90 lines
3.1 KiB
C
90 lines
3.1 KiB
C
/***************************************************************************
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* Copyright (C) 2020 - 2025 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN, *
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* Silvano Seva IU2KWO, *
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* Frederik Saraci IU2NRO *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, see <http://www.gnu.org/licenses/> *
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***************************************************************************/
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#ifndef DSP_H
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#define DSP_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* This header contains various DSP utilities which can be used to condition
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* input or output signals when implementing digital modes on OpenRTX.
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*/
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/**
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* Reset the state variables of a DSP object.
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*
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* @param state: state variable.
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*/
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#define dsp_resetState(state) memset(&state, 0x00, sizeof(state))
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/**
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* Data structure holding the internal state of a DC blocking filter.
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*/
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struct dcBlock {
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int32_t accum;
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int32_t prevIn;
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int32_t prevOut;
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};
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/**
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* Run a single step of the DC blocking filter.
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*
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* @param dcb: pointer to DC filter state.
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* @param sample: input sample.
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* @return filtered sample
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*/
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int16_t dsp_dcBlockFilter(struct dcBlock *dcb, int16_t sample);
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/**
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* Remove the DC offset from a collection of samples, processing data in-place.
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*
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* @param state: pointer to the data structure containing the filter state.
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* @param buffer: buffer containing the audio samples.
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* @param length: number of samples contained in the buffer.
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*/
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static inline void dsp_removeDcOffset(struct dcBlock *dcb, int16_t *buffer,
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const size_t length)
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{
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for (size_t i = 0; i < length; i++)
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buffer[i] = dsp_dcBlockFilter(dcb, buffer[i]);
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}
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/*
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* Inverts the phase of the audio buffer passed as paramenter.
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* The buffer will be processed in place to save memory.
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*
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* @param buffer: the buffer to be used as both source and destination.
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* @param length: the length of the input buffer.
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*/
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void dsp_invertPhase(audio_sample_t *buffer, uint16_t length);
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#ifdef __cplusplus
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}
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#endif // __cplusplus
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#endif /* DSP_H */
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