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/*
* Xytronic LF-1600
* Low pass filter
*
* Copyright (c) 2015 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 "filter.h"
uint16_t lp_filter_u16_run(struct lp_filter_u16 *lp, uint16_t in,
uint8_t filter_shift)
{
uint24_t buf, out;
buf = lp->filter_buf;
buf -= buf >> filter_shift;
buf += in;
lp->filter_buf = buf;
out = buf >> filter_shift;
return (uint16_t)min(out, (uint24_t)UINT16_MAX);
}
fixpt_t lp_filter_fixpt_run(struct lp_filter_fixpt *lp, fixpt_t in,
fixpt_t div)
{
fixpt_t buf, out;
buf = lp->filter_buf;
buf = fixpt_sub(buf, fixpt_div(buf, div));
buf = fixpt_add(buf, in);
lp->filter_buf = buf;
out = fixpt_div(buf, div);
return out;
}
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