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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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
// Based on eos' sine tables
#include "math/sinetables.h"
namespace Math {
SineTable::SineTable(int nPoints) {
assert((nPoints >= 16) && (nPoints <= 65536)); // log2 space is in [4,16]
assert(nPoints % 4 == 0);
_nPoints = nPoints;
_radResolution = 2.0 * M_PI / _nPoints;
_refSize = _nPoints / 4;
_tableEOS = new float[_nPoints / 2];
_table = new float[_nPoints];
for (int i = 0; i < _nPoints; i++)
_table[i] = sin(i * _radResolution);
// Table contains sin(2*pi*i/_nPoints) for 0<=i<_nPoints/4,
// followed by _nPoints/2<=i<3_nPoints/4
for (int i = 0; i < _nPoints / 4; i++)
_tableEOS[i] = sin(i * _radResolution);
for (int i = 0; i < _nPoints / 4; i++)
_tableEOS[_nPoints / 4 + i] = -_tableEOS[i];
}
float SineTable::at(int index) const {
assert((index >= 0) && (index < _nPoints));
return _table[index];
}
float SineTable::atLegacy(int index) const {
assert((index >= 0) && (index < _nPoints));
if (index < _refSize)
// [0,pi/2)
return _tableEOS[index];
if (index == _refSize)
// pi/2
return 1.0f; // sin(pi/2) = 1.0
if ((index > _refSize) && (index < 2 * _refSize))
// (pi/2,pi)
return _tableEOS[2 * _refSize - index];
if ((index >= 2 * _refSize) && (index < 3 * _refSize))
// [pi,3/2pi)
return -_tableEOS[index - 2 * _refSize];
if ((index > 3 * _refSize) && (index < _nPoints))
// (3/2pi,2pi)
return -_tableEOS[_nPoints - index];
return -1.0f; // sin(3pi/2) = -1.0
}
SineTable::~SineTable() {
delete[] _tableEOS;
delete[] _table;
}
} // End of namespace Math
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