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<h1>src/algorithm.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// ---------------------------------------------------------------------</span>
<a name="l00002"></a>00002 <span class="comment">// pion: a Boost C++ framework for building lightweight HTTP interfaces</span>
<a name="l00003"></a>00003 <span class="comment">// ---------------------------------------------------------------------</span>
<a name="l00004"></a>00004 <span class="comment">// Copyright (C) 2007-2012 Cloudmeter, Inc. (http://www.cloudmeter.com)</span>
<a name="l00005"></a>00005 <span class="comment">//</span>
<a name="l00006"></a>00006 <span class="comment">// Distributed under the Boost Software License, Version 1.0.</span>
<a name="l00007"></a>00007 <span class="comment">// See http://www.boost.org/LICENSE_1_0.txt</span>
<a name="l00008"></a>00008 <span class="comment">//</span>
<a name="l00009"></a>00009
<a name="l00010"></a>00010 <span class="preprocessor">#include <cmath></span>
<a name="l00011"></a>00011 <span class="preprocessor">#include <cstdlib></span>
<a name="l00012"></a>00012 <span class="preprocessor">#include <cstdio></span>
<a name="l00013"></a>00013 <span class="preprocessor">#include <cstring></span>
<a name="l00014"></a>00014 <span class="preprocessor">#include <pion/algorithm.hpp></span>
<a name="l00015"></a>00015 <span class="preprocessor">#include <boost/assert.hpp></span>
<a name="l00016"></a>00016
<a name="l00017"></a>00017 <span class="comment">// macro to shift bitmask by a single bit</span>
<a name="l00018"></a>00018 <span class="preprocessor">#define SHIFT_BITMASK(ptr, mask) if (mask & 0x01) { mask = 0x80; ++ptr; } else mask >>= 1;</span>
<a name="l00019"></a>00019 <span class="preprocessor"></span>
<a name="l00020"></a>00020
<a name="l00021"></a>00021 <span class="keyword">namespace </span>pion { <span class="comment">// begin namespace pion</span>
<a name="l00022"></a>00022
<a name="l00023"></a>00023
<a name="l00024"></a><a class="code" href="structpion_1_1algorithm.html#ad1700ce7cf8e29bb7600d5729fd4cdad">00024</a> <span class="keywordtype">bool</span> <a class="code" href="structpion_1_1algorithm.html#ad1700ce7cf8e29bb7600d5729fd4cdad">algorithm::base64_decode</a>(<span class="keyword">const</span> std::string &input, std::string &output)
<a name="l00025"></a>00025 {
<a name="l00026"></a>00026 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">char</span> nop = -1;
<a name="l00027"></a>00027 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">char</span> decoding_data[] = {
<a name="l00028"></a>00028 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00029"></a>00029 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00030"></a>00030 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop, 62, nop,nop,nop, 63,
<a name="l00031"></a>00031 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,nop,nop, nop,nop,nop,nop,
<a name="l00032"></a>00032 nop, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
<a name="l00033"></a>00033 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,nop, nop,nop,nop,nop,
<a name="l00034"></a>00034 nop,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
<a name="l00035"></a>00035 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,nop, nop,nop,nop,nop,
<a name="l00036"></a>00036 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00037"></a>00037 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00038"></a>00038 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00039"></a>00039 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00040"></a>00040 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00041"></a>00041 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00042"></a>00042 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop,
<a name="l00043"></a>00043 nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop, nop,nop,nop,nop
<a name="l00044"></a>00044 };
<a name="l00045"></a>00045
<a name="l00046"></a>00046 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> input_length=input.size();
<a name="l00047"></a>00047 <span class="keyword">const</span> <span class="keywordtype">char</span> * input_ptr = input.data();
