kopia lustrzana https://github.com/xaelsouth/rtl-wmbus
126 wiersze
3.2 KiB
C
126 wiersze
3.2 KiB
C
#ifndef PPF_H
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#define PPF_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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* Floating and fixed point implementations of Polyphase Filter.
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*/
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#include "fir.h"
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#include <fixedptc/fixedptc.h>
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typedef struct
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{
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float sum;
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size_t phase;
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const size_t max_phase;
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FIRF_FILTER *fir;
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} PPF_FILTER;
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float ppf(float sample, PPF_FILTER *filter);
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float ppf(float sample, PPF_FILTER *filter)
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{
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if (filter->phase == filter->max_phase)
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{
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filter->phase = 0;
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filter->sum = 0;
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}
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filter->sum += firf(sample, filter->fir + filter->phase);
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filter->phase++;
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return filter->sum;
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}
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typedef struct
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{
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fixedpt sum;
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size_t phase;
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const size_t max_phase;
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FIRFP_FILTER *fir;
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} PPFFP_FILTER;
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fixedpt ppffp(fixedpt sample, PPFFP_FILTER *filter);
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fixedpt ppffp(fixedpt sample, PPFFP_FILTER *filter)
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{
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if (filter->phase == filter->max_phase)
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{
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filter->phase = 0;
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filter->sum = 0;
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}
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filter->sum = fixedpt_add(filter->sum, firfp(sample, filter->fir + filter->phase));
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filter->phase++;
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return filter->sum;
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}
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#if 0
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static int test_ppf(void)
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{
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#define PHASES 2
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#define COEFFS 5
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static const float b[PHASES][COEFFS] =
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{
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{0.01208900045, 0.1180545517, 0.2457748215, 0.1180545517, 0.01208900045, },
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{0.04038886734, 0.2065801697, 0.2065801697, 0.04038886734, 0, },
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};
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static float hist[PHASES][COEFFS] = {};
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static FIRF_FILTER fir[PHASES] =
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{
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{.length = COEFFS, .b = b[1], .hist = hist[0]}, // !inverted indexing of fir!
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{.length = COEFFS, .b = b[0], .hist = hist[1]}, // !inverted indexing of fir!
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};
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static PPF_FILTER filter =
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{
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.sum = 0, .phase = 0, .max_phase = PHASES, .fir = fir,
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};
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#undef COEFFS
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#undef PHASES
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for (int sample = 1, phase = 0; sample <= 22; sample++, phase ^= 1)
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{
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float x = ppf(sample, &filter);
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if (phase == 1) printf("%f, ", x);
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}
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return 0;
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}
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#endif
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#endif /* PPF_H */
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