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| <div class="title">SmallFloat.cs</div> </div> |
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| <div class="contents"> |
| <a href="_small_float_8cs.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/* </span></div> |
| <div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment"> * Licensed to the Apache Software Foundation (ASF) under one or more</span></div> |
| <div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment"> * contributor license agreements. See the NOTICE file distributed with</span></div> |
| <div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment"> * this work for additional information regarding copyright ownership.</span></div> |
| <div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment"> * The ASF licenses this file to You under the Apache License, Version 2.0</span></div> |
| <div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"> * (the "License"); you may not use this file except in compliance with</span></div> |
| <div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"> * the License. You may obtain a copy of the License at</span></div> |
| <div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment"> * </span></div> |
| <div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment"> * http://www.apache.org/licenses/LICENSE-2.0</span></div> |
| <div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment"> * </span></div> |
| <div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment"> * Unless required by applicable law or agreed to in writing, software</span></div> |
| <div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment"> * distributed under the License is distributed on an "AS IS" BASIS,</span></div> |
| <div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span></div> |
| <div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment"> * See the License for the specific language governing permissions and</span></div> |
| <div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment"> * limitations under the License.</span></div> |
| <div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00017"></a><span class="lineno"> 17</span> </div> |
| <div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="keyword">using</span> System;</div> |
| <div class="line"><a name="l00019"></a><span class="lineno"> 19</span> </div> |
| <div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="keyword">namespace </span>Lucene.Net.Util</div> |
| <div class="line"><a name="l00021"></a><span class="lineno"> 21</span> {</div> |
| <div class="line"><a name="l00022"></a><span class="lineno"> 22</span>  </div> |
| <div class="line"><a name="l00023"></a><span class="lineno"> 23</span>  </div> |
| <div class="line"><a name="l00029"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html"> 29</a></span>  <span class="keyword">public</span> <span class="keyword">class </span><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html" title="Floating point numbers smaller than 32 bits.">SmallFloat</a></div> |
| <div class="line"><a name="l00030"></a><span class="lineno"> 30</span>  {</div> |
| <div class="line"><a name="l00031"></a><span class="lineno"> 31</span>  </div> |
| <div class="line"><a name="l00047"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a2005feda9230e0b7298f22b546abb971"> 47</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> sbyte FloatToByte(<span class="keywordtype">float</span> f, <span class="keywordtype">int</span> numMantissaBits, <span class="keywordtype">int</span> zeroExp)</div> |
| <div class="line"><a name="l00048"></a><span class="lineno"> 48</span>  {</div> |
| <div class="line"><a name="l00049"></a><span class="lineno"> 49</span>  <span class="comment">// Adjustment from a float zero exponent to our zero exponent,</span></div> |
| <div class="line"><a name="l00050"></a><span class="lineno"> 50</span>  <span class="comment">// shifted over to our exponent position.</span></div> |
| <div class="line"><a name="l00051"></a><span class="lineno"> 51</span>  <span class="keywordtype">int</span> fzero = (63 - zeroExp) << numMantissaBits;</div> |
| <div class="line"><a name="l00052"></a><span class="lineno"> 52</span>  <span class="keywordtype">int</span> bits = System.BitConverter.ToInt32(System.BitConverter.GetBytes(f), 0);</div> |
| <div class="line"><a name="l00053"></a><span class="lineno"> 53</span>  <span class="keywordtype">int</span> smallfloat = bits >> (24 - numMantissaBits);</div> |
| <div class="line"><a name="l00054"></a><span class="lineno"> 54</span>  <span class="keywordflow">if</span> (smallfloat < fzero)</div> |
| <div class="line"><a name="l00055"></a><span class="lineno"> 55</span>  {</div> |
| <div class="line"><a name="l00056"></a><span class="lineno"> 56</span>  <span class="keywordflow">return</span> (bits <= 0)?(sbyte) 0:(sbyte) 1; <span class="comment">// underflow is mapped to smallest non-zero number.</span></div> |
| <div class="line"><a name="l00057"></a><span class="lineno"> 57</span>  }</div> |
| <div class="line"><a name="l00058"></a><span class="lineno"> 58</span>  <span class="keywordflow">else</span> <span class="keywordflow">if</span> (smallfloat >= fzero + 0x100)</div> |