<a name="l00048"></a>00048
<a name="l00049"></a>00049 <span class="comment">// allocate space for output string</span>
<a name="l00050"></a>00050 output.clear();
<a name="l00051"></a>00051 output.reserve(((input_length+2)/3)*4);
<a name="l00052"></a>00052
<a name="l00053"></a>00053 <span class="comment">// for each 4-bytes sequence from the input, extract 4 6-bits sequences by droping first two bits</span>
<a name="l00054"></a>00054 <span class="comment">// and regenerate into 3 8-bits sequence</span>
<a name="l00055"></a>00055
<a name="l00056"></a>00056 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<input_length;i++) {
<a name="l00057"></a>00057 <span class="keywordtype">char</span> base64code0;
<a name="l00058"></a>00058 <span class="keywordtype">char</span> base64code1;
<a name="l00059"></a>00059 <span class="keywordtype">char</span> base64code2 = 0; <span class="comment">// initialized to 0 to suppress warnings</span>
<a name="l00060"></a>00060 <span class="keywordtype">char</span> base64code3;
<a name="l00061"></a>00061
<a name="l00062"></a>00062 base64code0 = decoding_data[<span class="keyword">static_cast<</span><span class="keywordtype">int</span><span class="keyword">></span>(input_ptr[i])];
<a name="l00063"></a>00063 <span class="keywordflow">if</span>(base64code0==nop) <span class="comment">// non base64 character</span>
<a name="l00064"></a>00064 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00065"></a>00065 <span class="keywordflow">if</span>(!(++i<input_length)) <span class="comment">// we need at least two input bytes for first byte output</span>
<a name="l00066"></a>00066 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00067"></a>00067 base64code1 = decoding_data[<span class="keyword">static_cast<</span><span class="keywordtype">int</span><span class="keyword">></span>(input_ptr[i])];
<a name="l00068"></a>00068 <span class="keywordflow">if</span>(base64code1==nop) <span class="comment">// non base64 character</span>
<a name="l00069"></a>00069 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00070"></a>00070
<a name="l00071"></a>00071 output += ((base64code0 << 2) | ((base64code1 >> 4) & 0x3));
<a name="l00072"></a>00072
<a name="l00073"></a>00073 <span class="keywordflow">if</span>(++i<input_length) {
<a name="l00074"></a>00074 <span class="keywordtype">char</span> c = input_ptr[i];
<a name="l00075"></a>00075 <span class="keywordflow">if</span>(c ==<span class="charliteral">'='</span>) { <span class="comment">// padding , end of input</span>
<a name="l00076"></a>00076 BOOST_ASSERT( (base64code1 & 0x0f)==0);
<a name="l00077"></a>00077 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00078"></a>00078 }
<a name="l00079"></a>00079 base64code2 = decoding_data[<span class="keyword">static_cast<</span><span class="keywordtype">int</span><span class="keyword">></span>(input_ptr[i])];
<a name="l00080"></a>00080 <span class="keywordflow">if</span>(base64code2==nop) <span class="comment">// non base64 character</span>
<a name="l00081"></a>00081 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00082"></a>00082
<a name="l00083"></a>00083 output += ((base64code1 << 4) & 0xf0) | ((base64code2 >> 2) & 0x0f);
<a name="l00084"></a>00084 }
<a name="l00085"></a>00085
<a name="l00086"></a>00086 <span class="keywordflow">if</span>(++i<input_length) {
<a name="l00087"></a>00087 <span class="keywordtype">char</span> c = input_ptr[i];
<a name="l00088"></a>00088 <span class="keywordflow">if</span>(c ==<span class="charliteral">'='</span>) { <span class="comment">// padding , end of input</span>
<a name="l00089"></a>00089 BOOST_ASSERT( (base64code2 & 0x03)==0);
<a name="l00090"></a>00090 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00091"></a>00091 }
<a name="l00092"></a>00092 base64code3 = decoding_data[<span class="keyword">static_cast<</span><span class="keywordtype">int</span><span class="keyword">></span>(input_ptr[i])];
<a name="l00093"></a>00093 <span class="keywordflow">if</span>(base64code3==nop) <span class="comment">// non base64 character</span>
<a name="l00094"></a>00094 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00095"></a>00095
