mirror of
https://github.com/libretro/scummvm.git
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260 lines
6.0 KiB
C++
260 lines
6.0 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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*
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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' (I)FFT code which is in turn
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// Based upon the (I)FFT code in FFmpeg
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// Copyright (c) 2008 Loren Merritt
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// Copyright (c) 2002 Fabrice Bellard
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// Partly based on libdjbfft by D. J. Bernstein
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#include "common/cosinetables.h"
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#include "common/fft.h"
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#include "common/util.h"
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#include "common/textconsole.h"
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namespace Common {
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FFT::FFT(int bits, int inverse) : _bits(bits), _inverse(inverse) {
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assert((_bits >= 2) && (_bits <= 16));
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int n = 1 << bits;
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int nPoints;
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_tmpBuf = new Complex[n];
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_expTab = new Complex[n / 2];
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_revTab = new uint16[n];
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_splitRadix = 1;
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for (int i = 0; i < n; i++)
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_revTab[-splitRadixPermutation(i, n, _inverse) & (n - 1)] = i;
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for (int i = 0; i < ARRAYSIZE(_cosTables); i++) {
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if (i + 4 <= _bits) {
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nPoints = 1 << (i + 4);
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_cosTables[i] = new Common::CosineTable(nPoints);
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}
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else
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_cosTables[i] = nullptr;
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}
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}
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FFT::~FFT() {
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for (int i = 0; i < ARRAYSIZE(_cosTables); i++) {
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delete _cosTables[i];
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}
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delete[] _revTab;
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delete[] _expTab;
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delete[] _tmpBuf;
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}
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const uint16 *FFT::getRevTab() const {
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return _revTab;
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}
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void FFT::permute(Complex *z) {
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int np = 1 << _bits;
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if (_tmpBuf) {
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for (int j = 0; j < np; j++)
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_tmpBuf[_revTab[j]] = z[j];
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memcpy(z, _tmpBuf, np * sizeof(Complex));
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return;
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}
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// Reverse
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for (int j = 0; j < np; j++) {
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int k = _revTab[j];
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if (k < j)
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SWAP(z[k], z[j]);
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}
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}
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int FFT::splitRadixPermutation(int i, int n, int inverse) {
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if (n <= 2)
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return i & 1;
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int m = n >> 1;
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if (!(i & m))
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return splitRadixPermutation(i, m, inverse) * 2;
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m >>= 1;
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if (inverse == !(i & m))
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return splitRadixPermutation(i, m, inverse) * 4 + 1;
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return splitRadixPermutation(i, m, inverse) * 4 - 1;
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}
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#define sqrthalf (float)M_SQRT1_2
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#define BF(x, y, a, b) { \
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x = a - b; \
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y = a + b; \
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}
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#define BUTTERFLIES(a0, a1, a2, a3) { \
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BF(t3, t5, t5, t1); \
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BF(a2.re, a0.re, a0.re, t5); \
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BF(a3.im, a1.im, a1.im, t3); \
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BF(t4, t6, t2, t6); \
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BF(a3.re, a1.re, a1.re, t4); \
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BF(a2.im, a0.im, a0.im, t6); \
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}
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// force loading all the inputs before storing any.
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// this is slightly slower for small data, but avoids store->load aliasing
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// for addresses separated by large powers of 2.
