1 files changed, 86 insertions, 0 deletions
diff --git a/src/timing.c b/src/timing.c
new file mode 100644
index 0000000..25cbba7
--- /dev/null
+++ b/src/timing.c
@@ -0,0 +1,86 @@
+/* timing.c -- cross-platform wall time
+ * Copyright (C) 2013  Galois, Inc.  All rights reserved. */
+
+#ifdef HAVE_CONFIG_H
+#	include <config.h>
+#endif
+#define _POSIX_C_SOURCE 199309L
+
+#include <stdint.h>
+
+#include "timing.h"
+#include "require.h"
+
+#define ignore(var) ((void)(var))
+
+const uint64_t MICRO_PER_BASE = 1000000;
+const uint64_t NANO_PER_MICRO = 1000;
+
+// Try to use the POSIX timers, if possible.
+#if HAVE_UNISTD_H
+#	include <unistd.h>
+#endif
+#if (HAVE_UNISTD_H && _POSIX_TIMERS > 0)
+
+#	include <time.h>
+
+#	if __linux__
+		/* Hopefully, you're running linux >=2.6.28, and
+		 * CLOCK_MONOTONIC_RAW exists. */
+		static const clockid_t CLOCK_ID = CLOCK_MONOTONIC_RAW;
+#	elif _POSIX_MONOTONIC_CLOCK
+		// You're not on Linux, but you've got a POSIX monotonic clock.
+		static const clockid_t CLOCK_ID = CLOCK_MONOTONIC;
+#	else
+		// Just use the POSIX wall clock.
+		static const clockid_t CLOCK_ID = CLOCK_REALTIME;
+#	endif
+
+	int timing_get_wall(uint64_t *const result)
+	{
+		int r = 0;
+		struct timespec now;
+		require_zero(clock_gettime(CLOCK_ID, &now), 1);
+		*result = (uint64_t)now.tv_sec * MICRO_PER_BASE
+			+ (uint64_t)now.tv_nsec / NANO_PER_MICRO;
+	done:	return r;
+	}
+
+#elif (__APPLE__ && __MACH__)
+
+	/* No POSIX timers, but we're on a Mac, so we can use
+	 * 'mach_absolute_time'. */
+#	include <mach/mach_time.h>
+
+	int timing_get_wall(uint64_t *const result)
+	{
+		static mach_timebase_info_data_t timebase_info;
+		int r = 0;
+		*result = mach_absolute_time();
+		/* *result is now in units of Mach ticks.  Convert that to
+                 * nanoseconds using the timebase information that Mach
+                 * provides.  Note that 'timebase_info' is static, so it got
+                 * zeroed out at the start of the program run; if its
+                 * denominator is still zero, we've definitely not stored
+                 * anything in it yet. */
+		if (timebase_info.denom == 0) {
+			require_zero(mach_timebase_info(&timebase_info), 1);
+		}
+		*result = *result * timebase_info.numer / timebase_info.denom;
+		// Convert nanoseconds to microseconds.
+		*result /= NANO_PER_MICRO;
+	done:	return r;
+	}
+
+#else
+
+	// I have no clue what wacky platform you're on.
+#	error Unsupported timing platform
+
+	int timing_get_wall(uint64_t *const result)
+	{
+		ignore(result);
+		return -1;
+	}
+
+#endif