<a name="l00096"></a>00096 output += (((base64code2 << 6) & 0xc0) | base64code3 );
<a name="l00097"></a>00097 }
<a name="l00098"></a>00098
<a name="l00099"></a>00099 }
<a name="l00100"></a>00100
<a name="l00101"></a>00101 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00102"></a>00102 }
<a name="l00103"></a>00103
<a name="l00104"></a><a class="code" href="structpion_1_1algorithm.html#ae5f52e52ac349ecf20410f2ad3e257dd">00104</a> <span class="keywordtype">bool</span> <a class="code" href="structpion_1_1algorithm.html#ae5f52e52ac349ecf20410f2ad3e257dd">algorithm::base64_encode</a>(<span class="keyword">const</span> std::string &input, std::string &output)
<a name="l00105"></a>00105 {
<a name="l00106"></a>00106 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">char</span> encoding_data[] =
<a name="l00107"></a>00107 <span class="stringliteral">"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"</span>;
<a name="l00108"></a>00108
<a name="l00109"></a>00109 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> input_length=input.size();
<a name="l00110"></a>00110 <span class="keyword">const</span> <span class="keywordtype">char</span> * input_ptr = input.data();
<a name="l00111"></a>00111
<a name="l00112"></a>00112 <span class="comment">// allocate space for output string</span>
<a name="l00113"></a>00113 output.clear();
<a name="l00114"></a>00114 output.reserve(((input_length+2)/3)*4);
<a name="l00115"></a>00115
<a name="l00116"></a>00116 <span class="comment">// for each 3-bytes sequence from the input, extract 4 6-bits sequences and encode using </span>
<a name="l00117"></a>00117 <span class="comment">// encoding_data lookup table.</span>
<a name="l00118"></a>00118 <span class="comment">// if input do not contains enough chars to complete 3-byte sequence,use pad char '=' </span>
<a name="l00119"></a>00119 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<input_length;i++) {
<a name="l00120"></a>00120 <span class="keywordtype">int</span> base64code0=0;
<a name="l00121"></a>00121 <span class="keywordtype">int</span> base64code1=0;
<a name="l00122"></a>00122 <span class="keywordtype">int</span> base64code2=0;
<a name="l00123"></a>00123 <span class="keywordtype">int</span> base64code3=0;
<a name="l00124"></a>00124
<a name="l00125"></a>00125 base64code0 = (input_ptr[i] >> 2) & 0x3f; <span class="comment">// 1-byte 6 bits</span>
<a name="l00126"></a>00126 output += encoding_data[base64code0];
<a name="l00127"></a>00127 base64code1 = (input_ptr[i] << 4 ) & 0x3f; <span class="comment">// 1-byte 2 bits +</span>
<a name="l00128"></a>00128
<a name="l00129"></a>00129 <span class="keywordflow">if</span> (++i < input_length) {
<a name="l00130"></a>00130 base64code1 |= (input_ptr[i] >> 4) & 0x0f; <span class="comment">// 2-byte 4 bits</span>
<a name="l00131"></a>00131 output += encoding_data[base64code1];
<a name="l00132"></a>00132 base64code2 = (input_ptr[i] << 2) & 0x3f; <span class="comment">// 2-byte 4 bits + </span>
<a name="l00133"></a>00133
<a name="l00134"></a>00134 <span class="keywordflow">if</span> (++i < input_length) {
<a name="l00135"></a>00135 base64code2 |= (input_ptr[i] >> 6) & 0x03; <span class="comment">// 3-byte 2 bits</span>
<a name="l00136"></a>00136 base64code3 = input_ptr[i] & 0x3f; <span class="comment">// 3-byte 6 bits</span>
<a name="l00137"></a>00137 output += encoding_data[base64code2];
<a name="l00138"></a>00138 output += encoding_data[base64code3];
<a name="l00139"></a>00139 } <span class="keywordflow">else</span> {
<a name="l00140"></a>00140 output += encoding_data[base64code2];
<a name="l00141"></a>00141 output += <span class="charliteral">'='</span>;
<a name="l00142"></a>00142 }
<a name="l00143"></a>00143 } <span class="keywordflow">else</span> {
<a name="l00144"></a>00144 output += encoding_data[base64code1];
<a name="l00145"></a>00145 output += <span class="charliteral">'='</span>;
<a name="l00146"></a>00146 output += <span class="charliteral">'='</span>;
<a name="l00147"></a>00147 }
<a name="l00148"></a>00148 }
<a name="l00149"></a>00149
<a name="l00150"></a>00150 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00151"></a>00151 }
<a name="l00152"></a>00152
