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<h1>gr_fxpt.h</h1> </div>
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<a href="gr__fxpt_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 2004 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 <span class="preprocessor">#ifndef INCLUDED_GR_FXPT_H</span>
<a name="l00023"></a>00023 <span class="preprocessor"></span><span class="preprocessor">#define INCLUDED_GR_FXPT_H</span>
<a name="l00024"></a>00024 <span class="preprocessor"></span>
<a name="l00025"></a>00025 <span class="preprocessor">#include <gr_types.h></span>
<a name="l00026"></a>00026 <span class="comment"></span>
<a name="l00027"></a>00027 <span class="comment">/*!</span>
<a name="l00028"></a>00028 <span class="comment"> * \brief fixed point sine and cosine and friends.</span>
<a name="l00029"></a>00029 <span class="comment"> * \ingroup misc</span>
<a name="l00030"></a>00030 <span class="comment"> *</span>
<a name="l00031"></a>00031 <span class="comment"> * fixed pt radians</span>
<a name="l00032"></a>00032 <span class="comment"> * --------- --------</span>
<a name="l00033"></a>00033 <span class="comment"> * -2**31 -pi</span>
<a name="l00034"></a>00034 <span class="comment"> * 0 0</span>
<a name="l00035"></a>00035 <span class="comment"> * 2**31-1 pi - epsilon</span>
<a name="l00036"></a>00036 <span class="comment"> *</span>
<a name="l00037"></a>00037 <span class="comment"> */</span>
<a name="l00038"></a><a class="code" href="classgr__fxpt.html">00038</a> <span class="keyword">class </span><a class="code" href="classgr__fxpt.html" title="fixed point sine and cosine and friends.fixed pt radians --------- -------- -2**31 -pi 0 0 2**31-1 pi...">gr_fxpt</a>
<a name="l00039"></a>00039 {
<a name="l00040"></a>00040 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">int</span> WORDBITS = 32;
<a name="l00041"></a>00041 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">int</span> NBITS = 10;
<a name="l00042"></a>00042 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">float</span> s_sine_table[1 << NBITS][2];
<a name="l00043"></a>00043 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">float</span> PI = 3.14159265358979323846;
<a name="l00044"></a>00044 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">float</span> TWO_TO_THE_31 = 2147483648.0;
<a name="l00045"></a>00045 <span class="keyword">public</span>:
<a name="l00046"></a>00046
<a name="l00047"></a>00047 <span class="keyword">static</span> <a class="code" href="gr__types_8h.html#ac07cda22882f844c0aa1633d49f1c144">gr_int32</a>
<a name="l00048"></a><a class="code" href="classgr__fxpt.html#a8cf5f6942dd8db09072fb711d09b4820">00048</a> <a class="code" href="classgr__fxpt.html#a8cf5f6942dd8db09072fb711d09b4820">float_to_fixed</a> (<span class="keywordtype">float</span> x)
<a name="l00049"></a>00049 {
<a name="l00050"></a>00050 <span class="keywordflow">return</span> (<a class="code" href="gr__types_8h.html#ac07cda22882f844c0aa1633d49f1c144">gr_int32</a>) ((float) x * TWO_TO_THE_31 / PI);
<a name="l00051"></a>00051 }
<a name="l00052"></a>00052
<a name="l00053"></a>00053 <span class="keyword">static</span> <span class="keywordtype">float</span>
<a name="l00054"></a><a class="code" href="classgr__fxpt.html#a4b89af0770b5c4751f52224976514c20">00054</a> <a class="code" href="classgr__fxpt.html#a4b89af0770b5c4751f52224976514c20">fixed_to_float</a> (<a class="code" href="gr__types_8h.html#ac07cda22882f844c0aa1633d49f1c144">gr_int32</a> x)
<a name="l00055"></a>00055 {
<a name="l00056"></a>00056 <span class="keywordflow">return</span> x * (PI / TWO_TO_THE_31);
<a name="l00057"></a>00057 }
<a name="l00058"></a>00058 <span class="comment"></span>
<a name="l00059"></a>00059 <span class="comment"> /*!</span>
<a name="l00060"></a>00060 <span class="comment"> * \brief Given a fixed point angle x, return float sine (x)</span>
<a name="l00061"></a>00061 <span class="comment"> */</span>
<a name="l00062"></a>00062 <span class="keyword">static</span> <span class="keywordtype">float</span>
<a name="l00063"></a><a class="code" href="classgr__fxpt.html#a26312e3f31f6d7a6ae4810c05f30979a">00063</a> <a class="code" href="classgr__fxpt.html#a26312e3f31f6d7a6ae4810c05f30979a" title="Given a fixed point angle x, return float sine (x)">sin</a> (<a class="code" href="gr__types_8h.html#ac07cda22882f844c0aa1633d49f1c144">gr_int32</a> x)
<a name="l00064"></a>00064 {
<a name="l00065"></a>00065 <a class="code" href="gr__types_8h.html#a89e5afa41619bc5b0694d38709297d47">gr_uint32</a> ux = x;
<a name="l00066"></a>00066 <span class="keywordtype">int</span> index = ux >> (WORDBITS - NBITS);
<a name="l00067"></a>00067 <span class="keywordflow">return</span> s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
<a name="l00068"></a>00068 }
<a name="l00069"></a>00069
<a name="l00070"></a>00070 <span class="comment">/*</span>
<a name="l00071"></a>00071 <span class="comment"> * \brief Given a fixed point angle x, return float cosine (x)</span>
<a name="l00072"></a>00072 <span class="comment"> */</span>
<a name="l00073"></a>00073 <span class="keyword">static</span> <span class="keywordtype">float</span>
<a name="l00074"></a><a class="code" href="classgr__fxpt.html#a61861c9e4535e05a567a96a2551430a9">00074</a> <a class="code" href="classgr__fxpt.html#a61861c9e4535e05a567a96a2551430a9">cos</a> (<a class="code" href="gr__types_8h.html#ac07cda22882f844c0aa1633d49f1c144">gr_int32</a> x)
<a name="l00075"></a>00075 {
<a name="l00076"></a>00076 <a class="code" href="gr__types_8h.html#a89e5afa41619bc5b0694d38709297d47">gr_uint32</a> ux = x + 0x40000000;
<a name="l00077"></a>00077 <span class="keywordtype">int</span> index = ux >> (WORDBITS - NBITS);
<a name="l00078"></a>00078 <span class="keywordflow">return</span> s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
<a name="l00079"></a>00079 }
<a name="l00080"></a>00080
<a name="l00081"></a>00081 };
<a name="l00082"></a>00082
<a name="l00083"></a>00083 <span class="preprocessor">#endif </span><span class="comment">/* INCLUDED_GR_FXPT_H */</span>
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