Added qFastSin() and qFastCos() functions.

The new functions use a lookup table.

Reviewed-by: Trond

3 files changed, 333 insertions, 2 deletions

diff --git a/src/corelib/kernel/kernel.pri b/src/corelib/kernel/kernel.pri
index 003693b6a2..d0dad4907e 100644
--- a/src/corelib/kernel/kernel.pri
+++ b/src/corelib/kernel/kernel.pri
@@ -33,7 +33,8 @@ HEADERS += \
         kernel/qsystemsemaphore.h \
         kernel/qsystemsemaphore_p.h \
         kernel/qfunctions_p.h \
-        kernel/qguard_p.h
+        kernel/qguard_p.h \
+        kernel/qmath.h
 
 SOURCES += \
 	kernel/qabstracteventdispatcher.cpp \
@@ -55,7 +56,8 @@ SOURCES += \
         kernel/qcoreglobaldata.cpp \
         kernel/qsharedmemory.cpp \
         kernel/qsystemsemaphore.cpp \
-        kernel/qpointer.cpp 
+        kernel/qpointer.cpp \
+        kernel/qmath.cpp
 
 win32 {
 	SOURCES += \
diff --git a/src/corelib/kernel/qmath.cpp b/src/corelib/kernel/qmath.cpp
new file mode 100644
index 0000000000..24bec4a76e
--- /dev/null
+++ b/src/corelib/kernel/qmath.cpp
@@ -0,0 +1,305 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/qmath.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_CORE_EXPORT const qreal qt_sine_table[QT_SINE_TABLE_SIZE] = {
+    0.0,
+	0.024541228522912288,
+	0.049067674327418015,
+	0.073564563599667426,
+	0.098017140329560604,
+	0.1224106751992162,
+	0.14673047445536175,
+	0.17096188876030122,
+	0.19509032201612825,
+	0.2191012401568698,
+	0.24298017990326387,
+	0.26671275747489837,
+	0.29028467725446233,
+	0.31368174039889152,
+	0.33688985339222005,
+	0.35989503653498811,
+	0.38268343236508978,
+	0.40524131400498986,
+	0.42755509343028208,
+	0.44961132965460654,
+	0.47139673682599764,
+	0.49289819222978404,
+	0.51410274419322166,
+	0.53499761988709715,
+	0.55557023301960218,
+	0.57580819141784534,
+	0.59569930449243336,
+	0.61523159058062682,
+	0.63439328416364549,
+	0.65317284295377676,
+	0.67155895484701833,
+	0.68954054473706683,
+	0.70710678118654746,
+	0.72424708295146689,
+	0.74095112535495911,
+	0.75720884650648446,
+	0.77301045336273699,
+	0.78834642762660623,
+	0.80320753148064483,
+	0.81758481315158371,
+	0.83146961230254524,
+	0.84485356524970701,
+    0.85772861000027212,
+	0.87008699110871135,
+	0.88192126434835494,
+	0.89322430119551532,
+	0.90398929312344334,
+	0.91420975570353069,
+	0.92387953251128674,
+	0.93299279883473885,
+	0.94154406518302081,
+	0.94952818059303667,
+	0.95694033573220894,
+	0.96377606579543984,
+	0.97003125319454397,
+	0.97570213003852857,
+	0.98078528040323043,
+	0.98527764238894122,
+	0.98917650996478101,
+	0.99247953459870997,
+	0.99518472667219682,
+	0.99729045667869021,
+	0.99879545620517241,
+	0.99969881869620425,
+	1.0,
+	0.99969881869620425,
+	0.99879545620517241,
+	0.99729045667869021,
+	0.99518472667219693,
+	0.99247953459870997,
+	0.98917650996478101,
+	0.98527764238894122,
+	0.98078528040323043,
+	0.97570213003852857,
+	0.97003125319454397,
+	0.96377606579543984,
+	0.95694033573220894,
+	0.94952818059303667,
+	0.94154406518302081,
+	0.93299279883473885,
+	0.92387953251128674,
+	0.91420975570353069,
+	0.90398929312344345,
+	0.89322430119551521,
+	0.88192126434835505,
+	0.87008699110871146,
+	0.85772861000027212,
+	0.84485356524970723,
+	0.83146961230254546,
+	0.81758481315158371,
+	0.80320753148064494,
+	0.78834642762660634,
+	0.7730104533627371,
+	0.75720884650648468,
+	0.74095112535495899,
+	0.72424708295146689,
+	0.70710678118654757,
+	0.68954054473706705,
+	0.67155895484701855,
+	0.65317284295377664,
+	0.63439328416364549,
+	0.61523159058062693,
+	0.59569930449243347,
+	0.57580819141784545,
+	0.55557023301960218,
+	0.53499761988709715,
+	0.51410274419322177,
+	0.49289819222978415,
+	0.47139673682599786,
