[Piglit] [PATCH 2/2] piglit-util: add piglit_get_microseconds

[Jordan Justen]

v2:
 * Use Chad's cmake detection
 * return value is signed, and a negative indicates an error

Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
Cc: Chad Versace <chad.versace at linux.intel.com>
Cc: Ian Romanick <idr at freedesktop.org>
---
 tests/util/piglit-util.c |   20 ++++++++++++++++++++
 tests/util/piglit-util.h |   10 ++++++++++
 2 files changed, 30 insertions(+)

diff --git a/tests/util/piglit-util.c b/tests/util/piglit-util.c
index 71d55a7..8836978 100644
--- a/tests/util/piglit-util.c
+++ b/tests/util/piglit-util.c
@@ -33,6 +33,10 @@
 #include <string.h>
 #include <errno.h>
 
+#ifdef PIGLIT_HAS_POSIX_CLOCK_MONOTONIC
+#include <time.h>
+#endif
+
 #include "config.h"
 #if defined(HAVE_SYS_TIME_H) && defined(HAVE_SYS_RESOURCE_H) && defined(HAVE_SETRLIMIT)
 #include <sys/time.h>
@@ -462,3 +466,19 @@ write_null:
 	va_end(va);
 	return size_written;
 }
+
+int64_t
+piglit_get_microseconds(void)
+{
+#ifdef PIGLIT_HAS_POSIX_CLOCK_MONOTONIC
+	struct timespec t;
+	int r = clock_gettime(CLOCK_MONOTONIC, &t);
+	if (r >= 0)
+		return (t.tv_sec * 1000000) + (t.tv_nsec / 1000);
+	else
+		return -1LL;
+#else
+	return (int64_t) -1;
+#endif
+}
+
diff --git a/tests/util/piglit-util.h b/tests/util/piglit-util.h
index 52f053e..7bccce8 100644
--- a/tests/util/piglit-util.h
+++ b/tests/util/piglit-util.h
@@ -174,6 +174,16 @@ piglit_source_dir(void);
 size_t
 piglit_join_paths(char buf[], size_t buf_size, int n, ...);
 
+/**
+ * \brief Get a monotonically increasing time in microseconds
+ *
+ * This time can be used for relative time measurements.
+ *
+ * A -1 return value indicates an error.
+ */
+int64_t
+piglit_get_microseconds(void);
+
 #ifdef __cplusplus
 } /* end extern "C" */
 #endif
-- 
1.7.10.4