From e2fa7956b87c23a8229926f39a3863ecd4d4752a Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Fri, 18 Sep 2009 19:47:51 +0000
Subject: Add timespec helper routines.

---
 src/timespec.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 src/timespec.c

(limited to 'src/timespec.c')

diff --git a/src/timespec.c b/src/timespec.c
new file mode 100644
index 0000000..f8ab791
--- /dev/null
+++ b/src/timespec.c
@@ -0,0 +1,109 @@
+/*************************************************************************
+ * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com>               *
+ *                                                                       *
+ * This file is part of The Sandglass Library.                           *
+ *                                                                       *
+ * The Sandglass 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  *
+ * 3 of the License, or (at your option) any later version.              *
+ *                                                                       *
+ * The Sandglass 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 program.  If not, see                         *
+ * <http://www.gnu.org/licenses/>.                                       *
+ *************************************************************************/
+
+#include "sandglass_impl.h"
+#include "sandglass.h"
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+void
+sandglass_get_currtime(struct timespec *ts)
+{
+  static int monotonic = 0;
+  if (!monotonic) {
+    monotonic = sysconf(_SC_MONOTONIC_CLOCK);
+  }
+
+  if (monotonic > 0) {
+    if (clock_gettime(CLOCK_MONOTONIC, ts) != 0) {
+      fprintf(stderr,
+              "libsandglass: couldn't get value of clock CLOCK_MONOTONIC\n");
+      exit(EXIT_FAILURE);
+    }
+  } else {
+    if (clock_gettime(CLOCK_REALTIME, ts) != 0) {
+      fprintf(stderr,
+              "libsandglass: couldn't get value of clock CLOCK_REALTIME\n");
+      exit(EXIT_FAILURE);
+    }
+  }
+}
+
+void
+sandglass_timespec_add(struct timespec *ts, const struct timespec *d)
+{
+  if (d->tv_nsec >= 1000000000L - ts->tv_nsec) {
+    ts->tv_nsec += d->tv_nsec - 1000000000L;
+    ++ts->tv_sec;
+  } else {
+    ts->tv_nsec += d->tv_nsec;
+  }
+  ts->tv_sec += d->tv_sec;
+}
+
+void
+sandglass_timespec_sub(struct timespec *ts, const struct timespec *d)
+{
+  if (d->tv_nsec > ts->tv_nsec) {
+    ts->tv_nsec -= d->tv_nsec - 1000000000L;
+    --ts->tv_sec;
+  } else {
+    ts->tv_nsec -= d->tv_nsec;
+  }
+  ts->tv_sec -= d->tv_sec;
+}
+
+int
+sandglass_timespec_cmp(const struct timespec *a, const struct timespec *b)
+{
+  if (a->tv_sec > b->tv_sec)
+    return 1;
+  else if (a->tv_sec == b->tv_sec) {
+    if (a->tv_nsec > b->tv_nsec)
+      return 1;
+    else if (a->tv_nsec == b->tv_nsec)
+      return 0;
+    else
+      return -1;
+  }
+  else
+    return -1;
+}
+
+/* Spins for the time interval specified by ts */
+void
+sandglass_spin(struct timespec *ts)
+{
+  struct timespec curr, until;
+  sandglass_get_currtime(&curr);
+  until = curr;
+  sandglass_timespec_add(&until, ts);
+
+  /* Spin */
+  do {
+    sandglass_get_currtime(&curr);
+  } while (sandglass_timespec_cmp(&curr, &until) < 0);
+
+  /* Adjust ts to the time actually waited */
+  sandglass_timespec_sub(&curr, &until);
+  sandglass_timespec_add(ts, &curr);
+}
-- 
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