WDL/fft.h

   1 /*
   2   WDL - fft.h
   3   Copyright (C) 2006 and later Cockos Incorporated
   4
   5   This software is provided 'as-is', without any express or implied
   6   warranty.  In no event will the authors be held liable for any damages
   7   arising from the use of this software.
   8
   9   Permission is granted to anyone to use this software for any purpose,
  10   including commercial applications, and to alter it and redistribute it
  11   freely, subject to the following restrictions:
  12
  13   1. The origin of this software must not be misrepresented; you must not
  14      claim that you wrote the original software. If you use this software
  15      in a product, an acknowledgment in the product documentation would be
  16      appreciated but is not required.
  17   2. Altered source versions must be plainly marked as such, and must not be
  18      misrepresented as being the original software.
  19   3. This notice may not be removed or altered from any source distribution.
  20
  21
  22
  23   This file defines the interface to the WDL FFT library. These routines are based on the
  24   DJBFFT library, which are   Copyright 1999 D. J. Bernstein, djb@pobox.com
  25
  26   The DJB FFT web page is:  http://cr.yp.to/djbfft.html
  27
  28 */
  29
  30 #ifndef _WDL_FFT_H_
  31 #define _WDL_FFT_H_
  32
  33 #ifdef __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 #ifndef WDL_FFT_REALSIZE
  38 #define WDL_FFT_REALSIZE 4
  39 #endif
  40
  41 #if WDL_FFT_REALSIZE == 4
  42 typedef float WDL_FFT_REAL;
  43 #elif WDL_FFT_REALSIZE == 8
  44 typedef double WDL_FFT_REAL;
  45 #else
  46 #error invalid FFT item size
  47 #endif
  48
  49 typedef struct {
  50   WDL_FFT_REAL re;
  51   WDL_FFT_REAL im;
  52 } WDL_FFT_COMPLEX;
  53
  54 extern void WDL_fft_init();
  55
  56 extern void WDL_fft_complexmul(WDL_FFT_COMPLEX *dest, WDL_FFT_COMPLEX *src, int len);
  57 extern void WDL_fft_complexmul2(WDL_FFT_COMPLEX *dest, WDL_FFT_COMPLEX *src, WDL_FFT_COMPLEX *src2, int len);
  58 extern void WDL_fft_complexmul3(WDL_FFT_COMPLEX *destAdd, WDL_FFT_COMPLEX *src, WDL_FFT_COMPLEX *src2, int len);
  59
  60 /* Expects WDL_FFT_COMPLEX input[0..len-1] scaled by 1.0/len, returns
  61 WDL_FFT_COMPLEX output[0..len-1] order by WDL_fft_permute(len). */
  62 extern void WDL_fft(WDL_FFT_COMPLEX *, int len, int isInverse);
  63
  64 /* Expects WDL_FFT_REAL input[0..len-1] scaled by 0.5/len, returns
  65 WDL_FFT_COMPLEX output[0..len/2-1], for len >= 4 order by
  66 WDL_fft_permute(len/2). Note that output[len/2].re is stored in
  67 output[0].im. */
  68 extern void WDL_real_fft(WDL_FFT_REAL *, int len, int isInverse);
  69
  70 extern int WDL_fft_permute(int fftsize, int idx);
  71 extern int *WDL_fft_permute_tab(int fftsize);
  72
  73 #ifdef __cplusplus
  74 };
  75 #endif
  76
  77 #endif