mv libcpustats from frameworks/native to frameworks/av
OK to lose history
Change-Id: Ieca78edc5dfe479dd7ea48fe7e0f3c164356cee3
diff --git a/media/libcpustats/CentralTendencyStatistics.cpp b/media/libcpustats/CentralTendencyStatistics.cpp
new file mode 100644
index 0000000..42ab62b
--- /dev/null
+++ b/media/libcpustats/CentralTendencyStatistics.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+
+#include <cpustats/CentralTendencyStatistics.h>
+
+void CentralTendencyStatistics::sample(double x)
+{
+ // update min and max
+ if (x < mMinimum)
+ mMinimum = x;
+ if (x > mMaximum)
+ mMaximum = x;
+ // Knuth
+ if (mN == 0) {
+ mMean = 0;
+ }
+ ++mN;
+ double delta = x - mMean;
+ mMean += delta / mN;
+ mM2 += delta * (x - mMean);
+}
+
+void CentralTendencyStatistics::reset()
+{
+ mMean = NAN;
+ mMedian = NAN;
+ mMinimum = INFINITY;
+ mMaximum = -INFINITY;
+ mN = 0;
+ mM2 = 0;
+ mVariance = NAN;
+ mVarianceKnownForN = 0;
+ mStddev = NAN;
+ mStddevKnownForN = 0;
+}
+
+double CentralTendencyStatistics::variance() const
+{
+ double variance;
+ if (mVarianceKnownForN != mN) {
+ if (mN > 1) {
+ // double variance_n = M2/n;
+ variance = mM2 / (mN - 1);
+ } else {
+ variance = NAN;
+ }
+ mVariance = variance;
+ mVarianceKnownForN = mN;
+ } else {
+ variance = mVariance;
+ }
+ return variance;
+}
+
+double CentralTendencyStatistics::stddev() const
+{
+ double stddev;
+ if (mStddevKnownForN != mN) {
+ stddev = sqrt(variance());
+ mStddev = stddev;
+ mStddevKnownForN = mN;
+ } else {
+ stddev = mStddev;
+ }
+ return stddev;
+}