annotate dsp/transforms/kissfft/kiss_fft.h @ 73:dcb555b90924

* Key detector: when returning key strengths, use the peak value of the
  three underlying chromagram correlations (from 36-bin chromagram)
  corresponding to each key, instead of the mean.
  Rationale: This is the same method as used when returning the key value,
  and it's nice to have the same results in both returned value and plot.
  The peak performed better than the sum with a simple test set of triads,
  so it seems reasonable to change the plot to match the key output rather
  than the other way around.

* FFT: kiss_fftr returns only the non-conjugate bins, synthesise the rest
  rather than leaving them (perhaps dangerously) undefined.  Fixes an
  uninitialised data error in chromagram that could cause garbage results
  from key detector.

* Constant Q: remove precalculated values again, I reckon they're not
  proving such a good tradeoff.

#ifndef KISS_FFT_H
#define KISS_FFT_H

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <memory.h>
#ifdef __APPLE__
#include <malloc/malloc.h>
#else
#include <malloc.h>
#endif

#ifdef __cplusplus
extern "C" {
#endif

#ifdef USE_SIMD
# include <xmmintrin.h>
# define kiss_fft_scalar __m128
#define KISS_FFT_MALLOC(nbytes) memalign(16,nbytes)
#else	
#define KISS_FFT_MALLOC malloc
#endif	


#ifdef FIXED_POINT
#include <sys/types.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 */
/* #   define kiss_fft_scalar float */
/* ... but doubles for QM library ... */
#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 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);

#ifdef __cplusplus
} 
#endif

#endif