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cf99bb0a5e
When the constructor for the cos/sin table was changed from number of bits to number of points all usages thoughout the code should of been changed, but this was missed in RDFT and DCT. Fixes Trac#10683.
101 lines
2.9 KiB
C++
101 lines
2.9 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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*
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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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*
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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)RDFT code which is in turn
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// Based upon the (I)RDFT code in FFmpeg
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// Copyright (c) 2009 Alex Converse <alex dot converse at gmail dot com>
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#include "common/rdft.h"
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namespace Common {
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RDFT::RDFT(int bits, TransformType trans) : _bits(bits), _sin(1 << bits), _cos(1 << bits), _fft(nullptr) {
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assert((_bits >= 4) && (_bits <= 16));
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_inverse = trans == IDFT_C2R || trans == DFT_C2R;
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_signConvention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
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_fft = new FFT(bits - 1, trans == IDFT_C2R || trans == IDFT_R2C);
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int n = 1 << bits;
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_tSin = _sin.getTable() + (trans == DFT_R2C || trans == DFT_C2R) * (n >> 2);
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_tCos = _cos.getTable();
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}
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RDFT::~RDFT() {
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delete _fft;
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}
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void RDFT::calc(float *data) {
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const int n = 1 << _bits;
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const float k1 = 0.5f;
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const float k2 = 0.5f - _inverse;
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if (!_inverse) {
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_fft->permute((Complex *)data);
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_fft->calc ((Complex *)data);
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}
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Complex ev, od;
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/* i=0 is a special case because of packing, the DC term is real, so we
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are going to throw the N/2 term (also real) in with it. */
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ev.re = data[0];
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data[0] = ev.re + data[1];
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data[1] = ev.re - data[1];
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int i;
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for (i = 1; i < (n >> 2); i++) {
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int i1 = 2 * i;
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int i2 = n - i1;
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/* Separate even and odd FFTs */
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ev.re = k1 * (data[i1 ] + data[i2 ]);
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od.im = -k2 * (data[i1 ] - data[i2 ]);
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ev.im = k1 * (data[i1 + 1] - data[i2 + 1]);
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od.re = k2 * (data[i1 + 1] + data[i2 + 1]);
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/* Apply twiddle factors to the odd FFT and add to the even FFT */
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data[i1 ] = ev.re + od.re * _tCos[i] - od.im * _tSin[i];
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data[i1 + 1] = ev.im + od.im * _tCos[i] + od.re * _tSin[i];
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data[i2 ] = ev.re - od.re * _tCos[i] + od.im * _tSin[i];
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data[i2 + 1] = -ev.im + od.im * _tCos[i] + od.re * _tSin[i];
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}
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data[2 * i + 1] = _signConvention * data[2 * i + 1];
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if (_inverse) {
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data[0] *= k1;
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data[1] *= k1;
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_fft->permute((Complex *)data);
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_fft->calc ((Complex *)data);
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}
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}
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} // End of namespace Common
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