COMMON: Add DCT math code
Based on eos' code which is based on FFmpeg's code
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Matthew Hoops
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210
common/dct.cpp
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210
common/dct.cpp
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/* 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)DCT code in FFmpeg
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// Copyright (c) 2009 Peter Ross <pross@xvid.org>
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// Copyright (c) 2010 Alex Converse <alex.converse@gmail.com>
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// Copyright (c) 2010 Vitor Sessak
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#include "common/dct.h"
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namespace Common {
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DCT::DCT(int bits, TransformType trans) : _bits(bits), _trans(trans), _rdft(0) {
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int n = 1 << _bits;
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_tCos = getCosineTable(_bits + 2);
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_csc2 = new float[n / 2];
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_rdft = new RDFT(_bits, (_trans == DCT_III) ? RDFT::IDFT_C2R : RDFT::DFT_R2C);
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for (int i = 0; i < (n / 2); i++)
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_csc2[i] = 0.5 / sin((M_PI / (2 * n) * (2 * i + 1)));
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}
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DCT::~DCT() {
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delete _rdft;
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delete[] _csc2;
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}
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void DCT::calc(float *data) {
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switch (_trans) {
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case DCT_I:
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calcDCTI(data);
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break;
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case DCT_II:
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calcDCTII(data);
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break;
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case DCT_III:
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calcDCTIII(data);
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break;
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case DST_I:
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calcDSTI(data);
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break;
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}
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}
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/* sin((M_PI * x / (2*n)) */
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#define SIN(n,x) (_tCos[(n) - (x)])
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/* cos((M_PI * x / (2*n)) */
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#define COS(n,x) (_tCos[x])
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void DCT::calcDCTI(float *data) {
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int n = 1 << _bits;
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float next = -0.5 * (data[0] - data[n]);
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for (int i = 0; i < (n / 2); i++) {
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float tmp1 = data[i ];
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float tmp2 = data[n - i];
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float s = SIN(n, 2 * i);
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float c = COS(n, 2 * i);
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c *= tmp1 - tmp2;
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s *= tmp1 - tmp2;
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next += c;
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tmp1 = (tmp1 + tmp2) * 0.5;
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data[i ] = tmp1 - s;
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data[n - i] = tmp1 + s;
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}
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_rdft->calc(data);
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data[n] = data[1];
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data[1] = next;
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for (int i = 3; i <= n; i += 2)
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data[i] = data[i - 2] - data[i];
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}
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void DCT::calcDCTII(float *data) {
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int n = 1 << _bits;
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for (int i = 0; i < (n / 2); i++) {
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float tmp1 = data[i ];
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float tmp2 = data[n - i - 1];
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float s = SIN(n, 2 * i + 1);
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s *= tmp1 - tmp2;
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tmp1 = (tmp1 + tmp2) * 0.5;
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data[i ] = tmp1 + s;
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data[n-i-1] = tmp1 - s;
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}
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_rdft->calc(data);
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float next = data[1] * 0.5;
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data[1] *= -1;
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for (int i = n - 2; i >= 0; i -= 2) {
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float inr = data[i ];
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float ini = data[i + 1];
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float c = COS(n, i);
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float s = SIN(n, i);
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data[i ] = c * inr + s * ini;
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data[i+1] = next;
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next += s * inr - c * ini;
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}
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}
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void DCT::calcDCTIII(float *data) {
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int n = 1 << _bits;
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float next = data[n - 1];
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float inv_n = 1.0 / n;
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for (int i = n - 2; i >= 2; i -= 2) {
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float val1 = data[i ];
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float val2 = data[i - 1] - data[i + 1];
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float c = COS(n, i);
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float s = SIN(n, i);
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data[i ] = c * val1 + s * val2;
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data[i + 1] = s * val1 - c * val2;
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}
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data[1] = 2 * next;
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_rdft->calc(data);
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for (int i = 0; i < (n / 2); i++) {
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float tmp1 = data[i ] * inv_n;
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float tmp2 = data[n - i - 1] * inv_n;
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float csc = _csc2[i] * (tmp1 - tmp2);
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tmp1 += tmp2;
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data[i ] = tmp1 + csc;
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data[n - i - 1] = tmp1 - csc;
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}
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}
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void DCT::calcDSTI(float *data) {
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int n = 1 << _bits;
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data[0] = 0;
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for (int i = 1; i < (n / 2); i++) {
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float tmp1 = data[i ];
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float tmp2 = data[n - i];
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float s = SIN(n, 2 * i);
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s *= tmp1 + tmp2;
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tmp1 = (tmp1 - tmp2) * 0.5;
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data[i ] = s + tmp1;
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data[n - i] = s - tmp1;
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}
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data[n / 2] *= 2;
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_rdft->calc(data);
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data[0] *= 0.5;
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for (int i = 1; i < (n - 2); i += 2) {
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data[i + 1] += data[i - 1];
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data[i ] = -data[i + 2];
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}
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data[n - 1] = 0;
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}
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} // End of namespace Common
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71
common/dct.h
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71
common/dct.h
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@ -0,0 +1,71 @@
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/* 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)DCT code in FFmpeg
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// Copyright (c) 2009 Peter Ross <pross@xvid.org>
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// Copyright (c) 2010 Alex Converse <alex.converse@gmail.com>
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// Copyright (c) 2010 Vitor Sessak
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#ifndef COMMON_DCT_H
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#define COMMON_DCT_H
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#include "common/scummsys.h"
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#include "common/math.h"
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#include "common/rdft.h"
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namespace Common {
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/** (Inverse) Discrete Cosine Transforms. */
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class DCT {
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public:
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enum TransformType {
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DCT_II,
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DCT_III,
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DCT_I,
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DST_I
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};
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DCT(int bits, TransformType trans);
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~DCT();
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void calc(float *data);
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private:
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int _bits;
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TransformType _trans;
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const float *_tCos;
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float *_csc2;
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RDFT *_rdft;
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void calcDCTI (float *data);
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void calcDCTII (float *data);
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void calcDCTIII(float *data);
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void calcDSTI (float *data);
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};
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} // End of namespace Common
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#endif // COMMON_DCT_H
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@ -6,6 +6,7 @@ MODULE_OBJS := \
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config-file.o \
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config-manager.o \
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dcl.o \
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dct.o \
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debug.o \
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error.o \
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EventDispatcher.o \
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