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| <pre><span class="sourceLineNo">001</span>/**<a name="line.1"></a> |
| <span class="sourceLineNo">002</span> *<a name="line.2"></a> |
| <span class="sourceLineNo">003</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.3"></a> |
| <span class="sourceLineNo">004</span> * or more contributor license agreements. See the NOTICE file<a name="line.4"></a> |
| <span class="sourceLineNo">005</span> * distributed with this work for additional information<a name="line.5"></a> |
| <span class="sourceLineNo">006</span> * regarding copyright ownership. The ASF licenses this file<a name="line.6"></a> |
| <span class="sourceLineNo">007</span> * to you under the Apache License, Version 2.0 (the<a name="line.7"></a> |
| <span class="sourceLineNo">008</span> * "License"); you may not use this file except in compliance<a name="line.8"></a> |
| <span class="sourceLineNo">009</span> * with the License. You may obtain a copy of the License at<a name="line.9"></a> |
| <span class="sourceLineNo">010</span> *<a name="line.10"></a> |
| <span class="sourceLineNo">011</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.11"></a> |
| <span class="sourceLineNo">012</span> *<a name="line.12"></a> |
| <span class="sourceLineNo">013</span> * Unless required by applicable law or agreed to in writing, software<a name="line.13"></a> |
| <span class="sourceLineNo">014</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.14"></a> |
| <span class="sourceLineNo">015</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.15"></a> |
| <span class="sourceLineNo">016</span> * See the License for the specific language governing permissions and<a name="line.16"></a> |
| <span class="sourceLineNo">017</span> * limitations under the License.<a name="line.17"></a> |
| <span class="sourceLineNo">018</span> */<a name="line.18"></a> |
| <span class="sourceLineNo">019</span><a name="line.19"></a> |
| <span class="sourceLineNo">020</span>package org.apache.hadoop.hbase.util;<a name="line.20"></a> |
| <span class="sourceLineNo">021</span><a name="line.21"></a> |
| <span class="sourceLineNo">022</span>import static java.lang.Integer.rotateLeft;<a name="line.22"></a> |
| <span class="sourceLineNo">023</span><a name="line.23"></a> |
| <span class="sourceLineNo">024</span>import java.io.FileInputStream;<a name="line.24"></a> |
| <span class="sourceLineNo">025</span>import java.io.IOException;<a name="line.25"></a> |
| <span class="sourceLineNo">026</span><a name="line.26"></a> |
| <span class="sourceLineNo">027</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.27"></a> |
| <span class="sourceLineNo">028</span>import org.apache.yetus.audience.InterfaceStability;<a name="line.28"></a> |
| <span class="sourceLineNo">029</span><a name="line.29"></a> |
| <span class="sourceLineNo">030</span>/**<a name="line.30"></a> |
| <span class="sourceLineNo">031</span> * Produces 32-bit hash for hash table lookup.<a name="line.31"></a> |
| <span class="sourceLineNo">032</span> *<a name="line.32"></a> |
| <span class="sourceLineNo">033</span> * <pre>lookup3.c, by Bob Jenkins, May 2006, Public Domain.<a name="line.33"></a> |
| <span class="sourceLineNo">034</span> *<a name="line.34"></a> |
| <span class="sourceLineNo">035</span> * You can use this free for any purpose. It's in the public domain.<a name="line.35"></a> |
| <span class="sourceLineNo">036</span> * It has no warranty.<a name="line.36"></a> |
| <span class="sourceLineNo">037</span> * </pre><a name="line.37"></a> |
| <span class="sourceLineNo">038</span> *<a name="line.38"></a> |
| <span class="sourceLineNo">039</span> * @see <a href="http://burtleburtle.net/bob/c/lookup3.c">lookup3.c</a><a name="line.39"></a> |
