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/*
* Low pass filter
*
* Copyright (c) 2020 Michael Buesch <m@bues.ch>
*
* 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 2 of the License, or
* (at your option) 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "compat.h"
#include "debug.h"
#include "filter.h"
#include "util.h"
#include "arithmetic.h"
uint16_t lp_filter_run(struct lp_filter *lp,
uint8_t shift,
uint16_t in)
{
uint32_t buf;
buf = lp->filter_buf;
if (lp->initialized)
buf = add_sat_u32((buf - (buf >> shift)), in);
else
buf = (uint32_t)in << shift;
lp->filter_buf = buf;
lp->initialized = true;
return lim_u16(buf >> shift);
}
void lp_filter_set(struct lp_filter *lp,
uint8_t shift,
uint16_t in)
{
lp->filter_buf = (uint32_t)in << shift;
lp->initialized = true;
}
void lp_filter_reset(struct lp_filter *lp)
{
lp->filter_buf = 0u;
lp->initialized = false;
}
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