dither.cpp
Go to the documentation of this file.00001 /********************************************************************* 00002 * Software License Agreement (BSD License) 00003 * 00004 * Copyright (c) 2009, Willow Garage, Inc. 00005 * All rights reserved. 00006 * 00007 * Redistribution and use in source and binary forms, with or without 00008 * modification, are permitted provided that the following conditions 00009 * are met: 00010 * 00011 * * Redistributions of source code must retain the above copyright 00012 * notice, this list of conditions and the following disclaimer. 00013 * * Redistributions in binary form must reproduce the above 00014 * copyright notice, this list of conditions and the following 00015 * disclaimer in the documentation and/or other materials provided 00016 * with the distribution. 00017 * * Neither the name of the Willow Garage nor the names of its 00018 * contributors may be used to endorse or promote products derived 00019 * from this software without specific prior written permission. 00020 * 00021 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00024 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00025 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00026 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00027 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00028 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00029 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00030 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00031 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00032 * POSSIBILITY OF SUCH DAMAGE. 00033 *********************************************************************/ 00034 00035 // Original version: Kevin Watts <watts@willowgarage.com> 00036 00037 #include <control_toolbox/dither.h> 00038 00039 // Constants to generate white noise 00040 #define M 714025 00041 #define IA 1366 00042 #define IC 150889 00043 #define LM 2147483647 00044 #define LAM (1.0/LM) 00045 #define LA 16807 00046 #define LR 2836 00047 #define LQ 127773 00048 00049 00050 namespace control_toolbox { 00051 00052 Dither::Dither() : amplitude_(0), s_(0), x_(0), idum((long)0) 00053 { 00054 00055 } 00056 00057 Dither::~Dither() 00058 { 00059 } 00060 00061 double Dither::update() 00062 { 00063 // Shamelessly copied from 00064 // http://www.koders.com/cpp/fidB74E9B684392743A5D3DE72227863382884AB0A2.aspx?s=Chebyshev 00065 00066 double fac, r, v1, v2; 00067 00068 if (s_ == 0) 00069 { 00070 for (int i = 0; i < 100; i++) 00071 { 00072 v1 = (2.0 * uni()) - 1.0; 00073 v2 = (2.0 * uni()) - 1.0; 00074 r = (v1 * v1) + (v2 * v2); 00075 00076 if (r < 1.0) 00077 break; 00078 } 00079 if (r >= 1.0) 00080 r = 1.0; 00081 00082 fac = sqrt(-2.0 * log(r) / r); 00083 x_ = v1 * fac; 00084 s_ = 1; 00085 return v2 * fac * amplitude_; 00086 } 00087 else 00088 { 00089 s_ = 0; 00090 return x_ * amplitude_; 00091 } 00092 } 00093 00094 00095 //-------------------------------------------------------------------- 00096 // Returns uniform deviate between 0.0 and 1.0. 00097 // Used to generate PN data 00098 //--------------------------------------------------------------------- 00099 double Dither::uni() 00100 { 00101 double rm, r1; 00102 rm = 1./M; 00103 idum = (long)fmod(IA * idum + IC, M); 00104 r1 = idum * rm; 00105 return(r1); 00106 } 00107 00108 00109 }