VILLASnode/lib/hooks/scale.cpp

/** Scale 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 <cstring>

#include <villas/hook.hpp>
#include <villas/sample.h>

namespace villas {
namespace node {

class ScaleHook : public Hook {

protected:
	char *signal_name;
	unsigned signal_index;

	double scale;
	double offset;

public:
	ScaleHook(struct vpath *p, struct vnode *n, int fl, int prio, bool en = true) :
		Hook(p, n, fl, prio, en),
		signal_name(nullptr),
		signal_index(0),
		scale(1),
		offset(0)
	{ }

	virtual void prepare()
	{
		assert(state != State::STARTED);

		if (signal_name) {
			signal_index = vlist_lookup_index<struct signal>(&signals, signal_name);
			if (signal_index < 0)
				throw RuntimeError("Failed to find signal: {}", signal_name);
		}

		state = State::PREPARED;
	}

	virtual ~ScaleHook()
	{
		if (signal_name)
			free(signal_name);
	}

	virtual void parse(json_t *json)
	{
		int ret;
		json_t *json_signal;
		json_error_t err;

		assert(state != State::STARTED);

		Hook::parse(json);

		ret = json_unpack_ex(json, &err, 0, "{ s?: F, s?: F, s: o }",
			"scale", &scale,
			"offset", &offset,
			"signal", &json_signal
		);
		if (ret)
			throw ConfigError(json, err, "node-config-hook-scale");

		switch (json_typeof(json_signal)) {
			case JSON_STRING:
				signal_name = strdup(json_string_value(json_signal));
				break;

			case JSON_INTEGER:
				signal_name = nullptr;
				signal_index = json_integer_value(json_signal);
				break;

			default:
				throw ConfigError(json_signal, "node-config-hook-scale-signal", "Invalid value for setting 'signal'");
		}

		state = State::PARSED;
	}

	virtual Hook::Reason process(struct sample *smp)
	{
		unsigned k = signal_index;

		assert(k < smp->length);
		assert(state == State::STARTED);

		switch (sample_format(smp, k)) {
			case SignalType::INTEGER:
				smp->data[k].i *= scale;
				smp->data[k].i += offset;
				break;

			case SignalType::FLOAT:
				smp->data[k].f *= scale;
				smp->data[k].f += offset;
				break;

			case SignalType::COMPLEX:
				smp->data[k].z *= scale;
				smp->data[k].z += offset;
				break;

			default: { }
		}

		return Reason::OK;
	}
};

/* Register hook */
static char n[] = "scale";
static char d[] = "Scale signals by a factor and add offset";
static HookPlugin<ScaleHook, n, d, (int) Hook::Flags::PATH | (int) Hook::Flags::NODE_READ | (int) Hook::Flags::NODE_WRITE> p;

} /* namespace node */
} /* namespace villas */

/** @} */