www.pudn.com > FFTdemo.zip > fft.h

#ifndef __FFT_H__ 
#define __FFT_H__ 
 
/** 
 *  Pi for fft, float type. 
 */ 
#define PI 3.14159265358979323846 
 
/*  Complex type. 
 */ 
typedef struct { 
    float rex, imx; 
} Complex; 
 
/** 
 *  Decimation-in-Time Complex FFT Algorithm with Radix-2. 
 *  Note: 
 *    L   : exponent value of 2, N = 2^L. 
 *    cin : input complex array. 
 *    cout: output complex array. 
 */ 
void cfftr2( const int L,  
             const Complex *cin, Complex *cout); 
/** 
 *  in reverse FFT. 
 */ 
void cifftr2(const int L, 
             const Complex *cin, Complex *cout); 
/** 
 *  DFT Algorithm, with arbitrary N point. 
 *  Note: slow but sample, useful in verify other FFT algorithm. 
 */ 
void dft(const int N,  
         const Complex cin[], Complex cout[]); 
 
/** 
 *  Bit reverse sort, use reverse addition. 
 */ 
void revsort(const int N,  
             const Complex cin[], Complex cout[]); 
 
/** 
 *  Calculate the module and Normalize by LEVER. 
 */ 
void module(const Complex cin[],  
            float pout[], const int N, const int LEVER); 
 
#endif //__FFT_H__