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

    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/>.

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


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

#include "kiss_fft.h"
#include <limits.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.
*/

/* kiss_fft.h
   defines kiss_fft_scalar as either short or a float type
   and defines
   typedef struct { kiss_fft_scalar r; kiss_fft_scalar i; }kiss_fft_cpx; */
 

#define MAXFACTORS 32
/* e.g. an fft of length 128 has 4 factors 
 as far as kissfft is concerned
 4*4*4*2
 */

struct kiss_fft_state
{
    int nfft;
    int inverse;
    int factors[2*MAXFACTORS];
    kiss_fft_cpx twiddles[1];
};

/*
  Explanation of macros dealing with complex math:

   C_MUL(m,a,b)         : m = a*b
   C_FIXDIV( c , div )  : if a fixed point impl., c /= div. noop otherwise
   C_SUB( res, a,b)     : res = a - b
   C_SUBFROM( res , a)  : res -= a
   C_ADDTO( res , a)    : res += a
 * */

#   define S_MUL(a,b) ( (a)*(b) )
#define C_MUL(m,a,b) \
    do{ (m).r = (a).r*(b).r - (a).i*(b).i;\
        (m).i = (a).r*(b).i + (a).i*(b).r; }while(0)
#   define C_FIXDIV(c,div) /* NOOP */
#   define C_MULBYSCALAR( c, s ) \
    do{ (c).r *= (s);\
        (c).i *= (s); }while(0)

#ifndef CHECK_OVERFLOW_OP
#  define CHECK_OVERFLOW_OP(a,op,b) /* noop */
#endif

#define  C_ADD( res, a,b)\
    do { \
	    CHECK_OVERFLOW_OP((a).r,+,(b).r)\
	    CHECK_OVERFLOW_OP((a).i,+,(b).i)\
	    (res).r=(a).r+(b).r;  (res).i=(a).i+(b).i; \
    }while(0)
#define  C_SUB( res, a,b)\
    do { \
	    CHECK_OVERFLOW_OP((a).r,-,(b).r)\
	    CHECK_OVERFLOW_OP((a).i,-,(b).i)\
	    (res).r=(a).r-(b).r;  (res).i=(a).i-(b).i; \
    }while(0)
#define C_ADDTO( res , a)\
    do { \
	    CHECK_OVERFLOW_OP((res).r,+,(a).r)\
	    CHECK_OVERFLOW_OP((res).i,+,(a).i)\
	    (res).r += (a).r;  (res).i += (a).i;\
    }while(0)

#define C_SUBFROM( res , a)\
    do {\
	    CHECK_OVERFLOW_OP((res).r,-,(a).r)\
	    CHECK_OVERFLOW_OP((res).i,-,(a).i)\
	    (res).r -= (a).r;  (res).i -= (a).i; \
    }while(0)


#  define KISS_FFT_COS(phase) (kiss_fft_scalar) cos(phase)
#  define KISS_FFT_SIN(phase) (kiss_fft_scalar) sin(phase)
#  define HALF_OF(x) ((x)*((kiss_fft_scalar).5))

#define  kf_cexp(x,phase) \
	do{ \
		(x)->r = KISS_FFT_COS(phase);\
		(x)->i = KISS_FFT_SIN(phase);\
	}while(0)


/* a debugging function */
#define pcpx(c)\
    fprintf(stderr,"%g + %gi\n",(double)((c)->r),(double)((c)->i) )


#ifdef KISS_FFT_USE_ALLOCA
// define this to allow use of alloca instead of malloc for temporary buffers
// Temporary buffers are used in two case: 
// 1. FFT sizes that have "bad" factors. i.e. not 2,3 and 5
// 2. "in-place" FFTs.  Notice the quotes, since kissfft does not really do an in-place transform.
#include <alloca.h>
#define  KISS_FFT_TMP_ALLOC(nbytes) alloca(nbytes)
#define  KISS_FFT_TMP_FREE(ptr) 
#else
#define  KISS_FFT_TMP_ALLOC(nbytes) KISS_FFT_MALLOC(nbytes)
#define  KISS_FFT_TMP_FREE(ptr) KISS_FFT_FREE(ptr)
#endif