| <div class="line"><a name="l00059"></a><span class="lineno"> 59</span>  {</div> |
| <div class="line"><a name="l00060"></a><span class="lineno"> 60</span>  <span class="keywordflow">return</span> - 1; <span class="comment">// overflow maps to largest number</span></div> |
| <div class="line"><a name="l00061"></a><span class="lineno"> 61</span>  }</div> |
| <div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  <span class="keywordflow">else</span></div> |
| <div class="line"><a name="l00063"></a><span class="lineno"> 63</span>  {</div> |
| <div class="line"><a name="l00064"></a><span class="lineno"> 64</span>  <span class="keywordflow">return</span> (sbyte) (smallfloat - fzero);</div> |
| <div class="line"><a name="l00065"></a><span class="lineno"> 65</span>  }</div> |
| <div class="line"><a name="l00066"></a><span class="lineno"> 66</span>  }</div> |
| <div class="line"><a name="l00067"></a><span class="lineno"> 67</span>  </div> |
| <div class="line"><a name="l00069"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a78e659be3bd6157edb4c35f49b242c7d"> 69</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> <span class="keywordtype">float</span> ByteToFloat(byte b, <span class="keywordtype">int</span> numMantissaBits, <span class="keywordtype">int</span> zeroExp)</div> |
| <div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  {</div> |
| <div class="line"><a name="l00071"></a><span class="lineno"> 71</span>  <span class="comment">// on Java1.5 & 1.6 JVMs, prebuilding a decoding array and doing a lookup</span></div> |
| <div class="line"><a name="l00072"></a><span class="lineno"> 72</span>  <span class="comment">// is only a little bit faster (anywhere from 0% to 7%)</span></div> |
| <div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  <span class="keywordflow">if</span> (b == 0)</div> |
| <div class="line"><a name="l00074"></a><span class="lineno"> 74</span>  <span class="keywordflow">return</span> 0.0f;</div> |
| <div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  <span class="keywordtype">int</span> bits = (b & 0xff) << (24 - numMantissaBits);</div> |
| <div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  bits += ((63 - zeroExp) << 24);</div> |
| <div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  <span class="keywordflow">return</span> BitConverter.ToSingle(BitConverter.GetBytes(bits), 0);</div> |
| <div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  }</div> |
| <div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  </div> |
| <div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  </div> |
| <div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  <span class="comment">//</span></div> |
| <div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  <span class="comment">// Some specializations of the generic functions follow.</span></div> |
| <div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  <span class="comment">// The generic functions are just as fast with current (1.5)</span></div> |
| <div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  <span class="comment">// -server JVMs, but still slower with client JVMs.</span></div> |
| <div class="line"><a name="l00085"></a><span class="lineno"> 85</span>  <span class="comment">//</span></div> |
| <div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  </div> |
| <div class="line"><a name="l00092"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a6bf32abe2058e30ba9fa3a3593f1dd90"> 92</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> sbyte FloatToByte315(<span class="keywordtype">float</span> f)</div> |
| <div class="line"><a name="l00093"></a><span class="lineno"> 93</span>  {</div> |
| <div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  <span class="keywordtype">int</span> bits = System.BitConverter.ToInt32(System.BitConverter.GetBytes(f), 0);</div> |
| <div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  <span class="keywordtype">int</span> smallfloat = bits >> (24 - 3);</div> |
| <div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  <span class="keywordflow">if</span> (smallfloat < (63 - 15) << 3)</div> |
| <div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  {</div> |
| <div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  <span class="keywordflow">return</span> (bits <= 0)?(sbyte) 0:(sbyte) 1;</div> |
| <div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  }</div> |
| <div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  <span class="keywordflow">if</span> (smallfloat >= ((63 - 15) << 3) + 0x100)</div> |
| <div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  {</div> |
| <div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  <span class="keywordflow">return</span> - 1;</div> |
| <div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  }</div> |
| <div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  <span class="keywordflow">return</span> (sbyte) (smallfloat - ((63 - 15) << 3));</div> |
| <div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  }</div> |
| <div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  </div> |
