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Diffstat (limited to 'media/libstagefright/wifi-display/TimeSeries.cpp')
-rw-r--r-- | media/libstagefright/wifi-display/TimeSeries.cpp | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/media/libstagefright/wifi-display/TimeSeries.cpp b/media/libstagefright/wifi-display/TimeSeries.cpp new file mode 100644 index 0000000..d882d98 --- /dev/null +++ b/media/libstagefright/wifi-display/TimeSeries.cpp @@ -0,0 +1,67 @@ +/* + * Copyright 2012, 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 "TimeSeries.h" + +#include <math.h> +#include <string.h> + +namespace android { + +TimeSeries::TimeSeries() + : mCount(0), + mSum(0.0) { +} + +void TimeSeries::add(double val) { + if (mCount < kHistorySize) { + mValues[mCount++] = val; + mSum += val; + } else { + mSum -= mValues[0]; + memmove(&mValues[0], &mValues[1], (kHistorySize - 1) * sizeof(double)); + mValues[kHistorySize - 1] = val; + mSum += val; + } +} + +double TimeSeries::mean() const { + if (mCount < 1) { + return 0.0; + } + + return mSum / mCount; +} + +double TimeSeries::sdev() const { + if (mCount < 1) { + return 0.0; + } + + double m = mean(); + + double sum = 0.0; + for (size_t i = 0; i < mCount; ++i) { + double tmp = mValues[i] - m; + tmp *= tmp; + + sum += tmp; + } + + return sqrt(sum / mCount); +} + +} // namespace android |