF_RTIPC;
saddr.sipc_port = -1; /* Tell XDDP to search by label. */
ret = connect(s, (struct sockaddr *)&saddr, sizeof(saddr));
if (ret)
fail("connect");
/*
* We succeeded in making the port our default destination
* address by using its label, but we don't know its actual
* port number yet. Use getpeername() to retrieve it.
*/
addrlen = sizeof(saddr);
ret = getpeername(s, (struct sockaddr *)&saddr, &addrlen);
if (ret || addrlen != sizeof(saddr))
fail("getpeername");
printf("%s: NRT peer is reading from /dev/rtp%d\n",
__FUNCTION__, saddr.sipc_port);
for (;;) {
len = strlen(msg[n]);
/*
* Send a datagram to the NRT endpoint via the proxy.
* We may pass a NULL destination address, since the
* socket was successfully assigned the proper default
* address via connect(2).
*/
ret = sendto(s, msg[n], len, 0, NULL, 0);
if (ret != len)
fail("sendto");
printf("%s: sent %d bytes, \"%.*s\"\n",
__FUNCTION__, ret, ret, msg[n]);
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,
"/proc/xenomai/registry/rtipc/xddp/%s",
XDDP_PORT_LABEL) < 0)
fail("asprintf");
fd = open(devname, O_RDWR);
free(devname);
if (fd < 0)
fail("open");
for (;;) {
/* Get the next message from realtime_thread2. */
ret = read(fd, buf, sizeof(buf));
if (ret <= 0)
fail("read");
/* Relay the message to realtime_thread1. */
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);
/* Both real-time threads have the same attribute set. */
errno = pthread_create(&rt1, &rtattr, &realtime_thread1, NULL);
if (errno)
fail("pthread_create");
errno = pthread_create(&rt2, &rtattr, &realtime_thread2, NULL);
if (errno)
fail("pthread_create");
pthread_attr_init(&regattr);
pthread_attr_setdetachstate(&regattr, PTHREAD_CREATE_JOINABLE);
pthread_attr_setinheritsched(&regattr, PTHREAD_EXPLICIT_SCHED);
pthread_attr_setschedpolicy(&regattr, SCHED_OTHER);
errno = pthread_create(&nrt, &regattr, &regular_thread, NULL);
if (errno)
fail("pthread_create");
sigwait(&set, &sig);
pthread_cancel(rt1);
pthread_cancel(rt2);
pthread_cancel(nrt);
pthread_join(rt1, NULL);
pthread_join(rt2, NULL);
pthread_join(nrt, NULL);
return 0;
}