COMMON: Add an FFT math handler

Based on eos' code which is based on FFmpeg's code

3 files changed, 319 insertions, 0 deletions

diff --git a/common/fft.cpp b/common/fft.cpp
new file mode 100644
index 0000000000..9398034c82
--- /dev/null
+++ b/common/fft.cpp
@@ -0,0 +1,245 @@
+/* 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/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(n,n2,n4)\
+static void fft##n(Complex *z)\
+{\
+	fft##n2(z);\
+	fft##n4(z+n4*2);\
+	fft##n4(z+n4*3);\
+	pass(z,cosTable##n,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);
+
+	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],cosTable16[1],cosTable16[3]);
+	TRANSFORM(z[3],z[7],z[11],z[15],cosTable16[3],cosTable16[1]);
+}
+
+DECL_FFT(32,16,8)
+DECL_FFT(64,32,16)
+DECL_FFT(128,64,32)
+DECL_FFT(256,128,64)
+DECL_FFT(512,256,128)
+#define pass pass_big
+DECL_FFT(1024,512,256)
+DECL_FFT(2048,1024,512)
+DECL_FFT(4096,2048,1024)
+DECL_FFT(8192,4096,2048)
+DECL_FFT(16384,8192,4096)
+DECL_FFT(32768,16384,8192)
+DECL_FFT(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
diff --git a/common/fft.h b/common/fft.h
new file mode 100644
index 0000000000..17d1ef0055
--- /dev/null
+++ b/common/fft.h
@@ -0,0 +1,73 @@
+/* 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
+
+#ifndef COMMON_FFT_H
+#define COMMON_FFT_H
+
+#include "common/scummsys.h"
+#include "common/math.h"
+
+namespace Common {
+
+/** (Inverse) Fast Fourier Transform. */
+class FFT {
+public:
+	FFT(int bits, int inverse);
+	~FFT();
+
+	/** Do the permutation needed BEFORE calling calc(). */
+	void permute(Complex *z);
+
+	/** Do a complex FFT.
+	 *
+	 *  The input data must be permuted before.
+	 *  No 1.0/sqrt(n) normalization is done.
+	 */
+	void calc(Complex *z);
+
+private:
+	int _bits;
+	int _inverse;
+
+	uint16 *_revTab;
+
+	Complex *_expTab;
+	Complex *_tmpBuf;
+
+	const float *_tSin;
+	const float *_tCos;
+
+	int _splitRadix;
+	int _permutation;
+
+	static int splitRadixPermutation(int i, int n, int inverse);
+};
+
+} // End of namespace Common
+
+#endif // COMMON_FFT_H
diff --git a/common/module.mk b/common/module.mk
index 7716f74d34..2ab4c113fa 100644
--- a/common/module.mk
+++ b/common/module.mk
@@ -10,6 +10,7 @@ MODULE_OBJS := \
 	error.o \
 	EventDispatcher.o \
 	EventRecorder.o \
+	fft.o \
 	file.o \
 	fs.o \
 	hashmap.o \