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https://github.com/DSheirer/sdrtrunk.git
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39f6d6c831
* Misc minor performance improvements * Use more concise loop syntax * Use more concise Collection sort syntax * Use StringUtils pad methods * Optimize some loops and double-map-lookups * Optimize array instantiation There are two styles to convert a collection to an array: either using a pre-sized array (like c.toArray(new String[c.size()])) or using an empty array (like c.toArray(new String[0]). In older Java versions using pre-sized array was recommended, as the reflection call which is necessary to create an array of proper size was quite slow. However since late updates of OpenJDK 6 this call was intrinsified, making the performance of the empty array version the same and sometimes even better, compared to the pre-sized version. Also passing pre-sized array is dangerous for a concurrent or synchronized collection as a data race is possible between the size and toArray call which may result in extra nulls at the end of the array, if the collection was concurrently shrunk during the operation. * Cleanup string concatenation * Use EnumMap where possible * Use FastMath instead of Math * Initialize complex things only once * Reduce method size to aloow more JIT inlining * remove map of short->float * Move field to local variable * Cleanup Map lookup Co-authored-by: Rob Ekl <xwq876@zebra.com>
264 lines
9.1 KiB
Java
264 lines
9.1 KiB
Java
/*******************************************************************************
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* SDR Trunk
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* Copyright (C) 2014 Dennis Sheirer
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (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, see <http://www.gnu.org/licenses/>
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*
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* ----------------------------------------------
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* Adapted from GNU Radio's gr_fast_atan2f() method, retrieved Jan 2013 from
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* https://raw.github.com/gnuradio/gnuradio/master/gnuradio-core/src/lib/general/gr_fast_atan2f.cc
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*
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* Copyright 2005 Free Software Foundation, Inc.
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*
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* This file is part of GNU Radio
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*
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* GNU Radio is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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package io.github.dsheirer.util;
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import io.github.dsheirer.sample.complex.Complex;
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import org.apache.commons.math3.util.FastMath;
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public class ArcTangent
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{
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public static final double sTANGENT_MAP_RESOLUTION = 0.003921549;
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public static final double sRADIANS_PER_DEGREE = 0.017453293;
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public static final int sTANGENT_MAP_SIZE = 256;
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public static final double sHALF_PI = FastMath.PI / 2;
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//ArcTangents from 0 to pi/4 radians
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private static double[] sLOOKUP_TABLE = new double[] {
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0.000000e+00, 3.921549e-03, 7.842976e-03, 1.176416e-02,
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1.568499e-02, 1.960533e-02, 2.352507e-02, 2.744409e-02,
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3.136226e-02, 3.527947e-02, 3.919560e-02, 4.311053e-02,
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4.702413e-02, 5.093629e-02, 5.484690e-02, 5.875582e-02,
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6.266295e-02, 6.656816e-02, 7.047134e-02, 7.437238e-02,
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7.827114e-02, 8.216752e-02, 8.606141e-02, 8.995267e-02,
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9.384121e-02, 9.772691e-02, 1.016096e-01, 1.054893e-01,
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1.093658e-01, 1.132390e-01, 1.171087e-01, 1.209750e-01,
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1.248376e-01, 1.286965e-01, 1.325515e-01, 1.364026e-01,
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1.402496e-01, 1.440924e-01, 1.479310e-01, 1.517652e-01,
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1.555948e-01, 1.594199e-01, 1.632403e-01, 1.670559e-01,
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1.708665e-01, 1.746722e-01, 1.784728e-01, 1.822681e-01,
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1.860582e-01, 1.898428e-01, 1.936220e-01, 1.973956e-01,
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2.011634e-01, 2.049255e-01, 2.086818e-01, 2.124320e-01,
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2.161762e-01, 2.199143e-01, 2.236461e-01, 2.273716e-01,
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2.310907e-01, 2.348033e-01, 2.385093e-01, 2.422086e-01,
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2.459012e-01, 2.495869e-01, 2.532658e-01, 2.569376e-01,
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2.606024e-01, 2.642600e-01, 2.679104e-01, 2.715535e-01,
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2.751892e-01, 2.788175e-01, 2.824383e-01, 2.860514e-01,
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2.896569e-01, 2.932547e-01, 2.968447e-01, 3.004268e-01,
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3.040009e-01, 3.075671e-01, 3.111252e-01, 3.146752e-01,
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3.182170e-01, 3.217506e-01, 3.252758e-01, 3.287927e-01,
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3.323012e-01, 3.358012e-01, 3.392926e-01, 3.427755e-01,
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3.462497e-01, 3.497153e-01, 3.531721e-01, 3.566201e-01,
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3.600593e-01, 3.634896e-01, 3.669110e-01, 3.703234e-01,
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3.737268e-01, 3.771211e-01, 3.805064e-01, 3.838825e-01,
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3.872494e-01, 3.906070e-01, 3.939555e-01, 3.972946e-01,