<a name="l00153"></a><a class="code" href="structpion_1_1algorithm.html#a440bd54b07a24c80bc939fdb03583721">00153</a> std::string <a class="code" href="structpion_1_1algorithm.html#a440bd54b07a24c80bc939fdb03583721" title="escapes URL-encoded strings (a20value+with20spaces)">algorithm::url_decode</a>(<span class="keyword">const</span> std::string& str)
<a name="l00154"></a>00154 {
<a name="l00155"></a>00155 <span class="keywordtype">char</span> decode_buf[3];
<a name="l00156"></a>00156 std::string result;
<a name="l00157"></a>00157 result.reserve(str.size());
<a name="l00158"></a>00158
<a name="l00159"></a>00159 <span class="keywordflow">for</span> (std::string::size_type pos = 0; pos < str.size(); ++pos) {
<a name="l00160"></a>00160 <span class="keywordflow">switch</span>(str[pos]) {
<a name="l00161"></a>00161 <span class="keywordflow">case</span> <span class="charliteral">'+'</span>:
<a name="l00162"></a>00162 <span class="comment">// convert to space character</span>
<a name="l00163"></a>00163 result += <span class="charliteral">' '</span>;
<a name="l00164"></a>00164 <span class="keywordflow">break</span>;
<a name="l00165"></a>00165 <span class="keywordflow">case</span> <span class="charliteral">'%'</span>:
<a name="l00166"></a>00166 <span class="comment">// decode hexidecimal value</span>
<a name="l00167"></a>00167 <span class="keywordflow">if</span> (pos + 2 < str.size()) {
<a name="l00168"></a>00168 decode_buf[0] = str[++pos];
<a name="l00169"></a>00169 decode_buf[1] = str[++pos];
<a name="l00170"></a>00170 decode_buf[2] = <span class="charliteral">'\0'</span>;
<a name="l00171"></a>00171 result += <span class="keyword">static_cast<</span><span class="keywordtype">char</span><span class="keyword">></span>( strtol(decode_buf, 0, 16) );
<a name="l00172"></a>00172 } <span class="keywordflow">else</span> {
<a name="l00173"></a>00173 <span class="comment">// recover from error by not decoding character</span>
<a name="l00174"></a>00174 result += <span class="charliteral">'%'</span>;
<a name="l00175"></a>00175 }
<a name="l00176"></a>00176 <span class="keywordflow">break</span>;
<a name="l00177"></a>00177 <span class="keywordflow">default</span>:
<a name="l00178"></a>00178 <span class="comment">// character does not need to be escaped</span>
<a name="l00179"></a>00179 result += str[pos];
<a name="l00180"></a>00180 }
<a name="l00181"></a>00181 };
<a name="l00182"></a>00182
<a name="l00183"></a>00183 <span class="keywordflow">return</span> result;
<a name="l00184"></a>00184 }
<a name="l00185"></a>00185
<a name="l00186"></a><a class="code" href="structpion_1_1algorithm.html#aa4eaedaecac95a638cedf5c4884de1b8">00186</a> std::string <a class="code" href="structpion_1_1algorithm.html#aa4eaedaecac95a638cedf5c4884de1b8" title="encodes strings so that they are safe for URLs (with20spaces)">algorithm::url_encode</a>(<span class="keyword">const</span> std::string& str)
<a name="l00187"></a>00187 {
<a name="l00188"></a>00188 <span class="keywordtype">char</span> encode_buf[4];
<a name="l00189"></a>00189 std::string result;
<a name="l00190"></a>00190 encode_buf[0] = <span class="charliteral">'%'</span>;
<a name="l00191"></a>00191 result.reserve(str.size());
<a name="l00192"></a>00192
<a name="l00193"></a>00193 <span class="comment">// character selection for this algorithm is based on the following url:</span>
<a name="l00194"></a>00194 <span class="comment">// http://www.blooberry.com/indexdot/html/topics/urlencoding.htm</span>
<a name="l00195"></a>00195
<a name="l00196"></a>00196 <span class="keywordflow">for</span> (std::string::size_type pos = 0; pos < str.size(); ++pos) {
<a name="l00197"></a>00197 <span class="keywordflow">switch</span>(str[pos]) {
<a name="l00198"></a>00198 <span class="keywordflow">default</span>:
<a name="l00199"></a>00199 <span class="keywordflow">if</span> (str[pos] > 32 && str[pos] < 127) {
<a name="l00200"></a>00200 <span class="comment">// character does not need to be escaped</span>
<a name="l00201"></a>00201 result += str[pos];
<a name="l00202"></a>00202 <span class="keywordflow">break</span>;
<a name="l00203"></a>00203 }
<a name="l00204"></a>00204 <span class="comment">// else pass through to next case</span>