| <div class="line"><a name="l00108"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a080e3cd4ea85b3a6f3eabe9a45da23eb"> 108</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> <span class="keywordtype">float</span> Byte315ToFloat(byte b)</div> |
| <div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  {</div> |
| <div class="line"><a name="l00110"></a><span class="lineno"> 110</span>  <span class="comment">// on Java1.5 & 1.6 JVMs, prebuilding a decoding array and doing a lookup</span></div> |
| <div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="comment">// is only a little bit faster (anywhere from 0% to 7%)</span></div> |
| <div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  <span class="keywordflow">if</span> (b == 0)</div> |
| <div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  <span class="keywordflow">return</span> 0.0f;</div> |
| <div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  <span class="keywordtype">int</span> bits = (b & 0xff) << (24 - 3);</div> |
| <div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  bits += ((63 - 15) << 24);</div> |
| <div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  <span class="keywordflow">return</span> BitConverter.ToSingle(BitConverter.GetBytes(bits), 0);</div> |
| <div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  }</div> |
| <div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  </div> |
| <div class="line"><a name="l00119"></a><span class="lineno"> 119</span>  </div> |
| <div class="line"><a name="l00125"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a455f6f4772f85f68a5c9fdc29f9fbc00"> 125</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> sbyte FloatToByte52(<span class="keywordtype">float</span> f)</div> |
| <div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  {</div> |
| <div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  <span class="keywordtype">int</span> bits = System.BitConverter.ToInt32(System.BitConverter.GetBytes(f), 0);</div> |
| <div class="line"><a name="l00128"></a><span class="lineno"> 128</span>  <span class="keywordtype">int</span> smallfloat = bits >> (24 - 5);</div> |
| <div class="line"><a name="l00129"></a><span class="lineno"> 129</span>  <span class="keywordflow">if</span> (smallfloat < (63 - 2) << 5)</div> |
| <div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  {</div> |
| <div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  <span class="keywordflow">return</span> (bits <= 0)?(sbyte) 0:(sbyte) 1;</div> |
| <div class="line"><a name="l00132"></a><span class="lineno"> 132</span>  }</div> |
| <div class="line"><a name="l00133"></a><span class="lineno"> 133</span>  <span class="keywordflow">if</span> (smallfloat >= ((63 - 2) << 5) + 0x100)</div> |
| <div class="line"><a name="l00134"></a><span class="lineno"> 134</span>  {</div> |
| <div class="line"><a name="l00135"></a><span class="lineno"> 135</span>  <span class="keywordflow">return</span> - 1;</div> |
| <div class="line"><a name="l00136"></a><span class="lineno"> 136</span>  }</div> |
| <div class="line"><a name="l00137"></a><span class="lineno"> 137</span>  <span class="keywordflow">return</span> (sbyte) (smallfloat - ((63 - 2) << 5));</div> |
| <div class="line"><a name="l00138"></a><span class="lineno"> 138</span>  }</div> |
| <div class="line"><a name="l00139"></a><span class="lineno"> 139</span>  </div> |
| <div class="line"><a name="l00141"></a><span class="lineno"><a class="code" href="class_lucene_1_1_net_1_1_util_1_1_small_float.html#a57517b4added3e11420d7e4f772f9330"> 141</a></span>  <span class="keyword">public</span> <span class="keyword">static</span> <span class="keywordtype">float</span> Byte52ToFloat(byte b)</div> |
| <div class="line"><a name="l00142"></a><span class="lineno"> 142</span>  {</div> |
| <div class="line"><a name="l00143"></a><span class="lineno"> 143</span>  <span class="comment">// on Java1.5 & 1.6 JVMs, prebuilding a decoding array and doing a lookup</span></div> |
| <div class="line"><a name="l00144"></a><span class="lineno"> 144</span>  <span class="comment">// is only a little bit faster (anywhere from 0% to 7%)</span></div> |
| <div class="line"><a name="l00145"></a><span class="lineno"> 145</span>  <span class="keywordflow">if</span> (b == 0)</div> |
| <div class="line"><a name="l00146"></a><span class="lineno"> 146</span>  <span class="keywordflow">return</span> 0.0f;</div> |
| <div class="line"><a name="l00147"></a><span class="lineno"> 147</span>  <span class="keywordtype">int</span> bits = (b & 0xff) << (24 - 5);</div> |
| <div class="line"><a name="l00148"></a><span class="lineno"> 148</span>  bits += ((63 - 2) << 24);</div> |
| <div class="line"><a name="l00149"></a><span class="lineno"> 149</span>  <span class="keywordflow">return</span> BitConverter.ToSingle(BitConverter.GetBytes(bits), 0);</div> |
| <div class="line"><a name="l00150"></a><span class="lineno"> 150</span>  }</div> |
| <div class="line"><a name="l00151"></a><span class="lineno"> 151</span>  }</div> |
| <div class="line"><a name="l00152"></a><span class="lineno"> 152</span> }</div> |
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