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<h1>gr_math.h</h1> </div>
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<div class="contents">
<a href="gr__math_8h.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* -*- c++ -*- */</span>
<a name="l00002"></a>00002 <span class="comment">/*</span>
<a name="l00003"></a>00003 <span class="comment"> * Copyright 2003,2005,2008 Free Software Foundation, Inc.</span>
<a name="l00004"></a>00004 <span class="comment"> * </span>
<a name="l00005"></a>00005 <span class="comment"> * This file is part of GNU Radio</span>
<a name="l00006"></a>00006 <span class="comment"> * </span>
<a name="l00007"></a>00007 <span class="comment"> * GNU Radio is free software; you can redistribute it and/or modify</span>
<a name="l00008"></a>00008 <span class="comment"> * it under the terms of the GNU General Public License as published by</span>
<a name="l00009"></a>00009 <span class="comment"> * the Free Software Foundation; either version 3, or (at your option)</span>
<a name="l00010"></a>00010 <span class="comment"> * any later version.</span>
<a name="l00011"></a>00011 <span class="comment"> * </span>
<a name="l00012"></a>00012 <span class="comment"> * GNU Radio is distributed in the hope that it will be useful,</span>
<a name="l00013"></a>00013 <span class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<a name="l00014"></a>00014 <span class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span>
<a name="l00015"></a>00015 <span class="comment"> * GNU General Public License for more details.</span>
<a name="l00016"></a>00016 <span class="comment"> * </span>
<a name="l00017"></a>00017 <span class="comment"> * You should have received a copy of the GNU General Public License</span>
<a name="l00018"></a>00018 <span class="comment"> * along with GNU Radio; see the file COPYING. If not, write to</span>
<a name="l00019"></a>00019 <span class="comment"> * the Free Software Foundation, Inc., 51 Franklin Street,</span>
<a name="l00020"></a>00020 <span class="comment"> * Boston, MA 02110-1301, USA.</span>
<a name="l00021"></a>00021 <span class="comment"> */</span>
<a name="l00022"></a>00022
<a name="l00023"></a>00023 <span class="comment">/*</span>
<a name="l00024"></a>00024 <span class="comment"> * mathematical odds and ends.</span>
<a name="l00025"></a>00025 <span class="comment"> */</span>
<a name="l00026"></a>00026
<a name="l00027"></a>00027 <span class="preprocessor">#ifndef _GR_MATH_H_</span>
<a name="l00028"></a>00028 <span class="preprocessor"></span><span class="preprocessor">#define _GR_MATH_H_</span>
<a name="l00029"></a>00029 <span class="preprocessor"></span>
<a name="l00030"></a>00030 <span class="preprocessor">#include <gr_complex.h></span>
<a name="l00031"></a>00031
<a name="l00032"></a>00032 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">bool</span>
<a name="l00033"></a><a class="code" href="gr__math_8h.html#ace69f572707e22fad277c8fe774de2bb">00033</a> <a class="code" href="gr__math_8h.html#ace69f572707e22fad277c8fe774de2bb">gr_is_power_of_2</a>(<span class="keywordtype">long</span> x)
<a name="l00034"></a>00034 {
<a name="l00035"></a>00035 <span class="keywordflow">return</span> x != 0 && (x & (x-1)) == 0;
<a name="l00036"></a>00036 }
<a name="l00037"></a>00037
<a name="l00038"></a>00038 <span class="keywordtype">long</span> <a class="code" href="gr__math_8h.html#a7f0f13be979d19b86f8439b934cc27a8">gr_gcd</a> (<span class="keywordtype">long</span> m, <span class="keywordtype">long</span> n);
<a name="l00039"></a>00039
<a name="l00040"></a>00040 <span class="comment">// returns a non-zero value if value is "not-a-number" (NaN), and 0 otherwise</span>
<a name="l00041"></a>00041 <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a81f89fcec612a38b4cf06a34b29c9bcb">gr_isnan</a> (<span class="keywordtype">double</span> value);
<a name="l00042"></a>00042
<a name="l00043"></a>00043 <span class="comment">// returns a non-zero value if the value of x has its sign bit set.</span>
<a name="l00044"></a>00044 <span class="comment">//</span>
