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77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
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/*
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WDL - fft.h
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Copyright (C) 2006 and later Cockos Incorporated
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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This file defines the interface to the WDL FFT library. These routines are based on the
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DJBFFT library, which are Copyright 1999 D. J. Bernstein, djb@pobox.com
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The DJB FFT web page is: http://cr.yp.to/djbfft.html
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*/
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#ifndef _WDL_FFT_H_
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#define _WDL_FFT_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef WDL_FFT_REALSIZE
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#define WDL_FFT_REALSIZE 4
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#endif
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#if WDL_FFT_REALSIZE == 4
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typedef float WDL_FFT_REAL;
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#elif WDL_FFT_REALSIZE == 8
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typedef double WDL_FFT_REAL;
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#else
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#error invalid FFT item size
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#endif
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typedef struct {
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WDL_FFT_REAL re;
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WDL_FFT_REAL im;
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} WDL_FFT_COMPLEX;
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extern void WDL_fft_init();
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extern void WDL_fft_complexmul(WDL_FFT_COMPLEX *dest, WDL_FFT_COMPLEX *src, int len);
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extern void WDL_fft_complexmul2(WDL_FFT_COMPLEX *dest, WDL_FFT_COMPLEX *src, WDL_FFT_COMPLEX *src2, int len);
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extern void WDL_fft_complexmul3(WDL_FFT_COMPLEX *destAdd, WDL_FFT_COMPLEX *src, WDL_FFT_COMPLEX *src2, int len);
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/* Expects WDL_FFT_COMPLEX input[0..len-1] scaled by 1.0/len, returns
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WDL_FFT_COMPLEX output[0..len-1] order by WDL_fft_permute(len). */
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extern void WDL_fft(WDL_FFT_COMPLEX *, int len, int isInverse);
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/* Expects WDL_FFT_REAL input[0..len-1] scaled by 0.5/len, returns
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WDL_FFT_COMPLEX output[0..len/2-1], for len >= 4 order by
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WDL_fft_permute(len/2). Note that output[len/2].re is stored in
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output[0].im. */
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extern void WDL_real_fft(WDL_FFT_REAL *, int len, int isInverse);
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extern int WDL_fft_permute(int fftsize, int idx);
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extern int *WDL_fft_permute_tab(int fftsize);
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#ifdef __cplusplus
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};
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#endif
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#endif
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