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4.006244e-01, 4.039448e-01, 4.072558e-01, 4.105574e-01,
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4.138496e-01, 4.171322e-01, 4.204054e-01, 4.236689e-01,
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4.269229e-01, 4.301673e-01, 4.334021e-01, 4.366272e-01,
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4.398426e-01, 4.430483e-01, 4.462443e-01, 4.494306e-01,
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4.526070e-01, 4.557738e-01, 4.589307e-01, 4.620778e-01,
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4.652150e-01, 4.683424e-01, 4.714600e-01, 4.745676e-01,
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4.776654e-01, 4.807532e-01, 4.838312e-01, 4.868992e-01,
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4.899573e-01, 4.930055e-01, 4.960437e-01, 4.990719e-01,
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5.020902e-01, 5.050985e-01, 5.080968e-01, 5.110852e-01,
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5.140636e-01, 5.170320e-01, 5.199904e-01, 5.229388e-01,
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5.258772e-01, 5.288056e-01, 5.317241e-01, 5.346325e-01,
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5.375310e-01, 5.404195e-01, 5.432980e-01, 5.461666e-01,
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5.490251e-01, 5.518738e-01, 5.547124e-01, 5.575411e-01,
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5.603599e-01, 5.631687e-01, 5.659676e-01, 5.687566e-01,
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5.715357e-01, 5.743048e-01, 5.770641e-01, 5.798135e-01,
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5.825531e-01, 5.852828e-01, 5.880026e-01, 5.907126e-01,
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5.934128e-01, 5.961032e-01, 5.987839e-01, 6.014547e-01,
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6.041158e-01, 6.067672e-01, 6.094088e-01, 6.120407e-01,
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6.146630e-01, 6.172755e-01, 6.198784e-01, 6.224717e-01,
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6.250554e-01, 6.276294e-01, 6.301939e-01, 6.327488e-01,
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6.352942e-01, 6.378301e-01, 6.403565e-01, 6.428734e-01,
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6.453808e-01, 6.478788e-01, 6.503674e-01, 6.528466e-01,
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6.553165e-01, 6.577770e-01, 6.602282e-01, 6.626701e-01,
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6.651027e-01, 6.675261e-01, 6.699402e-01, 6.723452e-01,
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6.747409e-01, 6.771276e-01, 6.795051e-01, 6.818735e-01,
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6.842328e-01, 6.865831e-01, 6.889244e-01, 6.912567e-01,
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6.935800e-01, 6.958943e-01, 6.981998e-01, 7.004964e-01,
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7.027841e-01, 7.050630e-01, 7.073330e-01, 7.095943e-01,
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7.118469e-01, 7.140907e-01, 7.163258e-01, 7.185523e-01,
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7.207701e-01, 7.229794e-01, 7.251800e-01, 7.273721e-01,
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7.295557e-01, 7.317307e-01, 7.338974e-01, 7.360555e-01,
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7.382053e-01, 7.403467e-01, 7.424797e-01, 7.446045e-01,
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7.467209e-01, 7.488291e-01, 7.509291e-01, 7.530208e-01,
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7.551044e-01, 7.571798e-01, 7.592472e-01, 7.613064e-01,
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7.633576e-01, 7.654008e-01, 7.674360e-01, 7.694633e-01,
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7.714826e-01, 7.734940e-01, 7.754975e-01, 7.774932e-01,
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7.794811e-01, 7.814612e-01, 7.834335e-01, 7.853983e-01,
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7.853983e-01 };
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/**
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* Lookup radian angle from polar coordinates represented by the
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* ComplexSample
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*
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* @param sample representing polar coordinates
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* @return - angle in radians
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*/
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public static double getAngle( Complex sample )
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{
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return getAngle( ( (double) sample.inphase() ),
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( (double) sample.quadrature() ) );
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}
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/**
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* Lookup radian angle from polar coordinates x and y
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* @param x - x polar coordinate
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* @param y - y polar coordinate
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* @return - angle in radians
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*/
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public static double getAngle( double x, double y )
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{
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/**
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* Calculates the angle of the vector (x,y) based on a table lookup and
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* linear interpolation. The table uses a 256 point table covering
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* -45 to +45 degrees and uses symmetry to determine the final angle
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* value in the range of -180 to 180 degrees. Note that this function
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* uses the small angle approximation for values close to zero. This
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* routine calculates the arc tangent with an average error of
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* +/- 0.045 degrees.
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*/
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double alpha;
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double angle;
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double base_angle;
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int index;