<a name="l00045"></a>00045 <span class="comment">// This is not the same as `x < 0.0', because IEEE 754 floating point</span>
<a name="l00046"></a>00046 <span class="comment">// allows zero to be signed. The comparison `-0.0 < 0.0' is false, but</span>
<a name="l00047"></a>00047 <span class="comment">// `gr_signbit (-0.0)' will return a nonzero value.</span>
<a name="l00048"></a>00048
<a name="l00049"></a>00049 <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a77a6f0234e781a4ab2bf0a019a022726">gr_signbit</a> (<span class="keywordtype">double</span> x);
<a name="l00050"></a>00050 <span class="comment"></span>
<a name="l00051"></a>00051 <span class="comment">/*!</span>
<a name="l00052"></a>00052 <span class="comment"> * \brief Fast arc tangent using table lookup and linear interpolation</span>
<a name="l00053"></a>00053 <span class="comment"> * \ingroup misc</span>
<a name="l00054"></a>00054 <span class="comment"> *</span>
<a name="l00055"></a>00055 <span class="comment"> * \param y component of input vector</span>
<a name="l00056"></a>00056 <span class="comment"> * \param x component of input vector</span>
<a name="l00057"></a>00057 <span class="comment"> * \returns float angle angle of vector (x, y) in radians</span>
<a name="l00058"></a>00058 <span class="comment"> *</span>
<a name="l00059"></a>00059 <span class="comment"> * This function calculates the angle of the vector (x,y) based on a</span>
<a name="l00060"></a>00060 <span class="comment"> * table lookup and linear interpolation. The table uses a 256 point</span>
<a name="l00061"></a>00061 <span class="comment"> * table covering -45 to +45 degrees and uses symetry to determine the</span>
<a name="l00062"></a>00062 <span class="comment"> * final angle value in the range of -180 to 180 degrees. Note that</span>
<a name="l00063"></a>00063 <span class="comment"> * this function uses the small angle approximation for values close</span>
<a name="l00064"></a>00064 <span class="comment"> * to zero. This routine calculates the arc tangent with an average</span>
<a name="l00065"></a>00065 <span class="comment"> * error of +/- 0.045 degrees.</span>
<a name="l00066"></a>00066 <span class="comment"> */</span>
<a name="l00067"></a>00067 <span class="keywordtype">float</span> <a class="code" href="group__misc.html#ga7934920e9dbe8204309c2fd68dce8e1c" title="Fast arc tangent using table lookup and linear interpolation.">gr_fast_atan2f</a>(<span class="keywordtype">float</span> y, <span class="keywordtype">float</span> x);
<a name="l00068"></a>00068
<a name="l00069"></a><a class="code" href="gr__math_8h.html#ae51b150b5480dc16864d7a9c128d4e2b">00069</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">float</span> <a class="code" href="group__misc.html#ga7934920e9dbe8204309c2fd68dce8e1c" title="Fast arc tangent using table lookup and linear interpolation.">gr_fast_atan2f</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> z)
<a name="l00070"></a>00070 {
<a name="l00071"></a>00071 <span class="keywordflow">return</span> <a class="code" href="group__misc.html#ga7934920e9dbe8204309c2fd68dce8e1c" title="Fast arc tangent using table lookup and linear interpolation.">gr_fast_atan2f</a>(z.imag(), z.real());
<a name="l00072"></a>00072 }
<a name="l00073"></a>00073
<a name="l00074"></a>00074 <span class="comment">/* This bounds x by +/- clip without a branch */</span>
<a name="l00075"></a><a class="code" href="gr__math_8h.html#ae41ea9e5b184df9e439a21d31350ab14">00075</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">float</span> <a class="code" href="gr__math_8h.html#ae41ea9e5b184df9e439a21d31350ab14">gr_branchless_clip</a>(<span class="keywordtype">float</span> x, <span class="keywordtype">float</span> clip)
<a name="l00076"></a>00076 {
<a name="l00077"></a>00077 <span class="keywordtype">float</span> x1 = fabsf(x+clip);
<a name="l00078"></a>00078 <span class="keywordtype">float</span> x2 = fabsf(x-clip);
<a name="l00079"></a>00079 x1 -= x2;
<a name="l00080"></a>00080 <span class="keywordflow">return</span> 0.5*x1;
<a name="l00081"></a>00081 }
<a name="l00082"></a>00082