| <span class="sourceLineNo">040</span> * @see <a href="http://www.ddj.com/184410284">Hash Functions (and how this<a name="line.40"></a> |
| <span class="sourceLineNo">041</span> * function compares to others such as CRC, MD?, etc</a><a name="line.41"></a> |
| <span class="sourceLineNo">042</span> * @see <a href="http://burtleburtle.net/bob/hash/doobs.html">Has update on the<a name="line.42"></a> |
| <span class="sourceLineNo">043</span> * Dr. Dobbs Article</a><a name="line.43"></a> |
| <span class="sourceLineNo">044</span> */<a name="line.44"></a> |
| <span class="sourceLineNo">045</span>@InterfaceAudience.Private<a name="line.45"></a> |
| <span class="sourceLineNo">046</span>@InterfaceStability.Stable<a name="line.46"></a> |
| <span class="sourceLineNo">047</span>public class JenkinsHash extends Hash {<a name="line.47"></a> |
| <span class="sourceLineNo">048</span> private static final int BYTE_MASK = 0xff;<a name="line.48"></a> |
| <span class="sourceLineNo">049</span><a name="line.49"></a> |
| <span class="sourceLineNo">050</span> private static JenkinsHash _instance = new JenkinsHash();<a name="line.50"></a> |
| <span class="sourceLineNo">051</span><a name="line.51"></a> |
| <span class="sourceLineNo">052</span> public static Hash getInstance() {<a name="line.52"></a> |
| <span class="sourceLineNo">053</span> return _instance;<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> }<a name="line.54"></a> |
| <span class="sourceLineNo">055</span><a name="line.55"></a> |
| <span class="sourceLineNo">056</span> /**<a name="line.56"></a> |
| <span class="sourceLineNo">057</span> * Compute the hash of the specified file<a name="line.57"></a> |
| <span class="sourceLineNo">058</span> * @param args name of file to compute hash of.<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> * @throws IOException e<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> */<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> public static void main(String[] args) throws IOException {<a name="line.61"></a> |
| <span class="sourceLineNo">062</span> if (args.length != 1) {<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> System.err.println("Usage: JenkinsHash filename");<a name="line.63"></a> |
| <span class="sourceLineNo">064</span> System.exit(-1);<a name="line.64"></a> |
| <span class="sourceLineNo">065</span> }<a name="line.65"></a> |
| <span class="sourceLineNo">066</span> FileInputStream in = new FileInputStream(args[0]);<a name="line.66"></a> |
| <span class="sourceLineNo">067</span> byte[] bytes = new byte[512];<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> int value = 0;<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> JenkinsHash hash = new JenkinsHash();<a name="line.69"></a> |
| <span class="sourceLineNo">070</span> try {<a name="line.70"></a> |
| <span class="sourceLineNo">071</span> for (int length = in.read(bytes); length > 0; length = in.read(bytes)) {<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> value = hash.hash(new ByteArrayHashKey(bytes, 0, length), value);<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> }<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> } finally {<a name="line.74"></a> |
| <span class="sourceLineNo">075</span> in.close();<a name="line.75"></a> |
| <span class="sourceLineNo">076</span> }<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> System.out.println(Math.abs(value));<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> }<a name="line.78"></a> |
| <span class="sourceLineNo">079</span><a name="line.79"></a> |
| <span class="sourceLineNo">080</span> /**<a name="line.80"></a> |
