/*****************************************************************************

    TRAVIS - Trajectory Analyzer and Visualizer

    http://www.travis-analyzer.de/

    Copyright (c) 2009-2026 Martin Brehm
                  2012-2017 Martin Thomas
                  2016-2020 Sascha Gehrke

    Please cite:  J. Chem. Phys. 2020, 152 (16), 164105.         (DOI 10.1063/5.0005078 )
                  J. Chem. Inf. Model. 2011, 51 (8), 2007-2023.  (DOI 10.1021/ci200217w )

    ---------------------------------------------------------------------------

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program 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 General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

*****************************************************************************/


#ifndef KISS_FFT_H
#define KISS_FFT_H


// This must always be the first include directive
#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>


/*
Copyright (c) 2003-2010, Mark Borgerding

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
    * Neither the author nor the names of any contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/



//#include <malloc.h>

//#ifdef __cplusplus
//extern "C" {
//#endif


#define KISS_FFT_API
#define KISS_FFT_MALLOC malloc
#define KISS_FFT_FREE free
#define kiss_fft_scalar double
#define KISS_FFT_ALIGN_CHECK(ptr)
#define KISS_FFT_ALIGN_SIZE_UP(size) (size)


typedef struct
{
    kiss_fft_scalar r;
    kiss_fft_scalar i;
} kiss_fft_cpx;

typedef struct kiss_fft_state *kiss_fft_cfg;

/* 
 *  kiss_fft_alloc
 *  
 *  Initialize a FFT (or IFFT) algorithm's cfg/state buffer.
 *
 *  typical usage:      kiss_fft_cfg mycfg=kiss_fft_alloc(1024,0,NULL,NULL);
 *
 *  The return value from fft_alloc is a cfg buffer used internally
 *  by the fft routine or NULL.
 *
 *  If lenmem is NULL, then kiss_fft_alloc will allocate a cfg buffer using malloc.
 *  The returned value should be free()d when done to avoid memory leaks.
 *  
 *  The state can be placed in a user supplied buffer 'mem':
 *  If lenmem is not NULL and mem is not NULL and *lenmem is large enough,
 *      then the function places the cfg in mem and the size used in *lenmem
 *      and returns mem.
 *  
 *  If lenmem is not NULL and ( mem is NULL or *lenmem is not large enough),
 *      then the function returns NULL and places the minimum cfg 
 *      buffer size in *lenmem.
 * */

kiss_fft_cfg kiss_fft_alloc(int nfft, int inverse_fft, void * mem,size_t *lenmem); 

/*
 * kiss_fft(cfg,in_out_buf)
 *
 * Perform an FFT on a complex input buffer.
 * for a forward FFT,
 * fin should be  f[0] , f[1] , ... ,f[nfft-1]
 * fout will be   F[0] , F[1] , ... ,F[nfft-1]
 * Note that each element is complex and can be accessed like
    f[k].r and f[k].i
 * */
void kiss_fft(kiss_fft_cfg cfg, const kiss_fft_cpx *fin, kiss_fft_cpx *fout);

/*
 A more generic version of the above function. It reads its input from every Nth sample.
 * */
void kiss_fft_stride(kiss_fft_cfg cfg, const kiss_fft_cpx *fin, kiss_fft_cpx *fout, int fin_stride);

/* If kiss_fft_alloc allocated a buffer, it is one contiguous 
   buffer and can be simply free()d when no longer needed*/
#define kiss_fft_free free

/*
 Cleans up some memory that gets managed internally. Not necessary to call, but it might clean up 
 your compiler output to call this before you exit.
*/
void kiss_fft_cleanup(void);
	

/*
 * Returns the smallest integer k, such that k>=n and k has only "fast" factors (2,3,5)
 */
int kiss_fft_next_fast_size(int n);

/* for real ffts, we need an even size */
#define kiss_fftr_next_fast_size_real(n) \
        (kiss_fft_next_fast_size( ((n)+1)>>1)<<1)

//#ifdef __cplusplus
//} 
//#endif

#endif
