Filter.h

00001 #ifndef __FILTER_H
00002 #define __FILTER_H
00003 
00004 #include "mbed.h"
00005 #include "math.h"
00006 
00007 class fCircularBuffer {
00008 public:
00009     fCircularBuffer(int length, bool use_median);
00010     float oldest() {if (oldest_index >= 0) return buf[oldest_index]; return 0.0f;}
00011     float newest() {if (newest_index >= 0) return buf[newest_index]; return 0.0f;}
00012     int length() {return _length;}
00013     void add(float x); /*recomputes mean, median - O(length) time*/
00014     float &at(int index);
00015 public:
00016     float &operator[](int index) {return at(index);}
00017 public:
00018     /*O(1) time*/
00019     float mean();
00020     float median();
00021 private:
00022     int _length;
00023     bool _use_median;
00024     int oldest_index, newest_index, num;
00025     float sum;
00026 private:
00027     float *buf;
00028     float *sorted;
00029 };
00030 
00031 class Filter {
00032 public:
00033     virtual float update(float x) = 0;
00034 };
00035 
00036 class MedianFilter : public Filter {
00037 public:
00038     MedianFilter(int length);
00039     virtual float update(float x);
00040 private:
00041     fCircularBuffer *buf;
00042 };
00043 
00044 class MovingAverageFilter : public Filter {
00045 public:
00046     MovingAverageFilter(int length);
00047     virtual float update(float x);
00048 private:
00049     fCircularBuffer *buf;
00050 };
00051 
00052 #endif