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VILLASnode/common/lib/window.c

61 lines
1.6 KiB
C

/** A sliding/moving window.
*
* @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
* @copyright 2014-2019, Institute for Automation of Complex Power Systems, EONERC
* @license GNU General Public License (version 3)
*
* VILLAScommon
*
* 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/>.
*********************************************************************************/
#include <stdlib.h>
#include <villas/window.h>
#include <villas/utils.h>
int window_init(struct window *w, size_t steps, double init)
{
size_t len = LOG2_CEIL(steps);
/* Allocate memory for ciruclar history buffer */
w->data = alloc(len * sizeof(double));
if (!w->data)
return -1;
for (size_t i = 0; i < len; i++)
w->data[i] = init;
w->steps = steps;
w->pos = len;
w->mask = len - 1;
return 0;
}
int window_destroy(struct window *w)
{
free(w->data);
return 0;
}
double window_update(struct window *w, double in)
{
double out = w->data[(w->pos - w->steps) & w->mask];
w->data[w->pos++ & w->mask] = in;
return out;
}