<a name="l00083"></a><a class="code" href="gr__math_8h.html#a752a37cb09d7d71aebb5b05e4de828fd">00083</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">float</span> <a class="code" href="gr__math_8h.html#a752a37cb09d7d71aebb5b05e4de828fd">gr_clip</a>(<span class="keywordtype">float</span> x, <span class="keywordtype">float</span> clip)
<a name="l00084"></a>00084 {
<a name="l00085"></a>00085 <span class="keywordtype">float</span> y = x;
<a name="l00086"></a>00086 <span class="keywordflow">if</span>(x > clip)
<a name="l00087"></a>00087 y = clip;
<a name="l00088"></a>00088 <span class="keywordflow">else</span> <span class="keywordflow">if</span>(x < -clip)
<a name="l00089"></a>00089 y = -clip;
<a name="l00090"></a>00090 <span class="keywordflow">return</span> y;
<a name="l00091"></a>00091 }
<a name="l00092"></a>00092
<a name="l00093"></a>00093 <span class="comment">// Slicer Functions</span>
<a name="l00094"></a><a class="code" href="gr__math_8h.html#a146f18980bcd8bcca5ec31a53fa7b18b">00094</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a146f18980bcd8bcca5ec31a53fa7b18b">gr_binary_slicer</a>(<span class="keywordtype">float</span> x)
<a name="l00095"></a>00095 {
<a name="l00096"></a>00096 <span class="keywordflow">if</span>(x >= 0)
<a name="l00097"></a>00097 <span class="keywordflow">return</span> 1;
<a name="l00098"></a>00098 <span class="keywordflow">else</span>
<a name="l00099"></a>00099 <span class="keywordflow">return</span> 0;
<a name="l00100"></a>00100 }
<a name="l00101"></a>00101
<a name="l00102"></a><a class="code" href="gr__math_8h.html#a628599d27233b3c1327eafb7cfab9f3f">00102</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a628599d27233b3c1327eafb7cfab9f3f">gr_quad_45deg_slicer</a>(<span class="keywordtype">float</span> r, <span class="keywordtype">float</span> i)
<a name="l00103"></a>00103 {
<a name="l00104"></a>00104 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> ret = 0;
<a name="l00105"></a>00105 <span class="keywordflow">if</span>((r >= 0) && (i >= 0))
<a name="l00106"></a>00106 ret = 0;
<a name="l00107"></a>00107 <span class="keywordflow">else</span> <span class="keywordflow">if</span>((r < 0) && (i >= 0))
<a name="l00108"></a>00108 ret = 1;
<a name="l00109"></a>00109 <span class="keywordflow">else</span> <span class="keywordflow">if</span>((r < 0) && (i < 0))
<a name="l00110"></a>00110 ret = 2;
<a name="l00111"></a>00111 <span class="keywordflow">else</span>
<a name="l00112"></a>00112 ret = 3;
<a name="l00113"></a>00113 <span class="keywordflow">return</span> ret;
<a name="l00114"></a>00114 }
<a name="l00115"></a>00115
<a name="l00116"></a><a class="code" href="gr__math_8h.html#a20720d374a5d5f77ba63e0e78b84ca5c">00116</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a20720d374a5d5f77ba63e0e78b84ca5c">gr_quad_0deg_slicer</a>(<span class="keywordtype">float</span> r, <span class="keywordtype">float</span> i)
<a name="l00117"></a>00117 {
<a name="l00118"></a>00118 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> ret = 0;
<a name="l00119"></a>00119 <span class="keywordflow">if</span>(fabsf(r) > fabsf(i)) {
<a name="l00120"></a>00120 <span class="keywordflow">if</span>(r > 0)
<a name="l00121"></a>00121 ret = 0;
<a name="l00122"></a>00122 <span class="keywordflow">else</span>
<a name="l00123"></a>00123 ret = 2;
<a name="l00124"></a>00124 }
<a name="l00125"></a>00125 <span class="keywordflow">else</span> {
<a name="l00126"></a>00126 <span class="keywordflow">if</span>(i > 0)
<a name="l00127"></a>00127 ret = 1;
<a name="l00128"></a>00128 <span class="keywordflow">else</span>
<a name="l00129"></a>00129 ret = 3;
<a name="l00130"></a>00130 }
<a name="l00131"></a>00131
<a name="l00132"></a>00132 <span class="keywordflow">return</span> ret;
<a name="l00133"></a>00133 }
<a name="l00134"></a>00134
<a name="l00135"></a><a class="code" href="gr__math_8h.html#a270ae32e0f8c3408f12fa552f144e6fa">00135</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a628599d27233b3c1327eafb7cfab9f3f">gr_quad_45deg_slicer</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> x)
<a name="l00136"></a>00136 {