| <span class="sourceLineNo">081</span> * taken from hashlittle() -- hash a variable-length key into a 32-bit value<a name="line.81"></a> |
| <span class="sourceLineNo">082</span> *<a name="line.82"></a> |
| <span class="sourceLineNo">083</span> * @param hashKey the key to extract the bytes for hash algo<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> * @param initval can be any integer value<a name="line.84"></a> |
| <span class="sourceLineNo">085</span> * @return a 32-bit value. Every bit of the key affects every bit of the<a name="line.85"></a> |
| <span class="sourceLineNo">086</span> * return value. Two keys differing by one or two bits will have totally<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> * different hash values.<a name="line.87"></a> |
| <span class="sourceLineNo">088</span> *<a name="line.88"></a> |
| <span class="sourceLineNo">089</span> * <p>The best hash table sizes are powers of 2. There is no need to do mod<a name="line.89"></a> |
| <span class="sourceLineNo">090</span> * a prime (mod is sooo slow!). If you need less than 32 bits, use a bitmask.<a name="line.90"></a> |
| <span class="sourceLineNo">091</span> * For example, if you need only 10 bits, do<a name="line.91"></a> |
| <span class="sourceLineNo">092</span> * <code>h = (h &amp; hashmask(10));</code><a name="line.92"></a> |
| <span class="sourceLineNo">093</span> * In which case, the hash table should have hashsize(10) elements.<a name="line.93"></a> |
| <span class="sourceLineNo">094</span> *<a name="line.94"></a> |
| <span class="sourceLineNo">095</span> * <p>If you are hashing n strings byte[][] k, do it like this:<a name="line.95"></a> |
| <span class="sourceLineNo">096</span> * for (int i = 0, h = 0; i &lt; n; ++i) h = hash( k[i], h);<a name="line.96"></a> |
| <span class="sourceLineNo">097</span> *<a name="line.97"></a> |
| <span class="sourceLineNo">098</span> * <p>By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this<a name="line.98"></a> |
| <span class="sourceLineNo">099</span> * code any way you wish, private, educational, or commercial. It's free.<a name="line.99"></a> |
| <span class="sourceLineNo">100</span> *<a name="line.100"></a> |
| <span class="sourceLineNo">101</span> * <p>Use for hash table lookup, or anything where one collision in 2^^32 is<a name="line.101"></a> |
| <span class="sourceLineNo">102</span> * acceptable. Do NOT use for cryptographic purposes.<a name="line.102"></a> |
| <span class="sourceLineNo">103</span> */<a name="line.103"></a> |
| <span class="sourceLineNo">104</span> @SuppressWarnings({"fallthrough", "MissingDefault"})<a name="line.104"></a> |
| <span class="sourceLineNo">105</span> @Override<a name="line.105"></a> |
| <span class="sourceLineNo">106</span> public <T> int hash(HashKey<T> hashKey, int initval) {<a name="line.106"></a> |
| <span class="sourceLineNo">107</span> int length = hashKey.length();<a name="line.107"></a> |
| <span class="sourceLineNo">108</span> int a, b, c;<a name="line.108"></a> |
| <span class="sourceLineNo">109</span> a = b = c = 0xdeadbeef + length + initval;<a name="line.109"></a> |
| <span class="sourceLineNo">110</span> int offset = 0;<a name="line.110"></a> |
| <span class="sourceLineNo">111</span> for (; length > 12; offset += 12, length -= 12) {<a name="line.111"></a> |
| <span class="sourceLineNo">112</span> a += (hashKey.get(offset) & BYTE_MASK);<a name="line.112"></a> |
| <span class="sourceLineNo">113</span> a += ((hashKey.get(offset + 1) & BYTE_MASK) << 8);<a name="line.113"></a> |
| <span class="sourceLineNo">114</span> a += ((hashKey.get(offset + 2) & BYTE_MASK) << 16);<a name="line.114"></a> |
| <span class="sourceLineNo">115</span> a += ((hashKey.get(offset + 3) & BYTE_MASK) << 24);<a name="line.115"></a> |
