[LinuxPPS] PPS next steps...

[George Spelvin]

Just an addendum, I tested the poll() function, and it seems to work.
My ppstest.c changes follow.

--- ppstest.c	2009-02-03 09:05:56.000000000 -0500
+++ ppstest2.c	2009-02-06 16:54:44.000000000 -0500
@@ -4,6 +4,7 @@
 #include <fcntl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <poll.h>
 
 #include <timepps.h>
 
@@ -15,7 +16,7 @@
 	printf("trying PPS source \"%s\"\n", path);
 
 	/* Try to find the source by using the supplied "path" name */
-	ret = open(path, O_RDWR);
+	ret = open(path, O_RDONLY);
 	if (ret < 0) {
 		fprintf(stderr, "unable to open device \"%s\" (%m)\n", path);
 		return ret;
@@ -64,25 +65,45 @@
 	return 0;
 }
 
+#define TIMEOUT 3	/* Seconds */
 int fetch_source(int i, pps_handle_t *handle, int *avail_mode)
 {
 	struct timespec timeout;
 	pps_info_t infobuf;
 	int ret;
+#if 1
+	struct pollfd pfd = { *handle, POLLIN, 0 };
+
+retry:
+	ret = poll(&pfd, 1, TIMEOUT * 1000);
+	if (ret < 0) {
+		if (errno == EINTR) {
+			fprintf(stderr, "time_pps_fetch() got a signal!\n");
+			goto retry;
+		}
+		perror("time_pps_fetch poll():");
+		return ret;
+	}
+	if (ret == 0) {
+		fprintf(stderr, "time_pps_fetch poll timeout:");
+		return -1;
+	}
+	/* Okay, ready to read */
+	fprintf(stderr, "time_pps_fetch poll success %d\n", ret);
 
 	/* create a zero-valued timeout */
-	timeout.tv_sec = 3;
+	timeout.tv_sec = 0;
+	timeout.tv_nsec = 0;
+#else
+
+	timeout.tv_sec = TIMEOUT;
 	timeout.tv_nsec = 0;
 
 retry:
-	if (*avail_mode & PPS_CANWAIT) /* waits for the next event */
-		ret = time_pps_fetch(*handle, PPS_TSFMT_TSPEC, &infobuf,
-				   &timeout);
-	else {
+	if (!(*avail_mode & PPS_CANWAIT)) /* waits for the next event */
 		sleep(1);
-		ret = time_pps_fetch(*handle, PPS_TSFMT_TSPEC, &infobuf,
-				   &timeout);
-	}
+#endif
+	ret = time_pps_fetch(*handle, PPS_TSFMT_TSPEC, &infobuf, &timeout);
 	if (ret < 0) {
 		if (ret == -EINTR) {
 			fprintf(stderr, "time_pps_fetch() got a signal!\n");
@@ -93,9 +114,7 @@
 		return -1;
 	}
 
-	printf("source %d - "
-	       "assert %ld.%09ld, sequence: %ld - "
-	       "clear  %ld.%09ld, sequence: %ld\n",
+	printf("source %d - assert %ld.%09ld #%ld - clear  %ld.%09ld #%ld\n",
 	       i,
 	       infobuf.assert_timestamp.tv_sec,
 	       infobuf.assert_timestamp.tv_nsec,
@@ -117,7 +136,7 @@
 	int num;
 	pps_handle_t handle[4];
 	int avail_mode[4];
-	int i = 0;
+	int i;
 	int ret;
 
 	/* Check the command line */