<a name="l00205"></a>00205 <span class="keywordflow">case</span> <span class="charliteral">' '</span>:
<a name="l00206"></a>00206 <span class="keywordflow">case</span> <span class="charliteral">'$'</span>: <span class="keywordflow">case</span> <span class="charliteral">'&'</span>: <span class="keywordflow">case</span> <span class="charliteral">'+'</span>: <span class="keywordflow">case</span> <span class="charliteral">','</span>: <span class="keywordflow">case</span> <span class="charliteral">'/'</span>: <span class="keywordflow">case</span> <span class="charliteral">':'</span>:
<a name="l00207"></a>00207 <span class="keywordflow">case</span> <span class="charliteral">';'</span>: <span class="keywordflow">case</span> <span class="charliteral">'='</span>: <span class="keywordflow">case</span> <span class="charliteral">'?'</span>: <span class="keywordflow">case</span> <span class="charliteral">'@'</span>: <span class="keywordflow">case</span> <span class="charliteral">'"'</span>: <span class="keywordflow">case</span> <span class="charliteral">'<'</span>:
<a name="l00208"></a>00208 <span class="keywordflow">case</span> <span class="charliteral">'>'</span>: <span class="keywordflow">case</span> <span class="charliteral">'#'</span>: <span class="keywordflow">case</span> <span class="charliteral">'%'</span>: <span class="keywordflow">case</span> <span class="charliteral">'{'</span>: <span class="keywordflow">case</span> <span class="charliteral">'}'</span>: <span class="keywordflow">case</span> <span class="charliteral">'|'</span>:
<a name="l00209"></a>00209 <span class="keywordflow">case</span> <span class="charliteral">'\\'</span>: <span class="keywordflow">case</span> <span class="charliteral">'^'</span>: <span class="keywordflow">case</span> <span class="charliteral">'~'</span>: <span class="keywordflow">case</span> <span class="charliteral">'['</span>: <span class="keywordflow">case</span> <span class="charliteral">']'</span>: <span class="keywordflow">case</span> <span class="charliteral">'`'</span>:
<a name="l00210"></a>00210 <span class="comment">// the character needs to be encoded</span>
<a name="l00211"></a>00211 sprintf(encode_buf+1, <span class="stringliteral">"%.2X"</span>, (<span class="keywordtype">unsigned</span> <span class="keywordtype">char</span>)(str[pos]));
<a name="l00212"></a>00212 result += encode_buf;
<a name="l00213"></a>00213 <span class="keywordflow">break</span>;
<a name="l00214"></a>00214 }
<a name="l00215"></a>00215 };
<a name="l00216"></a>00216
<a name="l00217"></a>00217 <span class="keywordflow">return</span> result;
<a name="l00218"></a>00218 }
<a name="l00219"></a>00219
<a name="l00220"></a>00220 <span class="comment">// TODO</span>
<a name="l00221"></a>00221 <span class="comment">//std::string algorithm::xml_decode(const std::string& str)</span>
<a name="l00222"></a>00222 <span class="comment">//{</span>
<a name="l00223"></a>00223 <span class="comment">//}</span>
<a name="l00224"></a>00224
<a name="l00225"></a><a class="code" href="structpion_1_1algorithm.html#a2177ca0d0f01e6ef6d4d3bceb73d82bb">00225</a> std::string <a class="code" href="structpion_1_1algorithm.html#a2177ca0d0f01e6ef6d4d3bceb73d82bb" title="TODO: escapes XML/HTML-encoded strings (1 &lt; 2).">algorithm::xml_encode</a>(<span class="keyword">const</span> std::string& str)
<a name="l00226"></a>00226 {
<a name="l00227"></a>00227 std::string result;
<a name="l00228"></a>00228 result.reserve(str.size() + 20); <span class="comment">// Assume ~5 characters converted (length increases)</span>
<a name="l00229"></a>00229 <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *ptr = <span class="keyword">reinterpret_cast<</span><span class="keyword">const </span><span class="keywordtype">unsigned</span> <span class="keywordtype">char</span>*<span class="keyword">></span>(str.c_str());
<a name="l00230"></a>00230 <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *end_ptr = ptr + str.size();
<a name="l00231"></a>00231 <span class="keywordflow">while</span> (ptr < end_ptr) {
<a name="l00232"></a>00232 <span class="comment">// check byte ranges for valid UTF-8</span>
<a name="l00233"></a>00233 <span class="comment">// see http://en.wikipedia.org/wiki/UTF-8</span>
