/*
 *  Copyright (c) 2003-2010, Mark Borgerding. All rights reserved.
 *  This file is part of KISS FFT - https://github.com/mborgerding/kissfft
 *
 *  SPDX-License-Identifier: BSD-3-Clause
 *  See COPYING file for more information.
 */

#ifndef KISS_FFT_H
#define KISS_FFT_H

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

#ifdef __cplusplus
extern "C"
{
#endif

/*
 ATTENTION!
 If you would like a :
 -- a utility that will handle the caching of fft objects
 -- real-only (no imaginary time component ) FFT
 -- a multi-dimensional FFT
 -- a command-line utility to perform ffts
 -- a command-line utility to perform fast-convolution filtering

 Then see kfc.h kiss_fftr.h kiss_fftnd.h fftutil.c kiss_fastfir.c
  in the tools/ directory.
*/

/* User may override KISS_FFT_MALLOC and/or KISS_FFT_FREE. */
#ifdef USE_SIMD
#include <xmmintrin.h>
#define kiss_fft_scalar __m128
#ifndef KISS_FFT_MALLOC
#define KISS_FFT_MALLOC(nbytes) _mm_malloc(nbytes, 16)
#endif
#ifndef KISS_FFT_FREE
#define KISS_FFT_FREE _mm_free
#endif
#else
#ifndef KISS_FFT_MALLOC
#define KISS_FFT_MALLOC malloc
#endif
#ifndef KISS_FFT_FREE
#define KISS_FFT_FREE free
#endif
#endif

#ifdef FIXED_POINT
#include <stdint.h>
#if (FIXED_POINT == 32)
#define kiss_fft_scalar int32_t
#else
#define kiss_fft_scalar int16_t
#endif
#else
#ifndef kiss_fft_scalar
/*  default is float    @mhall: changed to double*/
#define kiss_fft_scalar double
#endif
#endif

	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 KISS_FFT_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