| <span class="sourceLineNo">116</span> b += (hashKey.get(offset + 4) & BYTE_MASK);<a name="line.116"></a> |
| <span class="sourceLineNo">117</span> b += ((hashKey.get(offset + 5) & BYTE_MASK) << 8);<a name="line.117"></a> |
| <span class="sourceLineNo">118</span> b += ((hashKey.get(offset + 6) & BYTE_MASK) << 16);<a name="line.118"></a> |
| <span class="sourceLineNo">119</span> b += ((hashKey.get(offset + 7) & BYTE_MASK) << 24);<a name="line.119"></a> |
| <span class="sourceLineNo">120</span> c += (hashKey.get(offset + 8) & BYTE_MASK);<a name="line.120"></a> |
| <span class="sourceLineNo">121</span> c += ((hashKey.get(offset + 9) & BYTE_MASK) << 8);<a name="line.121"></a> |
| <span class="sourceLineNo">122</span> c += ((hashKey.get(offset + 10) & BYTE_MASK) << 16);<a name="line.122"></a> |
| <span class="sourceLineNo">123</span> c += ((hashKey.get(offset + 11) & BYTE_MASK) << 24);<a name="line.123"></a> |
| <span class="sourceLineNo">124</span><a name="line.124"></a> |
| <span class="sourceLineNo">125</span> /*<a name="line.125"></a> |
| <span class="sourceLineNo">126</span> * mix -- mix 3 32-bit values reversibly.<a name="line.126"></a> |
| <span class="sourceLineNo">127</span> * This is reversible, so any information in (a,b,c) before mix() is<a name="line.127"></a> |
| <span class="sourceLineNo">128</span> * still in (a,b,c) after mix().<a name="line.128"></a> |
| <span class="sourceLineNo">129</span> *<a name="line.129"></a> |
| <span class="sourceLineNo">130</span> * If four pairs of (a,b,c) inputs are run through mix(), or through<a name="line.130"></a> |
| <span class="sourceLineNo">131</span> * mix() in reverse, there are at least 32 bits of the output that<a name="line.131"></a> |
| <span class="sourceLineNo">132</span> * are sometimes the same for one pair and different for another pair.<a name="line.132"></a> |
| <span class="sourceLineNo">133</span> *<a name="line.133"></a> |
| <span class="sourceLineNo">134</span> * This was tested for:<a name="line.134"></a> |
| <span class="sourceLineNo">135</span> * - pairs that differed by one bit, by two bits, in any combination<a name="line.135"></a> |
| <span class="sourceLineNo">136</span> * of top bits of (a,b,c), or in any combination of bottom bits of<a name="line.136"></a> |
| <span class="sourceLineNo">137</span> * (a,b,c).<a name="line.137"></a> |
| <span class="sourceLineNo">138</span> * - "differ" is defined as +, -, ^, or ~^. For + and -, I transformed<a name="line.138"></a> |
| <span class="sourceLineNo">139</span> * the output delta to a Gray code (a^(a>>1)) so a string of 1's (as<a name="line.139"></a> |
| <span class="sourceLineNo">140</span> * is commonly produced by subtraction) look like a single 1-bit<a name="line.140"></a> |
| <span class="sourceLineNo">141</span> * difference.<a name="line.141"></a> |
| <span class="sourceLineNo">142</span> * - the base values were pseudorandom, all zero but one bit set, or<a name="line.142"></a> |
| <span class="sourceLineNo">143</span> * all zero plus a counter that starts at zero.<a name="line.143"></a> |
| <span class="sourceLineNo">144</span> *<a name="line.144"></a> |
| <span class="sourceLineNo">145</span> * Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that<a name="line.145"></a> |
| <span class="sourceLineNo">146</span> * satisfy this are<a name="line.146"></a> |
| <span class="sourceLineNo">147</span> * 4 6 8 16 19 4<a name="line.147"></a> |
| <span class="sourceLineNo">148</span> * 9 15 3 18 27 15<a name="line.148"></a> |
| <span class="sourceLineNo">149</span> * 14 9 3 7 17 3<a name="line.149"></a> |
| <span class="sourceLineNo">150</span> * Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing for<a name="line.150"></a> |
