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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
// Based on eos' cosine tables
#include "common/cosinetables.h"
#include "common/scummsys.h"
namespace Common {
CosineTable::CosineTable(int bitPrecision) {
assert((bitPrecision >= 4) && (bitPrecision <= 16));
_bitPrecision = bitPrecision;
_nPoints = 1 << _bitPrecision;
_radResolution = 2.0 * M_PI / _nPoints;
_refSize = _nPoints / 4;
_table = new float[_nPoints / 2];
// Table contains cos(2*pi*i/_nPoints) for 0<=i<=_nPoints/4,
// followed by 3_nPoints/4<=i<_nPoints
for (int i = 0; i <= _nPoints / 4; i++)
_table[i] = cos(i * _radResolution);
for (int i = 1; i < _nPoints / 4; i++)
_table[_nPoints / 2 - i] = _table[i];
}
float CosineTable::at(int index) const {
assert((index >= 0) && (index < _nPoints));
if (index < _refSize)
// [0,pi/2)
return _table[index];
if ((index > _refSize) && (index < 2 * _refSize))
// (pi/2,pi)
return -_table[2 * _refSize - index];
if ((index >= 2 * _refSize) && (index < 3 * _refSize))
// [pi,3/2pi)
return -_table[index - 2 * _refSize];
if ((index > 3 * _refSize) && (index < _nPoints))
// (3/2pi,2pi)
return _table[_nPoints - index];
return 0.0f; // cos(pi/2) and cos(3pi/2) = 0
}
CosineTable::~CosineTable() {
delete[] _table;
}
} // End of namespace Common
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