kopia lustrzana https://github.com/xaelsouth/rtl-wmbus
77 wiersze
2.2 KiB
C
77 wiersze
2.2 KiB
C
#ifndef MOVING_AVERAGE_FILTER_H
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#define MOVING_AVERAGE_FILTER_H
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/*-
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* Copyright (c) 2017 <xael.south@yandex.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Moving average filter implementation.
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*/
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#include <stdint.h>
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#include <stddef.h>
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typedef struct
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{
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size_t i;
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int *hist;
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const size_t length;
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int sum;
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} MAVGI_FILTER;
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float mavgi(int sample, MAVGI_FILTER *filter);
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float mavgi(int sample, MAVGI_FILTER *filter)
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{
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filter->sum = filter->sum - filter->hist[filter->i] + sample;
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filter->hist[filter->i++] = sample;
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if (filter->i >= filter->length) filter->i = 0;
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return (float)filter->sum / filter->length;
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}
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#if 0
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static int test_mavgi(void)
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{
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#define COEFFS 5
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static int hist[COEFFS];
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static MAVGI_FILTER filter = { .length = COEFFS, .hist = hist };
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#undef COEFFS
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for (int sample = 0; sample < 20; sample++)
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{
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printf("%f, ", mavgi(sample, &filter));
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}
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printf("\n");
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return 0;
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}
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#endif
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#endif /* MOVING_AVERAGE_FILTER_H */
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