ref: 926aff456d7ee4318c86f6757c38c8a0174dbbf7
dir: /kiss_fft.h/
#ifndef KISS_FFT_H
#define KISS_FFT_H
#ifdef __cplusplus
extern "C" {
#endif
#define KISS_FFT_MALLOC malloc
#define KISS_FFT_FREE free
#ifdef FIXED_POINT
# if (FIXED_POINT == 32)
# define kiss_fft_scalar s32int
# else
# define kiss_fft_scalar s16int
# endif
#else
# ifndef kiss_fft_scalar
/* default is 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;
#pragma incomplete 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); for FFT
* kiss_fft_cfg *mycfg=kiss_fft_alloc(1024,1,NULL,NULL); for IFFT
*
* The return value from fft_alloc is a cfg buffer used internally
* by the fft routine or NULL.
*
* The inverse FFT is calculated if inverse_fft is non-zero.
*
* 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, usize * 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
/*
* 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