Add contrib/ppscheck utility to test for 1PPS without a lot of code complexity.

2 files changed, 69 insertions, 0 deletions

diff --git a/contrib/README b/contrib/README
index 71dc8412..133c3875 100644
--- a/contrib/README
+++ b/contrib/README
@@ -45,3 +45,10 @@ to create a snapshot of the current sat view.
 ntpoffset generate an estimate of your GPS's offset from a peerstats
 file.  For instructions on how to use this script, see the GPSD Time
 Service HOWTO in this distrubution.
+
+ppscheck watches a specified serial device for changes in handshake lines
+CD, RI, and CTS by running ioctl(...., TIOCMIWAIT, ...) in a loop.  When it
+sees a state change it emits a timestamped line of output dumping the state
+of the handshake signals. It's useful for checking whether a device is
+emitting 1PPS.
+  
diff --git a/contrib/ppscheck.c b/contrib/ppscheck.c
new file mode 100644
index 00000000..6371639c
--- /dev/null
+++ b/contrib/ppscheck.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#ifndef S_SPLINT_S
+#include <unistd.h>
+#endif /* S_SPLINT_S */
+#include <fcntl.h>	/* needed for open() and friends */
+#include <sys/ioctl.h>
+#include <errno.h>
+#include <time.h>
+
+struct assoc {
+    int mask;
+    char *string;
+};
+
+const static struct assoc hlines[] = {
+    {TIOCM_CD, "TIOCM_CD"},
+    {TIOCM_RI, "TIOCM_RI"},
+    {TIOCM_CTS, "TIOCM_CTS"},
+};
+
+
+int main(int argc, char *argv[])
+{
+    struct timespec ts;
+    int fd = open(argv[1], O_RDONLY);
+
+    if (fd == -1) {
+	(void)fprintf(stderr,
+		      "open(%s) failed: %d %.40s\n",
+		      argv[1], errno, strerror(errno));
+	return 1;
+    }
+
+    (void)printf("Beginning wait...\n");
+
+    for (;;) {
+	if (ioctl(fd, TIOCMIWAIT, TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS) != 0) {
+	    (void)fprintf(stderr,
+			  "PPS ioctl(TIOCMIWAIT) failed: %d %.40s\n",
+			  errno, strerror(errno));
+	    break;
+	} else {
+	    const struct assoc *sp;
+	    int handshakes;
+
+	    clock_gettime(CLOCK_REALTIME, &ts);
+	    ioctl(fd, TIOCMGET, &handshakes);
+	    (void)fprintf(stdout, "%10ld %10ld", ts.tv_sec, ts.tv_nsec);
+	    for (sp = hlines;
+		 sp < hlines + sizeof(hlines)/sizeof(hlines[0]);
+		 sp++)
+		if ((handshakes & sp->mask) != 0) {
+		    (void)fputc(' ', stdout);
+		    (void)fputs(sp->string, stdout);
+		}
+	    (void)fputc('\n', stdout);
+	}
+    } 
+}