hook: add new moving average hook

lib/hooks/CMakeLists.txt

@@ -34,6 +34,9 @@ set(HOOK_SRC
     jitter_calc.cpp
     limit_rate.cpp
     limit_value.cpp
+    ma.cpp
+    pps_ts.cpp
+    print.cpp
     restart.cpp
     rms.cpp
     scale.cpp
@@ -42,8 +45,6 @@ set(HOOK_SRC
     skip_first.cpp
     stats.cpp
     ts.cpp
-    pps_ts.cpp
-    print.cpp
 )
 
 if(WITH_LUA)

lib/hooks/ma.cpp

@@ -0,0 +1,131 @@
+
+/** Moving average filter.
+ *
+ * @author Steffen Vogel <svogel2@eonerc.rwth-aachen.de>
+ * @copyright 2014-2021, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLASnode
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *********************************************************************************/
+
+/** @addtogroup hooks Hook functions
+ * @{
+ */
+
+#include <villas/hook.hpp>
+#include <villas/sample.h>
+
+namespace villas {
+namespace node {
+
+class MovingAverageHook : public MultiSignalHook {
+
+protected:
+	std::vector<std::vector<double>> smpMemory;
+
+	double accumulator;
+	unsigned windowSize;
+	uint64_t smpMemoryPosition;
+
+public:
+	MovingAverageHook(struct vpath *p, struct vnode *n, int fl, int prio, bool en = true) :
+		MultiSignalHook(p, n, fl, prio, en),
+		smpMemory(),
+		accumulator(0.0),
+		windowSize(0),
+		smpMemoryPosition(0)
+	{ }
+
+	virtual
+	void prepare()
+	{
+		MultiSignalHook::prepare();
+
+		/* Add signals */
+		for (auto index : signalIndices) {
+			auto *origSig = (struct signal *) vlist_at_safe(&signals, index);
+
+			/* Check that signal has float type */
+			if (origSig->type != SignalType::FLOAT)
+				throw RuntimeError("The rms hook can only operate on signals of type float!");
+		}
+
+		/* Initialize sample memory */
+		smpMemory.clear();
+		for (unsigned i = 0; i < signalIndices.size(); i++)
+			smpMemory.emplace_back(windowSize, 0.0);
+
+		state = State::PREPARED;
+	}
+
+	virtual
+	void parse(json_t *json)
+	{
+		int ret;
+		json_error_t err;
+
+		assert(state != State::STARTED);
+
+		MultiSignalHook::parse(json);
+
+		ret = json_unpack_ex(json, &err, 0, "{ s?: i }",
+			"window_size", &windowSize
+		);
+		if (ret)
+			throw ConfigError(json, err, "node-config-hook-rms");
+
+		state = State::PARSED;
+	}
+
+	virtual
+	Hook::Reason process(struct sample *smp)
+	{
+		assert(state == State::STARTED);
+
+		unsigned i = 0;
+		for (auto index : signalIndices) {
+			/* The new value */
+			double newValue = smp->data[index].f;
+
+			/* Append the new value to the history memory */
+			smpMemory[i][smpMemoryPosition % windowSize] = newValue;
+
+			/* Get the old value from the history */
+			double oldValue = smpMemory[i][(smpMemoryPosition + 1) % windowSize];
+
+			/* Update the accumulator */
+			accumulator += newValue;
+			accumulator -= oldValue;
+
+			smp->data[index].f = accumulator / windowSize;
+			i++;
+		}
+
+		smpMemoryPosition++;
+
+		return Reason::OK;
+	}
+};
+
+/* Register hook */
+static char n[] = "ma";
+static char d[] = "A simple moving average filter over a fixed number of past samples";
+static HookPlugin<MovingAverageHook, n, d, (int) Hook::Flags::NODE_READ | (int) Hook::Flags::NODE_WRITE | (int) Hook::Flags::PATH> p;
+
+} /* namespace node */
+} /* namespace villas */
+
+/** @} */