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

#include  
#include  
 
#include  
 
#include "fft.h" 
 
/** 
 *  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[]) 
{ 
    assert(cin); 
    assert(cout); 
    assert(L>0); 
    const int N = 1<>= 1;  /* len_sd /= 2 */ 
        len_cl <<= 1;  /* len_cl *= 2 */ 
    } 
} 
 
/** 
 *  in reverse FFT. see cfftr2(); 
 */ 
void cifftr2(const int L, 
             const Complex *cin, Complex *cout) 
{ 
    assert(cin); 
    assert(cout); 
    assert(L>0); 
     
    const int N = 1<0); 
     
    /* Loop for each X(k). 
     */ 
    int k; 
    for (k=0; k0); 
 
    /* Reconstruct data for output. 
     */ 
    float gmax = 1; 
    int i; 
    for (i=0; i gmax)  
        { 
            gmax = pout[i]; 
        } 
    } 
    /* Normalize data. 
     */ 
    for (i=0; i0); 
     
    int ri = 0, i; 
    const int N2 = N/2, N1=N-1; 
    /* copy data to cout */ 
    for (i=0; i