| <span class="sourceLineNo">151</span> * "differ" defined as + with a one-bit base and a two-bit delta. I<a name="line.151"></a> |
| <span class="sourceLineNo">152</span> * used http://burtleburtle.net/bob/hash/avalanche.html to choose<a name="line.152"></a> |
| <span class="sourceLineNo">153</span> * the operations, constants, and arrangements of the variables.<a name="line.153"></a> |
| <span class="sourceLineNo">154</span> *<a name="line.154"></a> |
| <span class="sourceLineNo">155</span> * This does not achieve avalanche. There are input bits of (a,b,c)<a name="line.155"></a> |
| <span class="sourceLineNo">156</span> * that fail to affect some output bits of (a,b,c), especially of a.<a name="line.156"></a> |
| <span class="sourceLineNo">157</span> * The most thoroughly mixed value is c, but it doesn't really even<a name="line.157"></a> |
| <span class="sourceLineNo">158</span> * achieve avalanche in c.<a name="line.158"></a> |
| <span class="sourceLineNo">159</span> *<a name="line.159"></a> |
| <span class="sourceLineNo">160</span> * This allows some parallelism. Read-after-writes are good at doubling<a name="line.160"></a> |
| <span class="sourceLineNo">161</span> * the number of bits affected, so the goal of mixing pulls in the<a name="line.161"></a> |
| <span class="sourceLineNo">162</span> * opposite direction as the goal of parallelism. I did what I could.<a name="line.162"></a> |
| <span class="sourceLineNo">163</span> * Rotates seem to cost as much as shifts on every machine I could lay<a name="line.163"></a> |
| <span class="sourceLineNo">164</span> * my hands on, and rotates are much kinder to the top and bottom bits,<a name="line.164"></a> |
| <span class="sourceLineNo">165</span> * so I used rotates.<a name="line.165"></a> |
| <span class="sourceLineNo">166</span> *<a name="line.166"></a> |
| <span class="sourceLineNo">167</span> * #define mix(a,b,c) \<a name="line.167"></a> |
| <span class="sourceLineNo">168</span> * { \<a name="line.168"></a> |
| <span class="sourceLineNo">169</span> * a -= c; a ^= rot(c, 4); c += b; \<a name="line.169"></a> |
| <span class="sourceLineNo">170</span> * b -= a; b ^= rot(a, 6); a += c; \<a name="line.170"></a> |
| <span class="sourceLineNo">171</span> * c -= b; c ^= rot(b, 8); b += a; \<a name="line.171"></a> |
| <span class="sourceLineNo">172</span> * a -= c; a ^= rot(c,16); c += b; \<a name="line.172"></a> |
| <span class="sourceLineNo">173</span> * b -= a; b ^= rot(a,19); a += c; \<a name="line.173"></a> |
| <span class="sourceLineNo">174</span> * c -= b; c ^= rot(b, 4); b += a; \<a name="line.174"></a> |
| <span class="sourceLineNo">175</span> * }<a name="line.175"></a> |
| <span class="sourceLineNo">176</span> *<a name="line.176"></a> |
| <span class="sourceLineNo">177</span> * mix(a,b,c);<a name="line.177"></a> |
| <span class="sourceLineNo">178</span> */<a name="line.178"></a> |
| <span class="sourceLineNo">179</span> a -= c; a ^= rotateLeft(c, 4); c += b;<a name="line.179"></a> |
| <span class="sourceLineNo">180</span> b -= a; b ^= rotateLeft(a, 6); a += c;<a name="line.180"></a> |
| <span class="sourceLineNo">181</span> c -= b; c ^= rotateLeft(b, 8); b += a;<a name="line.181"></a> |
| <span class="sourceLineNo">182</span> a -= c; a ^= rotateLeft(c, 16); c += b;<a name="line.182"></a> |
| <span class="sourceLineNo">183</span> b -= a; b ^= rotateLeft(a, 19); a += c;<a name="line.183"></a> |
| <span class="sourceLineNo">184</span> c -= b; c ^= rotateLeft(b, 4); b += a;<a name="line.184"></a> |
| <span class="sourceLineNo">185</span> }<a name="line.185"></a> |
| <span class="sourceLineNo">186</span><a name="line.186"></a> |
