mirror of
https://github.com/libretro/scummvm.git
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f4ba8a6485
This removes the large static tables from the binary (which saves 500K to 1Mb of binary size) and replaced them with a class which generates the required tables as needed in RAM. This has been tested with QDM2 and shows no obvious performance degredation and Memprof shows no significant rise in RAM usage.
107 lines
3.0 KiB
C++
107 lines
3.0 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)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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#include "common/cosinetables.h"
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#include "common/sinetables.h"
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namespace Common {
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RDFT::RDFT(int bits, TransformType trans) : _bits(bits), _fft(0) {
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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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_sin = new SineTable(bits);
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_tSin = _sin->getTable() + (trans == DFT_R2C || trans == DFT_C2R) * (n >> 2);
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_cos = new CosineTable(bits);
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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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delete _sin;
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delete _cos;
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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 = 0.5;
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const float k2 = 0.5 - _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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