forked from I2P_Developers/i2p.i2p
40 lines
1.1 KiB
Java
40 lines
1.1 KiB
Java
package net.i2p.kademlia;
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import java.util.Comparator;
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import net.i2p.data.SimpleDataStructure;
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/**
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* Help sort Hashes in relation to a base key using the XOR metric
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*
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* @since 0.9.2
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*/
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class XORComparator<T extends SimpleDataStructure> implements Comparator<T> {
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private final byte[] _base;
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/**
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* @param target key to compare distances with
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*/
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public XORComparator(T target) {
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_base = target.getData();
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}
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public int compare(T lhs, T rhs) {
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// same as the following but byte-by-byte for efficiency
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//byte lhsDelta[] = DataHelper.xor(lhs.getData(), _base);
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//byte rhsDelta[] = DataHelper.xor(rhs.getData(), _base);
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//return DataHelper.compareTo(lhsDelta, rhsDelta);
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byte lhsb[] = lhs.getData();
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byte rhsb[] = rhs.getData();
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for (int i = 0; i < _base.length; i++) {
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int ld = (lhsb[i] ^ _base[i]) & 0xff;
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int rd = (rhsb[i] ^ _base[i]) & 0xff;
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if (ld < rd)
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return -1;
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if (ld > rd)
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return 1;
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}
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return 0;
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}
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}
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