| <span class="sourceLineNo">187</span> //-------------------------------- last block: affect all 32 bits of (c)<a name="line.187"></a> |
| <span class="sourceLineNo">188</span> switch (length) { // all the case statements fall through<a name="line.188"></a> |
| <span class="sourceLineNo">189</span> case 12:<a name="line.189"></a> |
| <span class="sourceLineNo">190</span> c += ((hashKey.get(offset + 11) & BYTE_MASK) << 24);<a name="line.190"></a> |
| <span class="sourceLineNo">191</span> case 11:<a name="line.191"></a> |
| <span class="sourceLineNo">192</span> c += ((hashKey.get(offset + 10) & BYTE_MASK) << 16);<a name="line.192"></a> |
| <span class="sourceLineNo">193</span> case 10:<a name="line.193"></a> |
| <span class="sourceLineNo">194</span> c += ((hashKey.get(offset + 9) & BYTE_MASK) << 8);<a name="line.194"></a> |
| <span class="sourceLineNo">195</span> case 9:<a name="line.195"></a> |
| <span class="sourceLineNo">196</span> c += (hashKey.get(offset + 8) & BYTE_MASK);<a name="line.196"></a> |
| <span class="sourceLineNo">197</span> case 8:<a name="line.197"></a> |
| <span class="sourceLineNo">198</span> b += ((hashKey.get(offset + 7) & BYTE_MASK) << 24);<a name="line.198"></a> |
| <span class="sourceLineNo">199</span> case 7:<a name="line.199"></a> |
| <span class="sourceLineNo">200</span> b += ((hashKey.get(offset + 6) & BYTE_MASK) << 16);<a name="line.200"></a> |
| <span class="sourceLineNo">201</span> case 6:<a name="line.201"></a> |
| <span class="sourceLineNo">202</span> b += ((hashKey.get(offset + 5) & BYTE_MASK) << 8);<a name="line.202"></a> |
| <span class="sourceLineNo">203</span> case 5:<a name="line.203"></a> |
| <span class="sourceLineNo">204</span> b += (hashKey.get(offset + 4) & BYTE_MASK);<a name="line.204"></a> |
| <span class="sourceLineNo">205</span> case 4:<a name="line.205"></a> |
| <span class="sourceLineNo">206</span> a += ((hashKey.get(offset + 3) & BYTE_MASK) << 24);<a name="line.206"></a> |
| <span class="sourceLineNo">207</span> case 3:<a name="line.207"></a> |
| <span class="sourceLineNo">208</span> a += ((hashKey.get(offset + 2) & BYTE_MASK) << 16);<a name="line.208"></a> |
| <span class="sourceLineNo">209</span> case 2:<a name="line.209"></a> |
| <span class="sourceLineNo">210</span> a += ((hashKey.get(offset + 1) & BYTE_MASK) << 8);<a name="line.210"></a> |
| <span class="sourceLineNo">211</span> case 1:<a name="line.211"></a> |
| <span class="sourceLineNo">212</span> //noinspection PointlessArithmeticExpression<a name="line.212"></a> |
| <span class="sourceLineNo">213</span> a += (hashKey.get(offset + 0) & BYTE_MASK);<a name="line.213"></a> |
| <span class="sourceLineNo">214</span> break;<a name="line.214"></a> |
| <span class="sourceLineNo">215</span> case 0:<a name="line.215"></a> |
| <span class="sourceLineNo">216</span> return c;<a name="line.216"></a> |
| <span class="sourceLineNo">217</span> }<a name="line.217"></a> |
| <span class="sourceLineNo">218</span> /*<a name="line.218"></a> |
| <span class="sourceLineNo">219</span> * final -- final mixing of 3 32-bit values (a,b,c) into c<a name="line.219"></a> |
| <span class="sourceLineNo">220</span> *<a name="line.220"></a> |
| <span class="sourceLineNo">221</span> * Pairs of (a,b,c) values differing in only a few bits will usually<a name="line.221"></a> |
| <span class="sourceLineNo">222</span> * produce values of c that look totally different. This was tested for<a name="line.222"></a> |
| <span class="sourceLineNo">223</span> * - pairs that differed by one bit, by two bits, in any combination<a name="line.223"></a> |
| <span class="sourceLineNo">224</span> * of top bits of (a,b,c), or in any combination of bottom bits of<a name="line.224"></a> |
