1 files changed, 71 insertions, 0 deletions
diff --git a/timer/native/com_vladium_utils_timing_HRTimer.c b/timer/native/com_vladium_utils_timing_HRTimer.c
new file mode 100644
index 0000000..647837d
--- /dev/null
+++ b/timer/native/com_vladium_utils_timing_HRTimer.c
@@ -0,0 +1,71 @@
+/* ------------------------------------------------------------------------- */
+/*
+ * A win32 implementation of JNI methods in com.vladium.utils.timing.HRTimer
+ * class. The author compiled it using Microsoft Visual C++ but the code
+ * should be easy to use with any compiler for win32 platform.
+ *
+ * For simplicity, this implementaion assumes JNI 1.2+ and omits error handling.
+ *
+ * (C) 2002, Vladimir Roubtsov [vroubtsov@illinoisalumni.org]
+ */
+/* ------------------------------------------------------------------------- */
+
+#if !defined NDEBUG
+#include <stdio.h>
+#endif // NDEBUG
+
+#include <windows.h>
+
+#include "com_vladium_utils_timing_HRTimer.h"
+
+// scale factor for converting a performancce counter reading into milliseconds:
+static jdouble s_scaleFactor;
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * This method was added in JNI 1.2. It is executed once before any other
+ * methods are called and is ostensibly for negotiating JNI spec versions, but
+ * can also be conveniently used for initializing variables that will not
+ * change throughout the lifetime of this process.
+ */
+JNIEXPORT jint JNICALL
+JNI_OnLoad (JavaVM * vm, void * reserved)
+{
+    LARGE_INTEGER counterFrequency;
+
+    QueryPerformanceFrequency (& counterFrequency);
+
+    // NOTE: counterFrequency will be zero for a machine that does not have
+    // support for a high-resolution counter. This is only likely for very
+    // old hardware but for a robust implementation you should handle this
+    // case.
+
+#if !defined NDEBUG
+    printf ("PCFrequency called: %I64d\n", counterFrequency.QuadPart);
+#endif
+
+    s_scaleFactor = counterFrequency.QuadPart / 1000.0;
+
+
+    return JNI_VERSION_1_2;
+}
+/* ......................................................................... */
+
+/*
+ * Class:     com_vladium_utils_timing_HRTimer
+ * Method:    getTime
+ * Signature: ()D
+ */
+JNIEXPORT jdouble JNICALL
+Java_com_vladium_utils_timing_HRTimer_getTime (JNIEnv * e, jclass cls)
+{
+    LARGE_INTEGER counterReading;
+
+    QueryPerformanceCounter (& counterReading);
+
+    return counterReading.QuadPart / s_scaleFactor;
+}
+
+/* ------------------------------------------------------------------------- */
+/* end of file */