mirror of
https://github.com/libretro/scummvm.git
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249 lines
5.7 KiB
C++
249 lines
5.7 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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// Based on eos' (I)FFT code which is in turn
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// Based upon the (I)FFT code in FFmpeg
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// Copyright (c) 2008 Loren Merritt
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// Copyright (c) 2002 Fabrice Bellard
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// Partly based on libdjbfft by D. J. Bernstein
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#include "common/cosinetables.h"
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#include "common/fft.h"
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#include "common/util.h"
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namespace Common {
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FFT::FFT(int bits, int inverse) : _bits(bits), _inverse(inverse) {
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assert((_bits >= 2) && (_bits <= 16));
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int n = 1 << bits;
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_tmpBuf = new Complex[n];
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_expTab = new Complex[n / 2];
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_revTab = new uint16[n];
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_splitRadix = 1;
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for (int i = 0; i < n; i++)
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_revTab[-splitRadixPermutation(i, n, _inverse) & (n - 1)] = i;
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}
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FFT::~FFT() {
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delete[] _revTab;
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delete[] _expTab;
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delete[] _tmpBuf;
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}
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void FFT::permute(Complex *z) {
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int np = 1 << _bits;
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if (_tmpBuf) {
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for(int j = 0; j < np; j++)
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_tmpBuf[_revTab[j]] = z[j];
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memcpy(z, _tmpBuf, np * sizeof(Complex));
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return;
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}
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// Reverse
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for(int j = 0; j < np; j++) {
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int k = _revTab[j];
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if (k < j)
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SWAP(z[k], z[j]);
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}
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}
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int FFT::splitRadixPermutation(int i, int n, int inverse) {
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if (n <= 2)
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return i & 1;
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int m = n >> 1;
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if(!(i & m))
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return splitRadixPermutation(i, m, inverse) * 2;
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m >>= 1;
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if(inverse == !(i & m))
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return splitRadixPermutation(i, m, inverse) * 4 + 1;
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return splitRadixPermutation(i, m, inverse) * 4 - 1;
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}
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#define sqrthalf (float)M_SQRT1_2
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#define BF(x,y,a,b) {\
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x = a - b;\
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y = a + b;\
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}
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#define BUTTERFLIES(a0,a1,a2,a3) {\
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BF(t3, t5, t5, t1);\
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BF(a2.re, a0.re, a0.re, t5);\
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BF(a3.im, a1.im, a1.im, t3);\
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BF(t4, t6, t2, t6);\
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BF(a3.re, a1.re, a1.re, t4);\
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BF(a2.im, a0.im, a0.im, t6);\
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}
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// force loading all the inputs before storing any.
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// this is slightly slower for small data, but avoids store->load aliasing
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// for addresses separated by large powers of 2.
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#define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
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float r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
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BF(t3, t5, t5, t1);\
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BF(a2.re, a0.re, r0, t5);\
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BF(a3.im, a1.im, i1, t3);\
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BF(t4, t6, t2, t6);\
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BF(a3.re, a1.re, r1, t4);\
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BF(a2.im, a0.im, i0, t6);\
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}
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#define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
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t1 = a2.re * wre + a2.im * wim;\
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t2 = a2.im * wre - a2.re * wim;\
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t5 = a3.re * wre - a3.im * wim;\
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t6 = a3.im * wre + a3.re * wim;\
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BUTTERFLIES(a0,a1,a2,a3)\
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}
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#define TRANSFORM_ZERO(a0,a1,a2,a3) {\
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t1 = a2.re;\
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t2 = a2.im;\
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t5 = a3.re;\
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t6 = a3.im;\
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BUTTERFLIES(a0,a1,a2,a3)\
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}
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/* z[0...8n-1], w[1...2n-1] */
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#define PASS(name)\
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static void name(Complex *z, const float *wre, unsigned int n)\
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{\
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float t1, t2, t3, t4, t5, t6;\
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int o1 = 2*n;\
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int o2 = 4*n;\
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int o3 = 6*n;\
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const float *wim = wre+o1;\
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n--;\
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\
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TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
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TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
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do {\
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z += 2;\
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wre += 2;\
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wim -= 2;\
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TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
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TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
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} while(--n);\
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}
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PASS(pass)
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#undef BUTTERFLIES
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#define BUTTERFLIES BUTTERFLIES_BIG
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PASS(pass_big)
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#define DECL_FFT(t,n,n2,n4)\
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static void fft##n(Complex *z)\
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{\
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fft##n2(z);\
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fft##n4(z+n4*2);\
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fft##n4(z+n4*3);\
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pass(z,getCosineTable(t),n4/2);\
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}
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static void fft4(Complex *z)
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{
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float t1, t2, t3, t4, t5, t6, t7, t8;
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BF(t3, t1, z[0].re, z[1].re);
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BF(t8, t6, z[3].re, z[2].re);
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BF(z[2].re, z[0].re, t1, t6);
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BF(t4, t2, z[0].im, z[1].im);
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BF(t7, t5, z[2].im, z[3].im);
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BF(z[3].im, z[1].im, t4, t8);
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BF(z[3].re, z[1].re, t3, t7);
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BF(z[2].im, z[0].im, t2, t5);
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}
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static void fft8(Complex *z)
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{
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float t1, t2, t3, t4, t5, t6, t7, t8;
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fft4(z);
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BF(t1, z[5].re, z[4].re, -z[5].re);
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BF(t2, z[5].im, z[4].im, -z[5].im);
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BF(t3, z[7].re, z[6].re, -z[7].re);
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BF(t4, z[7].im, z[6].im, -z[7].im);
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BF(t8, t1, t3, t1);
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BF(t7, t2, t2, t4);
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BF(z[4].re, z[0].re, z[0].re, t1);
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BF(z[4].im, z[0].im, z[0].im, t2);
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BF(z[6].re, z[2].re, z[2].re, t7);
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BF(z[6].im, z[2].im, z[2].im, t8);
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TRANSFORM(z[1],z[3],z[5],z[7],sqrthalf,sqrthalf);
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}
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static void fft16(Complex *z)
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{
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float t1, t2, t3, t4, t5, t6;
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fft8(z);
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fft4(z+8);
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fft4(z+12);
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const float * const cosTable = getCosineTable(4);
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TRANSFORM_ZERO(z[0],z[4],z[8],z[12]);
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TRANSFORM(z[2],z[6],z[10],z[14],sqrthalf,sqrthalf);
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TRANSFORM(z[1],z[5],z[9],z[13],cosTable[1],cosTable[3]);
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TRANSFORM(z[3],z[7],z[11],z[15],cosTable[3],cosTable[1]);
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}
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DECL_FFT(5, 32,16,8)
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DECL_FFT(6, 64,32,16)
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DECL_FFT(7, 128,64,32)
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DECL_FFT(8, 256,128,64)
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DECL_FFT(9, 512,256,128)
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#define pass pass_big
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DECL_FFT(10, 1024,512,256)
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DECL_FFT(11, 2048,1024,512)
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DECL_FFT(12, 4096,2048,1024)
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DECL_FFT(13, 8192,4096,2048)
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DECL_FFT(14, 16384,8192,4096)
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DECL_FFT(15, 32768,16384,8192)
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DECL_FFT(16, 65536,32768,16384)
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static void (* const fft_dispatch[])(Complex*) = {
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fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
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fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
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};
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void FFT::calc(Complex *z) {
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fft_dispatch[_bits - 2](z);
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}
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} // End of namespace Common
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