dspl/fft__shift_8c_source.html

/*

* Copyright (c) 2015-2024 Sergey Bakhurin

* Digital Signal Processing Library [http://dsplib.org]

*

* This file is part of libdspl-2.0.

*

* is free software: you can redistribute it and/or modify

* it under the terms of the GNU Lesser    General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* DSPL is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.    See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU Lesser General Public License

* along with Foobar.    If not, see <http://www.gnu.org/licenses/>.

*/


#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <float.h>


#include "dspl.h"


#ifdef DOXYGEN_ENGLISH


#endif

#ifdef DOXYGEN_RUSSIAN


#endif

int DSPL_API fft_shift(double* x, int n, double* y)

{

    int n2, r;

    int k;

    double tmp;

    double *buf;


    if(!x || !y)

        return ERROR_PTR;


    if(n<1)

        return ERROR_SIZE;


    r = n%2;

    if(!r)

    {

        n2 = n>>1;

        for(k = 0; k < n2; k++)

        {

            tmp = x[k];

            y[k] = x[k+n2];

            y[k+n2] = tmp;

        }

    }

    else

    {

        n2 = (n+1) >> 1;

        buf = (double*) malloc(n2*sizeof(double));

        memcpy(buf, x, n2*sizeof(double));

        memcpy(y, x+n2, (n2-1)*sizeof(double));

        memcpy(y+n2-1, buf, n2*sizeof(double));

        free(buf);

    }

    return RES_OK;

}