linux 域和xenomai 实时域之间的交互

/*
* 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.
*
* Both threads can use the bi-directional data path to send and
* receive datagrams in a FIFO manner, as illustrated by the simple
* echoing process implemented by this program.
*
* realtime_thread------------------------------>-------+
* => get socket |
* => bind socket to port 0 v
* => write 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() +--+
*
* See Makefile in this directory for build directives.
*
* NOTE: XDDP is a replacement for the legacy RT_PIPE interface
* available from the native skin until Xenomai 3.
*/
#include <sys/mman.h>
#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 <rtdk.h>
#include <rtdm/rtipc.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;
struct timespec ts;
size_t poolsz;
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);
}

/*
* Set a local 16k pool for the RT endpoint. Memory needed to
* convey datagrams will be pulled from this pool, instead of
* Xenomai's system pool.
*/
poolsz = 16384; /* bytes */
ret = setsockopt(s, SOL_XDDP, XDDP_POOLSZ,
&poolsz, sizeof(poolsz));
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
);
/*
* Send a datagram to the NRT endpoint via the proxy.
* We may pass a NULL destination address, since a
* bound socket is assigned a default destination
* address matching the binding address (unless
* connect(2) was issued before bind(2), in which case
* the former would prevail).
*/
ret = sendto(s, msg
, len, 0, NULL, 0);
if (ret != len)
fail("sendto");

rt_printf("%s: sent %d bytes, \"%.*s\"\n",
__FUNCTION__, ret, ret, msg
);

/* Read back packets echoed by the regular thread */
ret = recvfrom(s, buf, sizeof(buf), 0, NULL, 0);
if (ret <= 0)
fail("recvfrom");

rt_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;
}

static void cleanup_upon_sig(int sig)
{
pthread_cancel(rt);
pthread_cancel(nrt);
signal(sig, SIG_DFL);
pthread_join(rt, NULL);
pthread_join(nrt, NULL);
}

int main(int argc, char **argv)
{
struct sched_param rtparam = { .sched_priority = 42 };
pthread_attr_t rtattr, regattr;
sigset_t mask, oldmask;

mlockall(MCL_CURRENT | MCL_FUTURE);

sigemptyset(&mask);
sigaddset(&mask, SIGINT);
signal(SIGINT, cleanup_upon_sig);
sigaddset(&mask, SIGTERM);
signal(SIGTERM, cleanup_upon_sig);
sigaddset(&mask, SIGHUP);
signal(SIGHUP, cleanup_upon_sig);
pthread_sigmask(SIG_BLOCK, &mask, &oldmask);

/*
* This is a real-time compatible printf() package from
* Xenomai's RT Development Kit (RTDK), that does NOT cause
* any transition to secondary (i.e. non real-time) mode when
* writing output.
*/
rt_print_auto_init(1);

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");

sigsuspend(&oldmask);

return 0;
}

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测试结果:

realtime_thread: sent 21 bytes, "Raspberry Jam Delta-V"
=> "Raspberry Jam Delta-V" echoed by peer
realtime_thread: sent 10 bytes, "Champagne?"
=> "Champagne?" echoed by peer
realtime_thread: sent 26 bytes, "Clouds Race Across The Sky"
=> "Clouds Race Across The Sky" echoed by peer
realtime_thread: sent 19 bytes, "Engines Of Creation"
=> "Engines Of Creation" echoed by peer
realtime_thread: sent 22 bytes, "Surfing With The Alien"
=> "Surfing With The Alien" echoed by peer
realtime_thread: sent 14 bytes, "Lords of Karma"
=> "Lords of Karma" echoed by peer
realtime_thread: sent 12 bytes, "Banana Mango"
=> "Banana Mango" echoed by peer
realtime_thread: sent 13 bytes, "Psycho Monkey"
=> "Psycho Monkey" echoed by peer
realtime_thread: sent 21 bytes, "Luminous Flesh Giants"
=> "Luminous Flesh Giants" echoed by peer
realtime_thread: sent 15 bytes, "Moroccan Sunset"
=> "Moroccan Sunset" echoed by peer
realtime_thread: sent 12 bytes, "Satch Boogie"
=> "Satch Boogie" echoed by peer
realtime_thread: sent 22 bytes, "Flying In A Blue Dream"
=> "Flying In A Blue Dream" echoed by peer
realtime_thread: sent 4 bytes, "Ride"
=> "Ride" echoed by peer
realtime_thread: sent 11 bytes, "Summer Song"
=> "Summer Song" echoed by peer
realtime_thread: sent 14 bytes, "Speed Of Light"
=> "Speed Of Light" echoed by peer
realtime_thread: sent 14 bytes, "Crystal Planet"
=> "Crystal Planet" echoed by peer
realtime_thread: sent 21 bytes, "Raspberry Jam Delta-V"
=> "Raspberry Jam Delta-V" echoed by peer
realtime_thread: sent 10 bytes, "Champagne?"
=> "Champagne?" echoed by peer
realtime_thread: sent 26 bytes, "Clouds Race Across The Sky"
=> "Clouds Race Across The Sky" echoed by peer
realtime_thread: sent 19 bytes, "Engines Of Creation"
=> "Engines Of Creation" echoed by peer
realtime_thread: sent 22 bytes, "Surfing With The Alien"
=> "Surfing With The Alien" echoed by peer
realtime_thread: sent 14 bytes, "Lords of Karma"
=> "Lords of Karma" echoed by peer
realtime_thread: sent 12 bytes, "Banana Mango"
=> "Banana Mango" echoed by peer
realtime_thread: sent 13 bytes, "Psycho Monkey"
=> "Psycho Monkey" echoed by peer
realtime_thread: sent 21 bytes, "Luminous Flesh Giants"
=> "Luminous Flesh Giants" echoed by peer
realtime_thread: sent 15 bytes, "Moroccan Sunset"
=> "Moroccan Sunset" echoed by peer
realtime_thread: sent 12 bytes, "Satch Boogie"
=> "Satch Boogie" echoed by peer
realtime_thread: sent 22 bytes, "Flying In A Blue Dream"
=> "Flying In A Blue Dream" echoed by peer
realtime_thread: sent 4 bytes, "Ride"
=> "Ride" echoed by peer
realtime_thread: sent 11 bytes, "Summer Song"
=> "Summer Song" echoed by peer
realtime_thread: sent 14 bytes, "Speed Of Light"
=> "Speed Of Light" echoed by peer
realtime_thread: sent 14 bytes, "Crystal Planet"
=> "Crystal Planet" echoed by peer
realtime_thread: sent 21 bytes, "Raspberry Jam Delta-V"
=> "Raspberry Jam Delta-V" echoed by peer
realtime_thread: sent 10 bytes, "Champagne?"
=> "Champagne?" echoed by peer
realtime_thread: sent 26 bytes, "Clouds Race Across The Sky"
=> "Clouds Race Across The Sky" echoed by peer
realtime_thread: sent 19 bytes, "Engines Of Creation"
=> "Engines Of Creation" echoed by peer
realtime_thread: sent 22 bytes, "Surfing With The Alien"
=> "Surfing With The Alien" echoed by peer