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#define BUTTERFLIES_BIG(a0, a1, a2, a3) { \
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float r0 = a0.re, i0 = a0.im, r1 = a1.re, i1 = a1.im; \
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BF(t3, t5, t5, t1); \
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BF(a2.re, a0.re, r0, t5); \
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BF(a3.im, a1.im, i1, t3); \
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BF(t4, t6, t2, t6); \
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BF(a3.re, a1.re, r1, t4); \
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BF(a2.im, a0.im, i0, t6); \
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}
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#define TRANSFORM(a0, a1, a2, a3, wre, wim) { \
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t1 = a2.re * wre + a2.im * wim; \
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t2 = a2.im * wre - a2.re * wim; \
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t5 = a3.re * wre - a3.im * wim; \
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t6 = a3.im * wre + a3.re * wim; \
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BUTTERFLIES(a0, a1, a2, a3) \
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}
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#define TRANSFORM_ZERO(a0, a1, a2, a3) { \
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t1 = a2.re; \
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t2 = a2.im; \
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t5 = a3.re; \
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t6 = a3.im; \
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BUTTERFLIES(a0, a1, a2, a3) \
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}
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/* z[0...8n-1], w[1...2n-1] */
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#define PASS(name) \
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static void name(Complex *z, const float *wre, unsigned int n) { \
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float t1, t2, t3, t4, t5, t6; \
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int o1 = 2 * n; \
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int o2 = 4 * n; \
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int o3 = 6 * n; \
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const float *wim = wre + o1; \
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n--; \
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\
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TRANSFORM_ZERO(z[0], z[o1], z[o2], z[o3]); \
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TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]); \
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do { \
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z += 2; \
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wre += 2; \
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wim -= 2; \
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TRANSFORM(z[0], z[o1], z[o2], z[o3], wre[0], wim[0]);\
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TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);\
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} while(--n);\
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}
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PASS(pass)
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#undef BUTTERFLIES
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#define BUTTERFLIES BUTTERFLIES_BIG
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PASS(pass_big)
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void FFT::fft4(Complex *z) {
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float t1, t2, t3, t4, t5, t6, t7, t8;
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BF(t3, t1, z[0].re, z[1].re);
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BF(t8, t6, z[3].re, z[2].re);
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BF(z[2].re, z[0].re, t1, t6);
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BF(t4, t2, z[0].im, z[1].im);
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BF(t7, t5, z[2].im, z[3].im);
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BF(z[3].im, z[1].im, t4, t8);
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BF(z[3].re, z[1].re, t3, t7);
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BF(z[2].im, z[0].im, t2, t5);
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}
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void FFT::fft8(Complex *z) {
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float t1, t2, t3, t4, t5, t6, t7, t8;
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fft4(z);
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BF(t1, z[5].re, z[4].re, -z[5].re);
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BF(t2, z[5].im, z[4].im, -z[5].im);
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BF(t3, z[7].re, z[6].re, -z[7].re);
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BF(t4, z[7].im, z[6].im, -z[7].im);
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BF(t8, t1, t3, t1);
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BF(t7, t2, t2, t4);
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BF(z[4].re, z[0].re, z[0].re, t1);
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BF(z[4].im, z[0].im, z[0].im, t2);
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BF(z[6].re, z[2].re, z[2].re, t7);
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BF(z[6].im, z[2].im, z[2].im, t8);
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TRANSFORM(z[1], z[3], z[5], z[7], sqrthalf, sqrthalf);
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}
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void FFT::fft16(Complex *z) {
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float t1, t2, t3, t4, t5, t6;
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fft8(z);
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fft4(z + 8);
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fft4(z + 12);
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assert(_cosTables[0]);
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const float * const cosTable = _cosTables[0]->getTable();
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TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
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TRANSFORM(z[2], z[6], z[10], z[14], sqrthalf, sqrthalf);
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TRANSFORM(z[1], z[5], z[9], z[13], cosTable[1],cosTable[3]);
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TRANSFORM(z[3], z[7], z[11], z[15], cosTable[3], cosTable[1]);
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}
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void FFT::fft(int n, int logn, Complex *z) {
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switch (logn) {
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case 2:
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fft4(z);
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break;
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case 3:
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fft8(z);
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break;
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case 4:
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fft16(z);
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break;
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default:
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fft((n / 2), logn - 1, z);
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fft((n / 4), logn - 2, z + (n / 4) * 2);
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fft((n / 4), logn - 2, z + (n / 4) * 3);
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assert(_cosTables[logn - 4]);
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if (n > 1024)
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pass_big(z, _cosTables[logn - 4]->getTable(), (n / 4) / 2);
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else
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pass(z, _cosTables[logn - 4]->getTable(), (n / 4) / 2);
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}
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}
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void FFT::calc(Complex *z) {
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fft(1 << _bits, _bits, z);
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}
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} // End of namespace Common
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