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/**
* @file llfft.h
* @brief FFT function definitions
*
* Copyright (c) 2003-2007, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlife.com/developers/opensource/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at http://secondlife.com/developers/opensource/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
*/
#ifndef LL_LLFFT_H
#define LL_LLFFT_H
/*
* Fast Fourier Transform
*
*/
//#include <stdio.h>
//#include <math.h>
#include "llmath.h"
#define FORWARD 0
#define INVERSE 1
typedef struct {F32 re; F32 im;} COMPLEX;
typedef struct {F64 re; F64 im;} DPCOMPLEX;
void FFT842(S32 in, S32 n, DPCOMPLEX *b);
void R2TX(S32 nthpo, DPCOMPLEX *c0, DPCOMPLEX *c1);
void R4TX(S32 nthpo, DPCOMPLEX *c0, DPCOMPLEX *c1, DPCOMPLEX *c2, DPCOMPLEX *c3);
void R8TX(S32 nxtlt, S32 nthpo, S32 lengt, DPCOMPLEX *cc0, DPCOMPLEX *cc1, DPCOMPLEX *cc2,
DPCOMPLEX *cc3, DPCOMPLEX *cc4, DPCOMPLEX *cc5, DPCOMPLEX *cc6, DPCOMPLEX *cc7);
S32 power_of_2(S32 n);
S32 fastlog2(S32 n);
class LLFFTPlan
{
private:
S32 mRows;
S32 mCols;
S32 mSize;
DPCOMPLEX* mBuff;
public:
LLFFTPlan() : mRows(0), mCols(0), mSize(0), mBuff(0) {}
LLFFTPlan(S32 rows, S32 cols) { init(rows, cols); }
~LLFFTPlan() { destroy(); }
void init(S32 rows, S32 cols)
{
if(power_of_2(rows) && power_of_2(cols))
{
mRows = rows;
mCols = cols;
mSize = mRows > mCols ? mRows : mCols;
mBuff = new DPCOMPLEX[mSize];
}
}
void destroy()
{
delete [] mBuff;
mSize = 0;
}
BOOL valid() const { return mBuff != NULL; }
DPCOMPLEX* buffer() const { return mBuff; }
S32 rows() const { return mRows; }
S32 cols() const { return mCols; }
};
S32 fft(const LLFFTPlan& plan, COMPLEX *array, S32 rows, S32 cols, S32 direction);
/* do forward transform. array must be COMPLEX */
inline S32 forward_fft(const LLFFTPlan& plan, COMPLEX *array, S32 rows, S32 cols)
{
return fft(plan, array, rows, cols, FORWARD);
}
/* do inverse transform. array must be COMPLEX */
inline S32 inverse_fft(const LLFFTPlan& plan, COMPLEX *array, S32 rows, S32 cols)
{
return fft(plan, array, rows, cols, INVERSE);
}
#endif
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