add a new hook to limit the value range

lib/hooks/CMakeLists.txt

@@ -32,6 +32,7 @@ set(HOOK_SRC
     gate.cpp
     jitter_calc.cpp
     limit_rate.cpp
+    limit_value.cpp
     restart.cpp
     scale.cpp
     shift_seq.cpp

lib/hooks/limit_value.cpp

@@ -0,0 +1,184 @@
+/** Limit hook.
+ *
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2014-2020, 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 <bitset>
+
+#include <cstring>
+
+#include <villas/hook.hpp>
+#include <villas/node/exceptions.hpp>
+#include <villas/signal.h>
+#include <villas/sample.h>
+
+namespace villas {
+namespace node {
+
+class LimitValueHook : public Hook {
+
+protected:
+	unsigned offset;
+
+	float min, max;
+
+	std::bitset<MAX_SAMPLE_LENGTH> mask;
+	vlist signal_names;
+
+public:
+	LimitValueHook(struct vpath *p, struct node *n, int fl, int prio, bool en = true) :
+		Hook(p, n, fl, prio, en)
+	{
+		int ret;
+
+		ret = vlist_init(&signal_names);
+		if (ret)
+			throw RuntimeError("Failed to intialize list");
+
+		state = State::INITIALIZED;
+	}
+
+	virtual ~LimitValueHook()
+	{
+		vlist_destroy(&signal_names, nullptr, true);
+	}
+
+	virtual void prepare()
+	{
+		int ret;
+		struct signal *avg_sig;
+
+		assert(state == State::CHECKED);
+
+		/* Setup mask */
+		for (size_t i = 0; i < vlist_length(&signal_names); i++) {
+			char *signal_name = (char *) vlist_at_safe(&signal_names, i);
+
+			int index = vlist_lookup_index(&signals, signal_name);
+			if (index < 0)
+				throw RuntimeError("Failed to find signal {}", signal_name);
+
+			mask.set(index);
+		}
+
+		if (mask.none())
+			throw RuntimeError("Invalid signal mask");
+
+		/* Add averaged signal */
+		avg_sig = signal_create("average", nullptr, SignalType::FLOAT);
+		if (!avg_sig)
+			throw RuntimeError("Failed to create new signal");
+
+		ret = vlist_insert(&signals, offset, avg_sig);
+		if (ret)
+			throw RuntimeError("Failed to intialize list");
+
+		state = State::PREPARED;
+	}
+
+	virtual void parse(json_t *cfg)
+	{
+		int ret;
+		size_t i;
+		json_error_t err;
+		json_t *json_signals, *json_signal;
+
+		assert(state != State::STARTED);
+
+		Hook::parse(cfg);
+
+		ret = json_unpack_ex(cfg, &err, 0, "{ s: f, s: f, s: o }",
+			"min", &min,
+			"min", &max,
+			"signals", &json_signals
+		);
+		if (ret)
+			throw ConfigError(cfg, err, "node-config-hook-average");
+
+		if (!json_is_array(json_signals))
+			throw ConfigError(json_signals, "node-config-hook-average-signals", "Setting 'signals' must be a list of signal names");
+
+		json_array_foreach(json_signals, i, json_signal) {
+			switch (json_typeof(json_signal)) {
+				case JSON_STRING:
+					vlist_push(&signal_names, strdup(json_string_value(json_signal)));
+					break;
+
+				case JSON_INTEGER:
+					mask.set(json_integer_value(json_signal));
+					break;
+
+				default:
+					throw ConfigError(json_signal, "node-config-hook-average-signals", "Invalid value for setting 'signals'");
+			}
+		}
+
+		state = State::PARSED;
+	}
+
+	virtual Hook::Reason process(sample *smp)
+	{
+		assert(state == State::STARTED);
+
+		for (unsigned k = 0; k < smp->length; k++) {
+			if (!mask.test(k))
+				continue;
+
+			switch (sample_format(smp, k)) {
+				case SignalType::INTEGER:
+					if (smp->data[k].i > max)
+						smp->data[k].i = max;
+
+					if (smp->data[k].i < min)
+						smp->data[k].i = min;
+					break;
+
+				case SignalType::FLOAT:
+					if (smp->data[k].f > max)
+						smp->data[k].f = max;
+
+					if (smp->data[k].f < min)
+						smp->data[k].f = min;
+					break;
+
+				case SignalType::INVALID:
+				case SignalType::COMPLEX:
+				case SignalType::BOOLEAN:
+					return Hook::Reason::ERROR; /* not supported */
+			}
+		}
+
+		return Reason::OK;
+	}
+};
+
+/* Register hook */
+static char n[] = "average";
+static char d[] = "Calculate average over some signals";
+static HookPlugin<LimitValueHook, n , d, (int) Hook::Flags::PATH | (int) Hook::Flags::NODE_READ | (int) Hook::Flags::NODE_WRITE> p;
+
+} /* namespace node */
+} /* namespace villas */
+
+/** @} */