+	0.44961132965460687,
+	0.42755509343028203,
+	0.40524131400498992,
+	0.38268343236508989,
+	0.35989503653498833,
+	0.33688985339222033,
+	0.31368174039889141,
+	0.29028467725446239,
+	0.26671275747489848,
+	0.24298017990326407,
+	0.21910124015687005,
+	0.19509032201612861,
+	0.17096188876030122,
+	0.1467304744553618,
+	0.12241067519921635,
+	0.098017140329560826,
+	0.073564563599667732,
+	0.049067674327417966,
+	0.024541228522912326,
+	0.0,
+	-0.02454122852291208,
+	-0.049067674327417724,
+	-0.073564563599667496,
+	-0.09801714032956059,
+	-0.1224106751992161,
+	-0.14673047445536158,
+	-0.17096188876030097,
+	-0.19509032201612836,
+	-0.2191012401568698,
+	-0.24298017990326382,
+	-0.26671275747489825,
+	-0.29028467725446211,
+	-0.31368174039889118,
+	-0.33688985339222011,
+	-0.35989503653498811,
+	-0.38268343236508967,
+	-0.40524131400498969,
+	-0.42755509343028181,
+	-0.44961132965460665,
+	-0.47139673682599764,
+	-0.49289819222978393,
+	-0.51410274419322155,
+	-0.53499761988709693,
+	-0.55557023301960196,
+	-0.57580819141784534,
+	-0.59569930449243325,
+	-0.61523159058062671,
+	-0.63439328416364527,
+	-0.65317284295377653,
+	-0.67155895484701844,
+	-0.68954054473706683,
+	-0.70710678118654746,
+	-0.72424708295146678,
+	-0.74095112535495888,
+	-0.75720884650648423,
+	-0.77301045336273666,
+	-0.78834642762660589,
+	-0.80320753148064505,
+	-0.81758481315158382,
+	-0.83146961230254524,
+	-0.84485356524970701,
+	-0.85772861000027201,
+	-0.87008699110871135,
+	-0.88192126434835494,
+	-0.89322430119551521,
+	-0.90398929312344312,
+	-0.91420975570353047,
+	-0.92387953251128652,
+	-0.93299279883473896,
+	-0.94154406518302081,
+	-0.94952818059303667,
+	-0.95694033573220882,
+	-0.96377606579543984,
+	-0.97003125319454397,
+	-0.97570213003852846,
+	-0.98078528040323032,
+	-0.98527764238894111,
+	-0.9891765099647809,
+	-0.99247953459871008,
+	-0.99518472667219693,
+	-0.99729045667869021,
+	-0.99879545620517241,
+	-0.99969881869620425,
+	-1.0,
+	-0.99969881869620425,
+	-0.99879545620517241,
+	-0.99729045667869021,
+	-0.99518472667219693,
+	-0.99247953459871008,
+	-0.9891765099647809,
+	-0.98527764238894122,
+	-0.98078528040323043,
+	-0.97570213003852857,
+	-0.97003125319454397,
+	-0.96377606579543995,
+	-0.95694033573220894,
+	-0.94952818059303679,
+	-0.94154406518302092,
+	-0.93299279883473907,
+	-0.92387953251128663,
+	-0.91420975570353058,
+	-0.90398929312344334,
+	-0.89322430119551532,
+	-0.88192126434835505,
+	-0.87008699110871146,
+	-0.85772861000027223,
+	-0.84485356524970723,
+	-0.83146961230254546,
+	-0.81758481315158404,
+	-0.80320753148064528,
+	-0.78834642762660612,
+	-0.77301045336273688,
+	-0.75720884650648457,
+	-0.74095112535495911,
+	-0.724247082951467,
+	-0.70710678118654768,
+	-0.68954054473706716,
+	-0.67155895484701866,
+	-0.65317284295377709,
+	-0.63439328416364593,
+	-0.61523159058062737,
+	-0.59569930449243325,
+	-0.57580819141784523,
+	-0.55557023301960218,
+	-0.53499761988709726,
+	-0.51410274419322188,
+	-0.49289819222978426,
+	-0.47139673682599792,
+	-0.44961132965460698,
+	-0.42755509343028253,
+	-0.40524131400499042,
+	-0.38268343236509039,
+	-0.359895036534988,
+	-0.33688985339222,
+	-0.31368174039889152,
+	-0.2902846772544625,
+	-0.26671275747489859,
+	-0.24298017990326418,
+	-0.21910124015687016,
+	-0.19509032201612872,
+	-0.17096188876030177,
+	-0.14673047445536239,
+	-0.12241067519921603,
+	-0.098017140329560506,
+	-0.073564563599667412,
+	-0.049067674327418091,
+	-0.024541228522912448
+};
+
+QT_END_NAMESPACE
diff --git a/src/corelib/kernel/qmath.h b/src/corelib/kernel/qmath.h
index b5213232d1..a9e43789f1 100644
--- a/src/corelib/kernel/qmath.h
+++ b/src/corelib/kernel/qmath.h
@@ -52,6 +52,10 @@ QT_BEGIN_NAMESPACE
 
