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80 lines
2.4 KiB
C++
80 lines
2.4 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' cosine tables
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#include "common/cosinetables.h"
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#include "common/scummsys.h"
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namespace Common {
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CosineTable::CosineTable(int nPoints) {
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assert((nPoints >= 16) && (nPoints <= 65536)); // log2 space is in [4,16]
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assert(nPoints % 4 == 0);
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_nPoints = nPoints;
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_radResolution = 2.0 * M_PI / _nPoints;
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_refSize = _nPoints / 4;
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_tableEOS = new float[_nPoints / 2];
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_table = new float[_nPoints];
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for (int i = 0; i < _nPoints; i++)
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_table[i] = cos(i * _radResolution);
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// Table contains cos(2*pi*i/_nPoints) for 0<=i<=_nPoints/4,
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// followed by 3_nPoints/4<=i<_nPoints
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for (int i = 0; i <= _nPoints / 4; i++)
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_tableEOS[i] = cos(i * _radResolution);
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for (int i = 1; i < _nPoints / 4; i++)
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_tableEOS[_nPoints / 2 - i] = _tableEOS[i];
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}
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float CosineTable::at(int index) const {
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assert((index >= 0) && (index < _nPoints));
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return _table[index];
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}
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float CosineTable::atLegacy(int index) const {
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assert((index >= 0) && (index < _nPoints));
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if (index < _refSize)
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// [0,pi/2)
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return _tableEOS[index];
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if ((index > _refSize) && (index < 2 * _refSize))
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// (pi/2,pi)
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return -_tableEOS[2 * _refSize - index];
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if ((index >= 2 * _refSize) && (index < 3 * _refSize))
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// [pi,3/2pi)
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return -_tableEOS[index - 2 * _refSize];
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if ((index > 3 * _refSize) && (index < _nPoints))
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// (3/2pi,2pi)
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return _tableEOS[_nPoints - index];
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return 0.0f; // cos(pi/2) and cos(3pi/2) = 0
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}
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CosineTable::~CosineTable() {
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delete[] _tableEOS;
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delete[] _table;
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}
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} // End of namespace Common
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