First cut at an interface for the read side of an NTP SHM connection.

Not yet used or tested.

1 files changed, 62 insertions, 0 deletions

diff --git a/ntpshm.h b/ntpshm.h
new file mode 100644
index 00000000..f27345d9
--- /dev/null
+++ b/ntpshm.h
@@ -0,0 +1,62 @@
+/*
+ * This file is Copyright (c) 2015 by the GPSD project
+ * BSD terms apply: see the file COPYING in the distribution root for details.
+ */
+
+#ifndef GPSD_NTPSHM_H
+#define GPSD_NTPSHM_H
+
+#include <sys/time.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+
+#define NTPD_BASE	0x4e545030	/* "NTP0" */
+
+/* 
+ * How to read and write fields in an NTP shared segment.
+ * This definition of shmTime is from ntpd source ntpd/refclock_shm.c
+ */
+
+struct shmTime
+{
+    int mode;	/* 0 - if valid set
+		 *       use values,
+		 *       clear valid
+		 * 1 - if valid set
+		 *       if count before and after read of values is equal,
+		 *         use values
+		 *       clear valid
+		 */
+    volatile int count;
+    time_t clockTimeStampSec;
+    int clockTimeStampUSec;
+    time_t receiveTimeStampSec;
+    int receiveTimeStampUSec;
+    int leap;
+    int precision;
+    int nsamples;
+    volatile int valid;
+    unsigned        clockTimeStampNSec;     /* Unsigned ns timestamps */
+    unsigned        receiveTimeStampNSec;   /* Unsigned ns timestamps */
+    int             dummy[8];
+};
+
+#endif
+
+/*
+ * These types are internal to GPSD
+ */
+enum segstat_t {
+    OK, NO_SEGMENT, NOT_READY, BAD_MODE, CLASH};
+
+struct shm_stat_t {
+    struct timespec tvr, tvt;
+    time_t now;
+    int leap;
+};
+
+struct shmTime *shm_get(int, bool);
+extern char *shm_name(const int);
+enum segstat_t shm_query(struct shmTime *, struct shm_stat_t *);
+
+/* end */