 QT_MODULE(Core)
 
+#define QT_SINE_TABLE_SIZE 256
+
+extern Q_CORE_EXPORT const qreal qt_sine_table[QT_SINE_TABLE_SIZE];
+
 inline int qCeil(qreal v)
 {
 #ifdef QT_USE_MATH_H_FLOATS
@@ -136,6 +140,26 @@ inline qreal qPow(qreal x, qreal y)
 #define M_PI (3.14159265358979323846)
 #endif
 
+inline qreal qFastSin(qreal x)
+{
+    int si = int(x * (0.5 * QT_SINE_TABLE_SIZE / M_PI)); // Would be more accurate with qRound, but slower.
+    qreal d = x - si * (2.0 * M_PI / QT_SINE_TABLE_SIZE);
+    int ci = si + QT_SINE_TABLE_SIZE / 4;
+    si &= QT_SINE_TABLE_SIZE - 1;
+    ci &= QT_SINE_TABLE_SIZE - 1;
+    return qt_sine_table[si] + (qt_sine_table[ci] - 0.5 * qt_sine_table[si] * d) * d;
+}
+
+inline qreal qFastCos(qreal x)
+{
+    int ci = int(x * (0.5 * QT_SINE_TABLE_SIZE / M_PI)); // Would be more accurate with qRound, but slower.
+    qreal d = x - ci * (2.0 * M_PI / QT_SINE_TABLE_SIZE);
+    int si = ci + QT_SINE_TABLE_SIZE / 4;
+    si &= QT_SINE_TABLE_SIZE - 1;
+    ci &= QT_SINE_TABLE_SIZE - 1;
+    return qt_sine_table[si] - (qt_sine_table[ci] + 0.5 * qt_sine_table[si] * d) * d;
+}
+
 QT_END_NAMESPACE
 
 QT_END_HEADER