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//Check for divide by zero
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if( x == 0.0 && y == 0.0 )
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{
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return 0.0;
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}
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//Normalize to +/- 45 degree range
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double x_abs = FastMath.abs( x );
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double y_abs = FastMath.abs( y );
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//Calculate the ratio ( opposite/adjacent )
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double z;
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if( x_abs < y_abs )
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{
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z = x_abs / y_abs;
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}
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else
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{
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z = y_abs / x_abs;
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}
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//When the ratio approaches table resolution, the angle is best
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//approximated with the argument itself
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if( z < sTANGENT_MAP_RESOLUTION )
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{
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base_angle = z;
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}
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else
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{
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alpha = z * (double)( sTANGENT_MAP_SIZE - .5 );
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index = (int)alpha;
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alpha -= (double)index;
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//Determine base angle based on quadrant and add or subtract table
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//value from base angle, based on quadrant
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base_angle = sLOOKUP_TABLE[ index ];
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base_angle += ( sLOOKUP_TABLE[ index + 1 ] -
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sLOOKUP_TABLE[ index ] ) * alpha;
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}
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//Map the angle to the correct quadrant
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if( x_abs > y_abs ) // -45 to 45, or 135 to -135
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{
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if( x >= 0.0 ) // -45 to 45
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{
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if( y >= 0.0 )
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{
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angle = base_angle; // 0 to 45
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}
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else
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{
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angle = -base_angle; // -45 to 0
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}
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}
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else // 135 to 180 or -180 to -135
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{
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angle = FastMath.PI;
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if( y >= 0.0 )
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{
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angle -= base_angle; // 135 to 180
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}
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else
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{
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angle = base_angle - angle; // 180 to -135
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}
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}
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}
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else // 45 to 135, or -135 to -45
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{
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if( y >= 0.0 ) //45 to 135
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{
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angle = sHALF_PI;
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if( x >= 0.0 )
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{
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angle -= base_angle; // 45 to 90
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}
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else
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{
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angle += base_angle; // 90 to 135
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}
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}
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else
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{
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angle = -sHALF_PI;
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if( x >= 0.0 )
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{
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angle += base_angle; //-90 to -45
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}
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else
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{
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angle -= base_angle; //-135 to -90
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}
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}
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}
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// //Check for negative radian angle value
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//
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// if( angle < 0 )
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// {
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// angle += 2 * Math.PI;
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// }
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return angle;
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}
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}
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