94 lines
2.8 KiB
C
94 lines
2.8 KiB
C
|
/****************************************************************************
|
||
|
|
* libs/libdsp/lib_avg.c
|
||
|
|
*
|
||
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
||
|
|
* contributor license agreements. See the NOTICE file distributed with
|
||
|
|
* this work for additional information regarding copyright ownership. The
|
||
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
||
|
|
* "License"); you may not use this file except in compliance with the
|
||
|
|
* License. You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
||
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
||
|
|
* License for the specific language governing permissions and limitations
|
||
|
|
* under the License.
|
||
|
|
*
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Included Files
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
#include <dsp.h>
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
/* Based on video explanation of Dr. Shane Ross:
|
||
|
|
* https://www.youtube.com/watch?v=HCd-leV8OkU
|
||
|
|
*/
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Public Functions
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Name: avg_filter_data_init
|
||
|
|
*
|
||
|
|
* Description:
|
||
|
|
* Initialize the data struct used to store prev_avg and k parameter.
|
||
|
|
*
|
||
|
|
* Input Parameters:
|
||
|
|
* data - pointer to avg_filter_data_s
|
||
|
|
* prev_avg - initial value of prev_avg
|
||
|
|
* k - initial value of k counter
|
||
|
|
*
|
||
|
|
* Returned Value:
|
||
|
|
* None
|
||
|
|
*
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
void avg_filter_data_init(FAR struct avg_filter_data_s *data,
|
||
|
|
float prev_avg, float k)
|
||
|
|
{
|
||
|
|
LIBDSP_DEBUGASSERT(k > 0.0f)
|
||
|
|
|
||
|
|
data->prev_avg = prev_avg;
|
||
|
|
data->k = k;
|
||
|
|
}
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Name: avg_filter
|
||
|
|
*
|
||
|
|
* Description:
|
||
|
|
* Calculate the recurring average of a signal in the time
|
||
|
|
*
|
||
|
|
* Input Parameters:
|
||
|
|
* prev_avg - pointer to previous average variable
|
||
|
|
* k - pointer to k counter variable
|
||
|
|
* x - current signal value
|
||
|
|
*
|
||
|
|
* Returned Value:
|
||
|
|
* Average value
|
||
|
|
*
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
float avg_filter(FAR struct avg_filter_data_s *data, float x)
|
||
|
|
{
|
||
|
|
float alpha;
|
||
|
|
float avg;
|
||
|
|
|
||
|
|
LIBDSP_DEBUGASSERT(data != NULL);
|
||
|
|
|
||
|
|
alpha = (data->k - 1.0f) / data->k;
|
||
|
|
|
||
|
|
avg = (alpha * data->prev_avg) + ((1.0f - alpha) * x);
|
||
|
|
data->k += 1.0f;
|
||
|
|
|
||
|
|
data->prev_avg = avg;
|
||
|
|
|
||
|
|
return avg;
|
||
|
|
}
|
||
|
|
|