feat: RQF: filter() style interface RunningQuality

pasada-lib/include/ssf_filter.h

@@ -98,8 +98,23 @@ public:
     // note: arg should be an iterator really, but can do later
     /**
      * @param beat individual beat accelero signal
+     * @return true if it is good beat
      */
-    void append(std::vector<double> &rawBeat, std::vector<double> &rawSsf);
+    bool append(std::vector<double> &rawBeat, std::vector<double> &rawSsf);
+};
+
+/**
+ * Signal quality indicator.
+ */
+class RunningQualityFilter {
+protected:
+    RunningQuality f_sqi;
+    std::vector<double> beat_buf;
+    std::vector<double> ssf_buf;
+    double sqi;
+public:
+    RunningQualityFilter(size_t upslope_width);
+    double filter(double y, double ssf, double step);
 };
 
 #endif //PASADASUPERPROJECT_SSF_FILTER_H