<a name="l00234"></a>00234 <span class="comment">// also, see http://www.w3.org/TR/REC-xml/#charsets</span>
<a name="l00235"></a>00235 <span class="comment">// this implementation is the strictest subset of both</span>
<a name="l00236"></a>00236 <span class="keywordflow">if</span> ((*ptr >= 0x20 && *ptr <= 0x7F) || *ptr == 0x9 || *ptr == 0xa || *ptr == 0xd) {
<a name="l00237"></a>00237 <span class="comment">// regular ASCII character</span>
<a name="l00238"></a>00238 <span class="keywordflow">switch</span>(*ptr) {
<a name="l00239"></a>00239 <span class="comment">// Escape special XML characters.</span>
<a name="l00240"></a>00240 <span class="keywordflow">case</span> <span class="charliteral">'&'</span>:
<a name="l00241"></a>00241 result += <span class="stringliteral">"&amp;"</span>;
<a name="l00242"></a>00242 <span class="keywordflow">break</span>;
<a name="l00243"></a>00243 <span class="keywordflow">case</span> <span class="charliteral">'<'</span>:
<a name="l00244"></a>00244 result += <span class="stringliteral">"&lt;"</span>;
<a name="l00245"></a>00245 <span class="keywordflow">break</span>;
<a name="l00246"></a>00246 <span class="keywordflow">case</span> <span class="charliteral">'>'</span>:
<a name="l00247"></a>00247 result += <span class="stringliteral">"&gt;"</span>;
<a name="l00248"></a>00248 <span class="keywordflow">break</span>;
<a name="l00249"></a>00249 <span class="keywordflow">case</span> <span class="charliteral">'\"'</span>:
<a name="l00250"></a>00250 result += <span class="stringliteral">"&quot;"</span>;
<a name="l00251"></a>00251 <span class="keywordflow">break</span>;
<a name="l00252"></a>00252 <span class="keywordflow">case</span> <span class="charliteral">'\''</span>:
<a name="l00253"></a>00253 result += <span class="stringliteral">"&apos;"</span>;
<a name="l00254"></a>00254 <span class="keywordflow">break</span>;
<a name="l00255"></a>00255 <span class="keywordflow">default</span>:
<a name="l00256"></a>00256 result += *ptr;
<a name="l00257"></a>00257 }
<a name="l00258"></a>00258 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (*ptr >= 0xC2 && *ptr <= 0xDF) {
<a name="l00259"></a>00259 <span class="comment">// two-byte sequence</span>
<a name="l00260"></a>00260 <span class="keywordflow">if</span> (*(ptr+1) >= 0x80 && *(ptr+1) <= 0xBF) {
<a name="l00261"></a>00261 result += *ptr;
<a name="l00262"></a>00262 result += *(++ptr);
<a name="l00263"></a>00263 } <span class="keywordflow">else</span> {
<a name="l00264"></a>00264 <span class="comment">// insert replacement char</span>
<a name="l00265"></a>00265 result += 0xef;
<a name="l00266"></a>00266 result += 0xbf;
<a name="l00267"></a>00267 result += 0xbd;
<a name="l00268"></a>00268 }
<a name="l00269"></a>00269 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (*ptr >= 0xE0 && *ptr <= 0xEF) {
<a name="l00270"></a>00270 <span class="comment">// three-byte sequence</span>
<a name="l00271"></a>00271 <span class="keywordflow">if</span> (*(ptr+1) >= 0x80 && *(ptr+1) <= 0xBF
<a name="l00272"></a>00272 && *(ptr+2) >= 0x80 && *(ptr+2) <= 0xBF) {
<a name="l00273"></a>00273 result += *ptr;
<a name="l00274"></a>00274 result += *(++ptr);
<a name="l00275"></a>00275 result += *(++ptr);
<a name="l00276"></a>00276 } <span class="keywordflow">else</span> {
<a name="l00277"></a>00277 <span class="comment">// insert replacement char</span>
<a name="l00278"></a>00278 result += 0xef;
<a name="l00279"></a>00279 result += 0xbf;
<a name="l00280"></a>00280 result += 0xbd;
<a name="l00281"></a>00281 }
<a name="l00282"></a>00282 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (*ptr >= 0xF0 && *ptr <= 0xF4) {
<a name="l00283"></a>00283 <span class="comment">// four-byte sequence</span>
<a name="l00284"></a>00284 <span class="keywordflow">if</span> (*(ptr+1) >= 0x80 && *(ptr+1) <= 0xBF
<a name="l00285"></a>00285 && *(ptr+2) >= 0x80 && *(ptr+2) <= 0xBF
<a name="l00286"></a>00286 && *(ptr+3) >= 0x80 && *(ptr+3) <= 0xBF) {
<a name="l00287"></a>00287 result += *ptr;
<a name="l00288"></a>00288 result += *(++ptr);
<a name="l00289"></a>00289 result += *(++ptr);
<a name="l00290"></a>00290 result += *(++ptr);
<a name="l00291"></a>00291 } <span class="keywordflow">else</span> {
