From a5ea1eb0270b4902d04a783484a6b2c704553bc6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Xose=20P=C3=A9rez?= <xose.perez@gmail.com>
Date: Thu, 21 Dec 2017 17:09:38 +0100
Subject: [PATCH] Refactor filters

---
 code/espurna/filters/BaseFilter.h          |  2 +-
 code/espurna/filters/MaxFilter.h           |  2 +-
 code/espurna/filters/MedianFilter.h        | 14 +++++--
 code/espurna/filters/MovingAverageFilter.h | 44 +++++++++++++++-------
 4 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/code/espurna/filters/BaseFilter.h b/code/espurna/filters/BaseFilter.h
index bef36c65..fb422c32 100644
--- a/code/espurna/filters/BaseFilter.h
+++ b/code/espurna/filters/BaseFilter.h
@@ -32,7 +32,7 @@ class BaseFilter {
         virtual double max() {
             double max = 0;
             for (unsigned char i = 1; i < _data.size(); i++) {
-                if (max < _data.at(i)) max = _data.at(i);
+                if (max < _data[i]) max = _data[i];
             }
             return max;
         }
diff --git a/code/espurna/filters/MaxFilter.h b/code/espurna/filters/MaxFilter.h
index 58f6ec69..683e58f6 100644
--- a/code/espurna/filters/MaxFilter.h
+++ b/code/espurna/filters/MaxFilter.h
@@ -12,7 +12,7 @@ class MaxFilter : public BaseFilter {
 
     public:
 
-        virtual double result() {
+        double result() {
             return max();
         }
 
diff --git a/code/espurna/filters/MedianFilter.h b/code/espurna/filters/MedianFilter.h
index 005788fd..531252a4 100644
--- a/code/espurna/filters/MedianFilter.h
+++ b/code/espurna/filters/MedianFilter.h
@@ -12,9 +12,13 @@ class MedianFilter : public BaseFilter {
     public:
 
         virtual void reset() {
+
+            // When resetting we get the last value
+            // and make it the first of the new series
             double last = _data.empty() ? 0 : _data.back();
             _data.clear();
             add(last);
+
         }
 
         virtual double result() {
@@ -25,9 +29,13 @@ class MedianFilter : public BaseFilter {
 
                 for (unsigned char i = 1; i <= _data.size() - 2; i++) {
 
-                    double previous = _data.at(i-1);
-                    double current = _data.at(i);
-                    double next = _data.at(i+1);
+                    // For each position,
+                    // we find the median with the previous and next value
+                    // and use that for the sum
+
+                    double previous = _data[i-1];
+                    double current = _data[i];
+                    double next = _data[i+1];
 
                     if (previous > current) std::swap(previous, current);
                     if (current > next) std::swap(current, next);
diff --git a/code/espurna/filters/MovingAverageFilter.h b/code/espurna/filters/MovingAverageFilter.h
index 7855ff22..0c48eff9 100644
--- a/code/espurna/filters/MovingAverageFilter.h
+++ b/code/espurna/filters/MovingAverageFilter.h
@@ -12,30 +12,48 @@ class MovingAverageFilter : public BaseFilter {
 
     public:
 
-        MovingAverageFilter(unsigned char size) {
-            _size = size;
-            for (unsigned char i=0; i<size; i++) {
-                _data.push_back(0);
+        void add(double value) {
+
+            // If we are at the end of the vector we add a new element
+            if (_pointer >= _data.size()) {
+                _sum = _sum + value;
+                _data.push_back(value);
+
+            // Else we substract the old value at the current poisiton and overwrite it
+            } else {
+                _sum = _sum + value - _data[_pointer];
+                _data[_pointer] = value;
             }
-        }
 
-        virtual void add(double value) {
-            _sum = _sum + value - _data.at(_pointer);
-            _data.at(_pointer) = value;
-            _pointer = (_pointer + 1) % _size;
+            _pointer++;
+            
         }
 
-        virtual void reset() {
-            // Nothing to do
+        void reset() {
+
+            // I assume series length to be the number of data points since last reset,
+            // so I zero-ed old data points from this point on
+            for (unsigned char i=_pointer; i<_data.size(); i++) {
+                _data[i] = 0;
+            }
+
+            _pointer = 0;
+
         }
 
-        virtual double result() {
+        double result() {
+
+            // At this point we want to return the sum since last request
+            for (unsigned char i=_pointer; i<_data.size(); i++) {
+                _sum = _sum - _data[i];
+            }
+
             return _sum;
+
         }
 
     protected:
 
-        unsigned char _size = 0;
         unsigned char _pointer = 0;
         double _sum = 0;