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-rw-r--r--src/ipa/rpi/controller/histogram.cpp64
1 files changed, 64 insertions, 0 deletions
diff --git a/src/ipa/rpi/controller/histogram.cpp b/src/ipa/rpi/controller/histogram.cpp
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+++ b/src/ipa/rpi/controller/histogram.cpp
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+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ *
+ * histogram.cpp - histogram calculations
+ */
+#include <math.h>
+#include <stdio.h>
+
+#include "histogram.h"
+
+using namespace RPiController;
+
+uint64_t Histogram::cumulativeFreq(double bin) const
+{
+ if (bin <= 0)
+ return 0;
+ else if (bin >= bins())
+ return total();
+ int b = (int)bin;
+ return cumulative_[b] +
+ (bin - b) * (cumulative_[b + 1] - cumulative_[b]);
+}
+
+double Histogram::quantile(double q, int first, int last) const
+{
+ if (first == -1)
+ first = 0;
+ if (last == -1)
+ last = cumulative_.size() - 2;
+ assert(first <= last);
+ uint64_t items = q * total();
+ while (first < last) /* binary search to find the right bin */
+ {
+ int middle = (first + last) / 2;
+ if (cumulative_[middle + 1] > items)
+ last = middle; /* between first and middle */
+ else
+ first = middle + 1; /* after middle */
+ }
+ assert(items >= cumulative_[first] && items <= cumulative_[last + 1]);
+ double frac = cumulative_[first + 1] == cumulative_[first] ? 0
+ : (double)(items - cumulative_[first]) /
+ (cumulative_[first + 1] - cumulative_[first]);
+ return first + frac;
+}
+
+double Histogram::interQuantileMean(double qLo, double qHi) const
+{
+ assert(qHi > qLo);
+ double pLo = quantile(qLo);
+ double pHi = quantile(qHi, (int)pLo);
+ double sumBinFreq = 0, cumulFreq = 0;
+ for (double pNext = floor(pLo) + 1.0; pNext <= ceil(pHi);
+ pLo = pNext, pNext += 1.0) {
+ int bin = floor(pLo);
+ double freq = (cumulative_[bin + 1] - cumulative_[bin]) *
+ (std::min(pNext, pHi) - pLo);
+ sumBinFreq += bin * freq;
+ cumulFreq += freq;
+ }
+ /* add 0.5 to give an average for bin mid-points */
+ return sumBinFreq / cumulFreq + 0.5;
+}