<a name="l00137"></a>00137 <span class="keywordflow">return</span> <a class="code" href="gr__math_8h.html#a628599d27233b3c1327eafb7cfab9f3f">gr_quad_45deg_slicer</a>(x.real(), x.imag());
<a name="l00138"></a>00138 }
<a name="l00139"></a>00139
<a name="l00140"></a><a class="code" href="gr__math_8h.html#aac806dad801ca55a9203720754cf86e9">00140</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a20720d374a5d5f77ba63e0e78b84ca5c">gr_quad_0deg_slicer</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> x)
<a name="l00141"></a>00141 {
<a name="l00142"></a>00142 <span class="keywordflow">return</span> <a class="code" href="gr__math_8h.html#a20720d374a5d5f77ba63e0e78b84ca5c">gr_quad_0deg_slicer</a>(x.real(), x.imag());
<a name="l00143"></a>00143 }
<a name="l00144"></a>00144
<a name="l00145"></a>00145 <span class="comment">// Branchless Slicer Functions</span>
<a name="l00146"></a><a class="code" href="gr__math_8h.html#a30b60181accc9a0f40aee29ec2c95d50">00146</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a30b60181accc9a0f40aee29ec2c95d50">gr_branchless_binary_slicer</a>(<span class="keywordtype">float</span> x)
<a name="l00147"></a>00147 {
<a name="l00148"></a>00148 <span class="keywordflow">return</span> (x >= 0);
<a name="l00149"></a>00149 }
<a name="l00150"></a>00150
<a name="l00151"></a><a class="code" href="gr__math_8h.html#a9164ae9b083d3690dbcf0f0074b0d8c2">00151</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a9164ae9b083d3690dbcf0f0074b0d8c2">gr_branchless_quad_0deg_slicer</a>(<span class="keywordtype">float</span> r, <span class="keywordtype">float</span> i)
<a name="l00152"></a>00152 {
<a name="l00153"></a>00153 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> ret = 0;
<a name="l00154"></a>00154 ret = (fabsf(r) > fabsf(i)) * (((r < 0) << 0x1)); <span class="comment">// either 0 (00) or 2 (10)</span>
<a name="l00155"></a>00155 ret |= (fabsf(i) > fabsf(r)) * (((i < 0) << 0x1) | 0x1); <span class="comment">// either 1 (01) or 3 (11)</span>
<a name="l00156"></a>00156
<a name="l00157"></a>00157 <span class="keywordflow">return</span> ret;
<a name="l00158"></a>00158 }
<a name="l00159"></a>00159
<a name="l00160"></a><a class="code" href="gr__math_8h.html#a2c99fd1f6662416c025bb4d3d95adf48">00160</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#a9164ae9b083d3690dbcf0f0074b0d8c2">gr_branchless_quad_0deg_slicer</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> x)
<a name="l00161"></a>00161 {
<a name="l00162"></a>00162 <span class="keywordflow">return</span> <a class="code" href="gr__math_8h.html#a9164ae9b083d3690dbcf0f0074b0d8c2">gr_branchless_quad_0deg_slicer</a>(x.real(), x.imag());
<a name="l00163"></a>00163 }
<a name="l00164"></a>00164
<a name="l00165"></a><a class="code" href="gr__math_8h.html#aa535abb2054c204787c36dcfc090abc6">00165</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#aa535abb2054c204787c36dcfc090abc6">gr_branchless_quad_45deg_slicer</a>(<span class="keywordtype">float</span> r, <span class="keywordtype">float</span> i)
<a name="l00166"></a>00166 {
<a name="l00167"></a>00167 <span class="keywordtype">char</span> ret = (r <= 0);
<a name="l00168"></a>00168 ret |= ((i <= 0) << 1);
<a name="l00169"></a>00169 <span class="keywordflow">return</span> (ret ^ ((ret & 0x2) >> 0x1));
<a name="l00170"></a>00170 }
<a name="l00171"></a>00171
<a name="l00172"></a><a class="code" href="gr__math_8h.html#a568ec0c5ac906bc3310b74fc62a6dd7e">00172</a> <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="gr__math_8h.html#aa535abb2054c204787c36dcfc090abc6">gr_branchless_quad_45deg_slicer</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> x)
<a name="l00173"></a>00173 {
<a name="l00174"></a>00174 <span class="keywordflow">return</span> <a class="code" href="gr__math_8h.html#aa535abb2054c204787c36dcfc090abc6">gr_branchless_quad_45deg_slicer</a>(x.real(), x.imag());
<a name="l00175"></a>00175 }
<a name="l00176"></a>00176 <span class="comment"></span>
<a name="l00177"></a>00177 <span class="comment">/*!</span>
<a name="l00178"></a>00178 <span class="comment"> * \param x any value</span>
