view src/xtract_window_private.h @ 214:f28f66faa016

Add "stateful" feature type with initial feature "last n"

Stateful feature extraction functions are functions that require state to be maintained between successive calls.  This is necessary, for example when an accumulation of values is required, or changes need to be measured over time.

The initial xtract_last_n() function accumulates the last N (single) values from *data and writes them to *result

/*
 * Copyright (C) 2012 Jamie Bullock
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

/* xtract_window_private.h: declares window generation functions */

#define PI 3.1415926535897931

/** \brief generate a Gaussian window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 * \param sd the standard deviation of the "distribution" represented by the Gaussian curve. The higher the value of sd, the wider the curve. Generally sd <= 0.5
 *
 */
void gauss(double *window, const int N, const double sd);

/** \brief generate a Hamming window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void hamming(double *window, const int N);

/** \brief generate a Hann window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void hann(double *window, const int N);

/** \brief generate a Bartlett window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void bartlett(double *window, const int N);

/** \brief generate a Triangular window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void triangular(double *window, const int N);

/** \brief generate a Bartlett-Hann  window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void bartlett_hann(double *window, const int N);

/** \brief generate a Blackman window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void blackman(double *window, const int N);

/** \brief generate a Kaiser window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 * \param alpha The larger the value of |alpha|, the narrower the window becomes
 *
 */
void kaiser(double *window, const int N, const double alpha);

/** \brief generate a Blackman-Harris window
 *
 * \param *window a pointer to an array to contain the window data
 * \param N the number of elements in the array pointed to by *window
 *
 */
void blackman_harris(double *window, const int N);