<a name="l00292"></a>00292 <span class="comment">// insert replacement char</span>
<a name="l00293"></a>00293 result += 0xef;
<a name="l00294"></a>00294 result += 0xbf;
<a name="l00295"></a>00295 result += 0xbd;
<a name="l00296"></a>00296 }
<a name="l00297"></a>00297 } <span class="keywordflow">else</span> {
<a name="l00298"></a>00298 <span class="comment">// insert replacement char</span>
<a name="l00299"></a>00299 result += 0xef;
<a name="l00300"></a>00300 result += 0xbf;
<a name="l00301"></a>00301 result += 0xbd;
<a name="l00302"></a>00302 }
<a name="l00303"></a>00303 ++ptr;
<a name="l00304"></a>00304 }
<a name="l00305"></a>00305
<a name="l00306"></a>00306 <span class="keywordflow">return</span> result;
<a name="l00307"></a>00307 }
<a name="l00308"></a>00308
<a name="l00309"></a><a class="code" href="structpion_1_1algorithm.html#ab3cce74846661c3585ec5f540a99ff07">00309</a> <span class="keywordtype">void</span> <a class="code" href="structpion_1_1algorithm.html#ab3cce74846661c3585ec5f540a99ff07">algorithm::float_from_bytes</a>(<span class="keywordtype">long</span> <span class="keywordtype">double</span>& value, <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *ptr, <span class="keywordtype">size_t</span> num_exp_bits, <span class="keywordtype">size_t</span> num_fraction_bits)
<a name="l00310"></a>00310 {
<a name="l00311"></a>00311 <span class="comment">// get sign of the number from the first bit</span>
<a name="l00312"></a>00312 <span class="keyword">const</span> <span class="keywordtype">int</span> value_sign = (*ptr & 0x80) ? -1 : 1;
<a name="l00313"></a>00313
<a name="l00314"></a>00314 <span class="comment">// build exponent value from bitstream</span>
<a name="l00315"></a>00315 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> mask = 0x80;
<a name="l00316"></a>00316 boost::int16_t exponent = 0;
<a name="l00317"></a>00317 <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> n = 0; n < num_exp_bits; ++n) {
<a name="l00318"></a>00318 SHIFT_BITMASK(ptr, mask);
<a name="l00319"></a>00319 exponent *= 2;
<a name="l00320"></a>00320 <span class="keywordflow">if</span> (*ptr & mask)
<a name="l00321"></a>00321 exponent += 1;
<a name="l00322"></a>00322 }
<a name="l00323"></a>00323
<a name="l00324"></a>00324 <span class="comment">// build significand from bitstream</span>
<a name="l00325"></a>00325 <span class="keywordtype">long</span> <span class="keywordtype">double</span> significand = exponent ? 1.0 : 0.0;
<a name="l00326"></a>00326 <span class="keywordtype">long</span> <span class="keywordtype">double</span> significand_value = 1.0;
<a name="l00327"></a>00327 <span class="keywordflow">while</span> (num_fraction_bits) {
<a name="l00328"></a>00328 SHIFT_BITMASK(ptr, mask);
<a name="l00329"></a>00329 significand_value /= 2;
<a name="l00330"></a>00330 <span class="keywordflow">if</span> (*ptr & mask)
<a name="l00331"></a>00331 significand += significand_value;
<a name="l00332"></a>00332 --num_fraction_bits;
<a name="l00333"></a>00333 }
<a name="l00334"></a>00334
<a name="l00335"></a>00335 <span class="comment">// calculate final value</span>
<a name="l00336"></a>00336 exponent -= (::pow((<span class="keywordtype">long</span> double)2, (<span class="keywordtype">int</span>)(num_exp_bits - 1)) - 1);
<a name="l00337"></a>00337 value = value_sign * significand * ::pow((<span class="keywordtype">long</span> double)2, exponent);
<a name="l00338"></a>00338 }
<a name="l00339"></a>00339
<a name="l00340"></a><a class="code" href="structpion_1_1algorithm.html#a61872c7ccf75793a16d8ce7961f28842">00340</a> <span class="keywordtype">void</span> <a class="code" href="structpion_1_1algorithm.html#a61872c7ccf75793a16d8ce7961f28842">algorithm::float_to_bytes</a>(<span class="keywordtype">long</span> <span class="keywordtype">double</span> value, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *buf, <span class="keywordtype">size_t</span> num_exp_bits, <span class="keywordtype">size_t</span> num_fraction_bits)
<a name="l00341"></a>00341 {
<a name="l00342"></a>00342 <span class="comment">// first initialize output buffer to zeros</span>
<a name="l00343"></a>00343 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *ptr = buf;
