view src/helper.c @ 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.
 *
 */

/* helper.c: helper functions. */

#include <stdio.h>

#include "../xtract/libxtract.h"

#ifdef WORDS_BIGENDIAN
#define INDEX 0
#else
#define INDEX 1
#endif

int xtract_windowed(const double *data, const int N, const void *argv, double *result)
{

    int n;
    const double *window;

    n = N;
    window = (const double *)argv;

    while(n--)
        result[n] = data[n] * window[n];

    return XTRACT_SUCCESS;

}

int xtract_features_from_subframes(const double *data, const int N, const int feature, const void *argv, double *result)
{

    const double *frame1,
          *frame2;
    double *result1,
          *result2;

    int n, rv;

    n = N >> 1;

    frame1 = data;
    frame2 = data + n;
    result1 = result;
    result2 = result + n;

    rv = xtract[feature](frame1, n, argv, result1);

    if(rv == XTRACT_SUCCESS)
        rv = xtract[feature](frame2, n, argv, result2);

    return rv;

}

//inline int xtract_is_denormal(double const d)
int xtract_is_denormal(double const d)
{
    if(sizeof(d) != 2 * sizeof(int))
        fprintf(stderr, "libxtract: Error: xtract_is_denormal() detects inconsistent wordlength for type 'double'\n");

    int l = ((int *)&d)[INDEX];
    return (l&0x7ff00000) == 0 && d!=0; //Check for 0 may not be necessary
}

//inline bool xtract_is_poweroftwo(unsigned int x)
bool xtract_is_poweroftwo(unsigned int x)
{
    return ((x != 0) && !(x & (x - 1)));
}