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Diffstat (limited to 'common/fft.cpp')
| -rw-r--r-- | common/fft.cpp | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/common/fft.cpp b/common/fft.cpp new file mode 100644 index 0000000000..5852698b61 --- /dev/null +++ b/common/fft.cpp @@ -0,0 +1,243 @@ +/* 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' (I)FFT code which is in turn +// Based upon the (I)FFT code in FFmpeg +// Copyright (c) 2008 Loren Merritt +// Copyright (c) 2002 Fabrice Bellard +// Partly based on libdjbfft by D. J. Bernstein + +#include "common/cosinetables.h" +#include "common/fft.h" +#include "common/util.h" + +namespace Common { + +FFT::FFT(int bits, int inverse) : _bits(bits), _inverse(inverse) { + assert((_bits >= 2) && (_bits <= 16)); + + int n = 1 << bits; + + _tmpBuf = new Complex[n]; + _expTab = new Complex[n / 2]; + _revTab = new uint16[n]; + + _splitRadix = 1; + + for (int i = 0; i < n; i++) + _revTab[-splitRadixPermutation(i, n, _inverse) & (n - 1)] = i; +} + +FFT::~FFT() { + delete[] _revTab; + delete[] _expTab; + delete[] _tmpBuf; +} + +void FFT::permute(Complex *z) { + int np = 1 << _bits; + + if (_tmpBuf) { + for (int j = 0; j < np; j++) + _tmpBuf[_revTab[j]] = z[j]; + + memcpy(z, _tmpBuf, np * sizeof(Complex)); + + return; + } + + // Reverse + for (int j = 0; j < np; j++) { + int k = _revTab[j]; + + if (k < j) + SWAP(z[k], z[j]); + } +} + +int FFT::splitRadixPermutation(int i, int n, int inverse) { + if (n <= 2) + return i & 1; + + int m = n >> 1; + + if (!(i & m)) + return splitRadixPermutation(i, m, inverse) * 2; + + m >>= 1; + + if (inverse == !(i & m)) + return splitRadixPermutation(i, m, inverse) * 4 + 1; + + return splitRadixPermutation(i, m, inverse) * 4 - 1; +} + +#define sqrthalf (float)M_SQRT1_2 + +#define BF(x, y, a, b) { \ + x = a - b; \ + y = a + b; \ +} + +#define BUTTERFLIES(a0, a1, a2, a3) { \ + BF(t3, t5, t5, t1); \ + BF(a2.re, a0.re, a0.re, t5); \ + BF(a3.im, a1.im, a1.im, t3); \ + BF(t4, t6, t2, t6); \ + BF(a3.re, a1.re, a1.re, t4); \ + BF(a2.im, a0.im, a0.im, t6); \ +} + +// force loading all the inputs before storing any. +// this is slightly slower for small data, but avoids store->load aliasing +// for addresses separated by large powers of 2. +#define BUTTERFLIES_BIG(a0, a1, a2, a3) { \ + float r0 = a0.re, i0 = a0.im, r1 = a1.re, i1 = a1.im; \ + BF(t3, t5, t5, t1); \ + BF(a2.re, a0.re, r0, t5); \ + BF(a3.im, a1.im, i1, t3); \ + BF(t4, t6, t2, t6); \ + BF(a3.re, a1.re, r1, t4); \ + BF(a2.im, a0.im, i0, t6); \ +} + +#define TRANSFORM(a0, a1, a2, a3, wre, wim) { \ + t1 = a2.re * wre + a2.im * wim; \ + t2 = a2.im * wre - a2.re * wim; \ + t5 = a3.re * wre - a3.im * wim; \ + t6 = a3.im * wre + a3.re * wim; \ + BUTTERFLIES(a0, a1, a2, a3) \ +} + +#define TRANSFORM_ZERO(a0, a1, a2, a3) { \ + t1 = a2.re; \ + t2 = a2.im; \ + t5 = a3.re; \ + t6 = a3.im; \ + BUTTERFLIES(a0, a1, a2, a3) \ +} + +/* z[0...8n-1], w[1...2n-1] */ +#define PASS(name) \ +static void name(Complex *z, const float *wre, unsigned int n) { \ + float t1, t2, t3, t4, t5, t6; \ + int o1 = 2 * n; \ + int o2 = 4 * n; \ + int o3 = 6 * n; \ + const float *wim = wre + o1; \ + n--; \ + \ + TRANSFORM_ZERO(z[0], z[o1], z[o2], z[o3]); \ + TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]); \ + do { \ + z += 2; \ + wre += 2; \ + wim -= 2; \ + TRANSFORM(z[0], z[o1], z[o2], z[o3], wre[0], wim[0]);\ + TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);\ + } while(--n);\ +} + +PASS(pass) +#undef BUTTERFLIES +#define BUTTERFLIES BUTTERFLIES_BIG +PASS(pass_big) + +#define DECL_FFT(t, n, n2, n4) \ +static void fft##n(Complex *z) { \ + fft##n2(z); \ + fft##n4(z + n4 * 2); \ + fft##n4(z + n4 * 3); \ + pass(z, getCosineTable(t), n4 / 2);\ +} + +static void fft4(Complex *z) { + float t1, t2, t3, t4, t5, t6, t7, t8; + + BF(t3, t1, z[0].re, z[1].re); + BF(t8, t6, z[3].re, z[2].re); + BF(z[2].re, z[0].re, t1, t6); + BF(t4, t2, z[0].im, z[1].im); + BF(t7, t5, z[2].im, z[3].im); + BF(z[3].im, z[1].im, t4, t8); + BF(z[3].re, z[1].re, t3, t7); + BF(z[2].im, z[0].im, t2, t5); +} + +static void fft8(Complex *z) { + float t1, t2, t3, t4, t5, t6, t7, t8; + + fft4(z); + + BF(t1, z[5].re, z[4].re, -z[5].re); + BF(t2, z[5].im, z[4].im, -z[5].im); + BF(t3, z[7].re, z[6].re, -z[7].re); + BF(t4, z[7].im, z[6].im, -z[7].im); + BF(t8, t1, t3, t1); + BF(t7, t2, t2, t4); + BF(z[4].re, z[0].re, z[0].re, t1); + BF(z[4].im, z[0].im, z[0].im, t2); + BF(z[6].re, z[2].re, z[2].re, t7); + BF(z[6].im, z[2].im, z[2].im, t8); + + TRANSFORM(z[1], z[3], z[5], z[7], sqrthalf, sqrthalf); +} + +static void fft16(Complex *z) { + float t1, t2, t3, t4, t5, t6; + + fft8(z); + fft4(z + 8); + fft4(z + 12); + + const float * const cosTable = getCosineTable(4); + + TRANSFORM_ZERO(z[0], z[4], z[8], z[12]); + TRANSFORM(z[2], z[6], z[10], z[14], sqrthalf, sqrthalf); + TRANSFORM(z[1], z[5], z[9], z[13], cosTable[1],cosTable[3]); + TRANSFORM(z[3], z[7], z[11], z[15], cosTable[3], cosTable[1]); +} + +DECL_FFT(5, 32, 16, 8) +DECL_FFT(6, 64, 32, 16) +DECL_FFT(7, 128, 64, 32) +DECL_FFT(8, 256, 128, 64) +DECL_FFT(9, 512, 256, 128) +#define pass pass_big +DECL_FFT(10, 1024, 512, 256) +DECL_FFT(11, 2048, 1024, 512) +DECL_FFT(12, 4096, 2048, 1024) +DECL_FFT(13, 8192, 4096, 2048) +DECL_FFT(14, 16384, 8192, 4096) +DECL_FFT(15, 32768, 16384, 8192) +DECL_FFT(16, 65536, 32768, 16384) + +static void (* const fft_dispatch[])(Complex*) = { + fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024, + fft2048, fft4096, fft8192, fft16384, fft32768, fft65536, +}; + +void FFT::calc(Complex *z) { + fft_dispatch[_bits - 2](z); +} + +} // End of namespace Common |