rtbuf/rtbuf/rtbuf_signal_lowpass.c

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• Hash : 19b6f98d
  Author : Thomas de Grivel
  Date : 2020-02-03T21:29:37
  

  update copyright
  

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• rtbuf_signal_lowpass.c

• /*
   * Copyright 2020 Thomas de Grivel <thoxdg@gmail.com> +33614550127
   * Copyright 2020 Judy Najnudel
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <math.h>
  #include "rtbuf.h"
  #include "rtbuf_signal.h"
  
  int rtbuf_signal_lowpass_start (s_rtbuf *rtb)
  {
    s_rtbuf_signal_lowpass_data *data;
    assert(rtb->proc->out_bytes == sizeof(*data));
    data = (s_rtbuf_signal_lowpass_data*) rtb->data;
    data->x1 = 0;
    data->y1 = 0;
    return 0;
  }
  
  int rtbuf_signal_lowpass (s_rtbuf *rtb)
  {
    s_rtbuf_signal_fun in;
    s_rtbuf_signal_fun cutoff;
    s_rtbuf_signal_lowpass_data *data;
    unsigned int i = 0;
    rtbuf_signal_fun(rtb, RTBUF_SIGNAL_LOWPASS_IN_SIGNAL, &in);
    rtbuf_signal_fun(rtb, RTBUF_SIGNAL_LOWPASS_IN_CUTOFF, &cutoff);
    data = (s_rtbuf_signal_lowpass_data*) rtb->data;
    while (i < RTBUF_SIGNAL_SAMPLES) {
      double x = in.sample_fun(in.signal, i);
      double fc = cutoff.sample_fun(cutoff.signal, i);
      double k = RTBUF_SIGNAL_SAMPLERATE / (M_PI * fc);
      data->signal[i] = (x + data->x1 + (k - 1.0) * data->y1) / (1.0 + k);
      data->x1 = x;
      data->y1 = data->signal[i];
      i++;
    }
    return 0;
  }
  

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