<a name="l00344"></a>00344 memset(ptr, 0x00, ::ceil(static_cast<float>(num_exp_bits + num_fraction_bits + 1) / 8));
<a name="l00345"></a>00345
<a name="l00346"></a>00346 <span class="comment">// initialize first byte starting with sign of number</span>
<a name="l00347"></a>00347 <span class="keywordflow">if</span> (value < 0) {
<a name="l00348"></a>00348 *ptr = 0x80;
<a name="l00349"></a>00349 value *= -1;
<a name="l00350"></a>00350 }
<a name="l00351"></a>00351
<a name="l00352"></a>00352 <span class="comment">// break down numbers >= 1.0 by incrementing the exponent & dividing by 2</span>
<a name="l00353"></a>00353 boost::int16_t exponent = 0;
<a name="l00354"></a>00354 <span class="keywordflow">while</span> (value >= 1) {
<a name="l00355"></a>00355 value /= 2;
<a name="l00356"></a>00356 ++exponent;
<a name="l00357"></a>00357 }
<a name="l00358"></a>00358
<a name="l00359"></a>00359 <span class="comment">// skip past exponent bits because we don't know the value yet</span>
<a name="l00360"></a>00360 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> mask = 0x40;
<a name="l00361"></a>00361 <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> n = num_exp_bits; n > 0; --n) {
<a name="l00362"></a>00362 <span class="keywordflow">if</span> (n >= 8) {
<a name="l00363"></a>00363 ++ptr;
<a name="l00364"></a>00364 n -= 7;
<a name="l00365"></a>00365 } <span class="keywordflow">else</span> {
<a name="l00366"></a>00366 SHIFT_BITMASK(ptr, mask);
<a name="l00367"></a>00367 }
<a name="l00368"></a>00368 }
<a name="l00369"></a>00369
<a name="l00370"></a>00370 <span class="comment">// serialize fractional value < 1.0</span>
<a name="l00371"></a>00371 <span class="keywordtype">bool</span> got_exponent = <span class="keyword">false</span>;
<a name="l00372"></a>00372 boost::uint16_t num_bits = 0;
<a name="l00373"></a>00373 <span class="keywordflow">while</span> (value && num_bits < num_fraction_bits) {
<a name="l00374"></a>00374 value *= 2;
<a name="l00375"></a>00375 <span class="keywordflow">if</span> (got_exponent) {
<a name="l00376"></a>00376 <span class="keywordflow">if</span> (value >= 1.0) {
<a name="l00377"></a>00377 *ptr |= mask;
<a name="l00378"></a>00378 value -= 1.0;
<a name="l00379"></a>00379 }
<a name="l00380"></a>00380 SHIFT_BITMASK(ptr, mask);
<a name="l00381"></a>00381 ++num_bits;
<a name="l00382"></a>00382 } <span class="keywordflow">else</span> {
<a name="l00383"></a>00383 --exponent;
<a name="l00384"></a>00384 <span class="keywordflow">if</span> (value >= 1.0) {
<a name="l00385"></a>00385 value -= 1.0;
<a name="l00386"></a>00386 got_exponent = <span class="keyword">true</span>;
<a name="l00387"></a>00387 }
<a name="l00388"></a>00388 }
<a name="l00389"></a>00389 }
<a name="l00390"></a>00390
<a name="l00391"></a>00391 <span class="comment">// normalize exponent.</span>
<a name="l00392"></a>00392 <span class="comment">// note: we should have a zero exponent if value == 0</span>
<a name="l00393"></a>00393 boost::int32_t high_bit = ::pow((<span class="keywordtype">long</span> double)2, (<span class="keywordtype">int</span>)(num_exp_bits - 1));
<a name="l00394"></a>00394 <span class="keywordflow">if</span> (got_exponent)
<a name="l00395"></a>00395 exponent += (high_bit - 1);
<a name="l00396"></a>00396 <span class="keywordflow">else</span>
<a name="l00397"></a>00397 exponent = 0;
<a name="l00398"></a>00398
<a name="l00399"></a>00399 <span class="comment">// serialize exponent bits</span>
<a name="l00400"></a>00400 ptr = buf;
<a name="l00401"></a>00401 mask = 0x80;
<a name="l00402"></a>00402 <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> n = 0; n < num_exp_bits; ++n) {
<a name="l00403"></a>00403 SHIFT_BITMASK(ptr, mask);
<a name="l00404"></a>00404 <span class="keywordflow">if</span> (exponent >= high_bit) {
<a name="l00405"></a>00405 *ptr |= mask;
<a name="l00406"></a>00406 exponent -= high_bit;
<a name="l00407"></a>00407 }
<a name="l00408"></a>00408 high_bit /= 2;
<a name="l00409"></a>00409 }
<a name="l00410"></a>00410 }
<a name="l00411"></a>00411
<a name="l00412"></a>00412 } <span class="comment">// end namespace pion</span>
</pre></div></div>
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