<a name="l00179"></a>00179 <span class="comment"> * \param pow2 must be a power of 2</span>
<a name="l00180"></a>00180 <span class="comment"> * \returns \p x rounded down to a multiple of \p pow2.</span>
<a name="l00181"></a>00181 <span class="comment"> */</span>
<a name="l00182"></a>00182 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">size_t</span>
<a name="l00183"></a><a class="code" href="gr__math_8h.html#a65081204f407632482da47b165b942e6">00183</a> <a class="code" href="gr__math_8h.html#a65081204f407632482da47b165b942e6">gr_p2_round_down</a>(<span class="keywordtype">size_t</span> x, <span class="keywordtype">size_t</span> pow2)
<a name="l00184"></a>00184 {
<a name="l00185"></a>00185 <span class="keywordflow">return</span> x & -pow2;
<a name="l00186"></a>00186 }
<a name="l00187"></a>00187 <span class="comment"></span>
<a name="l00188"></a>00188 <span class="comment">/*!</span>
<a name="l00189"></a>00189 <span class="comment"> * \param x any value</span>
<a name="l00190"></a>00190 <span class="comment"> * \param pow2 must be a power of 2</span>
<a name="l00191"></a>00191 <span class="comment"> * \returns \p x rounded up to a multiple of \p pow2.</span>
<a name="l00192"></a>00192 <span class="comment"> */</span>
<a name="l00193"></a>00193 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">size_t</span>
<a name="l00194"></a><a class="code" href="gr__math_8h.html#a8acadaea988a25fc1601d9b8b5e8a951">00194</a> <a class="code" href="gr__math_8h.html#a8acadaea988a25fc1601d9b8b5e8a951">gr_p2_round_up</a>(<span class="keywordtype">size_t</span> x, <span class="keywordtype">size_t</span> pow2)
<a name="l00195"></a>00195 {
<a name="l00196"></a>00196 <span class="keywordflow">return</span> <a class="code" href="gr__math_8h.html#a65081204f407632482da47b165b942e6">gr_p2_round_down</a>(x + pow2 - 1, pow2);
<a name="l00197"></a>00197 }
<a name="l00198"></a>00198 <span class="comment"></span>
<a name="l00199"></a>00199 <span class="comment">/*!</span>
<a name="l00200"></a>00200 <span class="comment"> * \param x any value</span>
<a name="l00201"></a>00201 <span class="comment"> * \param pow2 must be a power of 2</span>
<a name="l00202"></a>00202 <span class="comment"> * \returns \p x modulo \p pow2.</span>
<a name="l00203"></a>00203 <span class="comment"> */</span>
<a name="l00204"></a>00204 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">size_t</span>
<a name="l00205"></a><a class="code" href="gr__math_8h.html#aba9d6b1ba2198fde6ffe2a14620df26e">00205</a> <a class="code" href="gr__math_8h.html#aba9d6b1ba2198fde6ffe2a14620df26e">gr_p2_modulo</a>(<span class="keywordtype">size_t</span> x, <span class="keywordtype">size_t</span> pow2)
<a name="l00206"></a>00206 {
<a name="l00207"></a>00207 <span class="keywordflow">return</span> x & (pow2 - 1);
<a name="l00208"></a>00208 }
<a name="l00209"></a>00209 <span class="comment"></span>
<a name="l00210"></a>00210 <span class="comment">/*!</span>
<a name="l00211"></a>00211 <span class="comment"> * \param x any value</span>
<a name="l00212"></a>00212 <span class="comment"> * \param pow2 must be a power of 2</span>
<a name="l00213"></a>00213 <span class="comment"> * \returns \p pow2 - (\p x modulo \p pow2).</span>
<a name="l00214"></a>00214 <span class="comment"> */</span>
<a name="l00215"></a>00215 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">size_t</span>
<a name="l00216"></a><a class="code" href="gr__math_8h.html#a0a25383360574c5f3e287063dacc8023">00216</a> <a class="code" href="gr__math_8h.html#a0a25383360574c5f3e287063dacc8023">gr_p2_modulo_neg</a>(<span class="keywordtype">size_t</span> x, <span class="keywordtype">size_t</span> pow2)
<a name="l00217"></a>00217 {
<a name="l00218"></a>00218 <span class="keywordflow">return</span> pow2 - <a class="code" href="gr__math_8h.html#aba9d6b1ba2198fde6ffe2a14620df26e">gr_p2_modulo</a>(x, pow2);
<a name="l00219"></a>00219 }
<a name="l00220"></a>00220
<a name="l00221"></a>00221 <span class="preprocessor">#endif </span><span class="comment">/* _GR_MATH_H_ */</span>
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