| <span class="sourceLineNo">225</span> * (a,b,c).<a name="line.225"></a> |
| <span class="sourceLineNo">226</span> *<a name="line.226"></a> |
| <span class="sourceLineNo">227</span> * - "differ" is defined as +, -, ^, or ~^. For + and -, I transformed<a name="line.227"></a> |
| <span class="sourceLineNo">228</span> * the output delta to a Gray code (a^(a>>1)) so a string of 1's (as<a name="line.228"></a> |
| <span class="sourceLineNo">229</span> * is commonly produced by subtraction) look like a single 1-bit<a name="line.229"></a> |
| <span class="sourceLineNo">230</span> * difference.<a name="line.230"></a> |
| <span class="sourceLineNo">231</span> *<a name="line.231"></a> |
| <span class="sourceLineNo">232</span> * - the base values were pseudorandom, all zero but one bit set, or<a name="line.232"></a> |
| <span class="sourceLineNo">233</span> * all zero plus a counter that starts at zero.<a name="line.233"></a> |
| <span class="sourceLineNo">234</span> *<a name="line.234"></a> |
| <span class="sourceLineNo">235</span> * These constants passed:<a name="line.235"></a> |
| <span class="sourceLineNo">236</span> * 14 11 25 16 4 14 24<a name="line.236"></a> |
| <span class="sourceLineNo">237</span> * 12 14 25 16 4 14 24<a name="line.237"></a> |
| <span class="sourceLineNo">238</span> * and these came close:<a name="line.238"></a> |
| <span class="sourceLineNo">239</span> * 4 8 15 26 3 22 24<a name="line.239"></a> |
| <span class="sourceLineNo">240</span> * 10 8 15 26 3 22 24<a name="line.240"></a> |
| <span class="sourceLineNo">241</span> * 11 8 15 26 3 22 24<a name="line.241"></a> |
| <span class="sourceLineNo">242</span> *<a name="line.242"></a> |
| <span class="sourceLineNo">243</span> * #define final(a,b,c) \<a name="line.243"></a> |
| <span class="sourceLineNo">244</span> * {<a name="line.244"></a> |
| <span class="sourceLineNo">245</span> * c ^= b; c -= rot(b,14); \<a name="line.245"></a> |
| <span class="sourceLineNo">246</span> * a ^= c; a -= rot(c,11); \<a name="line.246"></a> |
| <span class="sourceLineNo">247</span> * b ^= a; b -= rot(a,25); \<a name="line.247"></a> |
| <span class="sourceLineNo">248</span> * c ^= b; c -= rot(b,16); \<a name="line.248"></a> |
| <span class="sourceLineNo">249</span> * a ^= c; a -= rot(c,4); \<a name="line.249"></a> |
| <span class="sourceLineNo">250</span> * b ^= a; b -= rot(a,14); \<a name="line.250"></a> |
| <span class="sourceLineNo">251</span> * c ^= b; c -= rot(b,24); \<a name="line.251"></a> |
| <span class="sourceLineNo">252</span> * }<a name="line.252"></a> |
| <span class="sourceLineNo">253</span> *<a name="line.253"></a> |
| <span class="sourceLineNo">254</span> */<a name="line.254"></a> |
| <span class="sourceLineNo">255</span> c ^= b; c -= rotateLeft(b, 14);<a name="line.255"></a> |
| <span class="sourceLineNo">256</span> a ^= c; a -= rotateLeft(c, 11);<a name="line.256"></a> |
| <span class="sourceLineNo">257</span> b ^= a; b -= rotateLeft(a, 25);<a name="line.257"></a> |
| <span class="sourceLineNo">258</span> c ^= b; c -= rotateLeft(b, 16);<a name="line.258"></a> |
| <span class="sourceLineNo">259</span> a ^= c; a -= rotateLeft(c, 4);<a name="line.259"></a> |
| <span class="sourceLineNo">260</span> b ^= a; b -= rotateLeft(a, 14);<a name="line.260"></a> |
| <span class="sourceLineNo">261</span> c ^= b; c -= rotateLeft(b, 24);<a name="line.261"></a> |
| <span class="sourceLineNo">262</span> return c;<a name="line.262"></a> |
| <span class="sourceLineNo">263</span> }<a name="line.263"></a> |
| <span class="sourceLineNo">264</span>}<a name="line.264"></a> |
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| </pre> |
| </div> |
| </body> |
| </html> |