d_fft_fftw.c

/* Copyright (c) 1997- Miller Puckette and others.
* For information on usage and redistribution, and for a DISCLAIMER OF ALL
* WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */

/* --------- Pd interface to FFTW library; imitate Mayer API ---------- */

/* changes and additions for FFTW3 by Thomas Grill                      */

#include "m_pd.h"
#include <fftw3.h>

int ilog2(int n);

#define MINFFT 0
#define MAXFFT 30

/* from the FFTW website:
 #include <fftw3.h>
     ...
     {
         fftw_complex *in, *out;
     fftw_plan p;
     ...
         in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);
         out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);
         p = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
     ...
         fftw_execute(p); 
     ...
     fftw_destroy_plan(p);  
         fftw_free(in); fftw_free(out);
     }

FFTW_FORWARD or FFTW_BACKWARD, and indicates the direction of the transform you
are interested in. Alternatively, you can use the sign of the exponent in the
transform, -1 or +1, which corresponds to FFTW_FORWARD or FFTW_BACKWARD
respectively. The flags argument is either FFTW_MEASURE

*/

/* complex stuff */

typedef struct {
    fftwf_plan plan;
    fftwf_complex *in,*out;
} cfftw_info;

static cfftw_info cfftw_fwd[MAXFFT+1 - MINFFT],cfftw_bwd[MAXFFT+1 - MINFFT];

static cfftw_info *cfftw_getplan(int n,int fwd)
{
    cfftw_info *info;
    int logn = ilog2(n);
    if (logn < MINFFT || logn > MAXFFT)
        return (0);
    info = (fwd?cfftw_fwd:cfftw_bwd)+(logn-MINFFT);
    if (!info->plan) 
    {
        info->in = (fftwf_complex*) fftwf_malloc(sizeof(fftwf_complex) * n);
        info->out = (fftwf_complex*) fftwf_malloc(sizeof(fftwf_complex) * n);
        info->plan = fftwf_plan_dft_1d(n, info->in, info->out, fwd?FFTW_FORWARD:FFTW_BACKWARD, FFTW_MEASURE);        
    }
    return info;
}


/* real stuff */

typedef struct {
    fftwf_plan plan;
    t_float *in,*out;
} rfftw_info;

static rfftw_info rfftw_fwd[MAXFFT+1 - MINFFT],rfftw_bwd[MAXFFT+1 - MINFFT];

static rfftw_info *rfftw_getplan(int n,int fwd)
{
    rfftw_info *info;
    int logn = ilog2(n);
    if (logn < MINFFT || logn > MAXFFT)
        return (0);
    info = (fwd?rfftw_fwd:rfftw_bwd)+(logn-MINFFT);
    if (!info->plan) 
    {
        info->in = (t_float*) fftwf_malloc(sizeof(t_float) * n);
        info->out = (t_float*) fftwf_malloc(sizeof(t_float) * n);
        info->plan = fftwf_plan_r2r_1d(n, info->in, info->out, fwd?FFTW_R2HC:FFTW_HC2R, FFTW_MEASURE);
    }
    return info;
}



EXTERN void mayer_fht(t_float *fz, int n)
{
    post("FHT: not yet implemented");
}

static void mayer_do_cfft(int n, t_float *fz1, t_float *fz2, int fwd)
{
    int i;
    t_float *fz;
    cfftw_info *p = cfftw_getplan(n, fwd);
    if (!p)
        return;
        
    for (i = 0, fz = (t_float *)p->in; i < n; i++)
        fz[i*2] = fz1[i], fz[i*2+1] = fz2[i];
        
    fftwf_execute(p->plan);
    
    for (i = 0, fz = (t_float *)p->out; i < n; i++)
        fz1[i] = fz[i*2], fz2[i] = fz[i*2+1];
}

EXTERN void mayer_fft(int n, t_float *fz1, t_float *fz2)
{
    mayer_do_cfft(n, fz1, fz2, 1);
}

EXTERN void mayer_ifft(int n, t_float *fz1, t_float *fz2)
{
    mayer_do_cfft(n, fz1, fz2, 0);
}

/* 
    in the following the sign flips are done to 
    be compatible with the mayer_fft implementation,
    but it's probably the mayer_fft that should be corrected...
*/ 

EXTERN void mayer_realfft(int n, t_float *fz)
{
    int i;
    rfftw_info *p = rfftw_getplan(n, 1);
    if (!p)
        return;
        
    for (i = 0; i < n; i++)
        p->in[i] = fz[i];
    fftwf_execute(p->plan);
    for (i = 0; i < n/2+1; i++)
        fz[i] = p->out[i];
    for (; i < n; i++)
        fz[i] = -p->out[i];
}

EXTERN void mayer_realifft(int n, t_float *fz)
{
    int i;
    rfftw_info *p = rfftw_getplan(n, 0);
    if (!p)
        return;
        
    for (i = 0; i < n/2+1; i++)
        p->in[i] = fz[i];
    for (; i < n; i++)
        p->in[i] = -fz[i];    
    fftwf_execute(p->plan);
    for (i = 0; i < n; i++)
        fz[i] = p->out[i];
}