add oversampler

oversampling/WDL/fft.h

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