fft.scm

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|#

;; bindings for The Fastest Fourier Transform in the South (FFTS) library
(include "fft-tests.scm")

(c-declare  #<<end-of-c-declare

#include <string.h>
#include "ffts/ffts.h"

int fft_sign(float *data, float *data_out, int n, int sign){
  ffts_plan_t *fft = ffts_init_1d(n, sign);
  if(!fft) return 0;
  float *in = malloc(sizeof(float)*n*2);
  float *out = malloc(sizeof(float)*n*2);
  memcpy(in, data, sizeof(float)*n*2);
  memcpy(out, data_out, sizeof(float)*n*2);
  ffts_execute(fft, in, out);
  memcpy(data_out, out, sizeof(float)*n*2);
  ffts_free(fft);
  free(in);
  free(out);
  if (sign == 1){
    int i;
    for (i=0;i<n*2;i++){
      data_out[i]/=n;
    }
  }
  return 1;
}

int fft2_sign(float *data, float *data_out, size_t n, size_t n2, int sign){
  ffts_plan_t *fft = ffts_init_2d(n, n2, sign);
  if(!fft) return 0;
  float *in = malloc(sizeof(float)*n*n2*2);
  float *out = malloc(sizeof(float)*n*n2*2);
  memcpy(in, data, sizeof(float)*n*n2*2);
  memcpy(out, data_out, sizeof(float)*n*n2*2);
  ffts_execute(fft, in, out);
  memcpy(data_out, out, sizeof(float)*n*n2*2);
  ffts_free(fft);
  free(in);
  free(out);
  if (sign == 1){
    int i;
    for (i=0;i<n*2;i++){
      data_out[i]/=n*n2;
    }
  }
  return 1;
}

int fftn_sign(float *data, float *data_out, int rank, size_t *Ns, int sign){
  ffts_plan_t *fft = ffts_init_nd(rank, Ns, sign);
  if(!fft) return 0;
  ffts_execute(fft, data, data_out);
  ffts_free(fft);
  return 1;
}

end-of-c-declare
)

(define (fft_sign lst sign)
  (let* ((infl (list->f32vector (apply append (map (lambda (c) (list (flo (real-part c)) (flo (imag-part c)))) lst))))
         (outfl (make-f32vector (f32vector-length infl) 0.)))
    (if ((c-lambda (scheme-object scheme-object int int) bool
      "___result=fft_sign(___CAST(float*,___BODY_AS(___arg1,___tSUBTYPED)),
                ___CAST(float*,___BODY_AS(___arg2,___tSUBTYPED)),
                ___arg3,___arg4);")
           infl outfl (length lst) sign)
      (let loop ((lst (f32vector->list outfl)) (ret (list)))
        (if (null? lst)
          ret
          (loop (cddr lst) (append ret (list (+ (car lst) (* (cadr lst) +i)))))
        ))
      #f
    )
  ))
(define (fft lst) (fft_sign lst -1))
(define (ifft lst) (fft_sign lst 1))

(define (fft2_sign lstlst sign)
  (let* ((rows (length lstlst))
         (cols (length (car lstlst)))
         (infl (list->f32vector (apply append (map (lambda (c)
                 (list (flo (real-part c)) (flo (imag-part c)))) (listlist-flatten lstlst)))))
         (outfl (make-f32vector (f32vector-length infl) 0.)))
    (if ((c-lambda (scheme-object scheme-object int int int) bool
      "___result=fft2_sign(___CAST(float*,___BODY_AS(___arg1,___tSUBTYPED)),
                ___CAST(float*,___BODY_AS(___arg2,___tSUBTYPED)),
                ___arg3,___arg4,___arg5);")
           infl outfl rows cols sign)
      (let loop ((lst (f32vector->list outfl)) (ret (list)))
        (if (null? lst)
          (let loopr ((r 0) (retm '()))
            (if (fx= r rows)
              retm
              (loopr (fx+ r 1) (append retm (list
                (let loopc ((c 0) (reti '()))
                  (if (fx= c cols)
                    reti
                    (loopc (fx+ c 1) (append reti (list (list-ref ret (+ (* r cols) c)))))
                  )
                )
              )))
            ))
          (loop (cddr lst) (append ret (list (+ (car lst) (* (cadr lst) +i)))))
        ))
      #f
    )
  ))
(define (fft2 lstlst) (fft2_sign lstlst -1))
(define (ifft2 lstlst) (fft2_sign lstlst 1))


;; eof