mirror of https://github.com/apache/lucene.git
LUCENE-6374: remove unused BitUtil code
git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1671800 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Robert Muir
parent
344ce28214
commit
7beade85f4
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@ -22,93 +22,8 @@ package org.apache.lucene.util; // from org.apache.solr.util rev 555343
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*/
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public final class BitUtil {
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private static final byte[] BYTE_COUNTS = { // table of bits/byte
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0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
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};
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// The General Idea: instead of having an array per byte that has
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// the offsets of the next set bit, that array could be
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// packed inside a 32 bit integer (8 4 bit numbers). That
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// should be faster than accessing an array for each index, and
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// the total array size is kept smaller (256*sizeof(int))=1K
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/* the python code that generated bitlist
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def bits2int(val):
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arr=0
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for shift in range(8,0,-1):
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if val & 0x80:
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arr = (arr << 4) | shift
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val = val << 1
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return arr
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def int_table():
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tbl = [ hex(bits2int(val)).strip('L') for val in range(256) ]
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return ','.join(tbl)
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*/
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private static final int[] BIT_LISTS = {
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0x0, 0x1, 0x2, 0x21, 0x3, 0x31, 0x32, 0x321, 0x4, 0x41, 0x42, 0x421, 0x43,
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0x431, 0x432, 0x4321, 0x5, 0x51, 0x52, 0x521, 0x53, 0x531, 0x532, 0x5321,
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0x54, 0x541, 0x542, 0x5421, 0x543, 0x5431, 0x5432, 0x54321, 0x6, 0x61, 0x62,
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0x621, 0x63, 0x631, 0x632, 0x6321, 0x64, 0x641, 0x642, 0x6421, 0x643,
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0x6431, 0x6432, 0x64321, 0x65, 0x651, 0x652, 0x6521, 0x653, 0x6531, 0x6532,
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0x65321, 0x654, 0x6541, 0x6542, 0x65421, 0x6543, 0x65431, 0x65432, 0x654321,
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0x7, 0x71, 0x72, 0x721, 0x73, 0x731, 0x732, 0x7321, 0x74, 0x741, 0x742,
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0x7421, 0x743, 0x7431, 0x7432, 0x74321, 0x75, 0x751, 0x752, 0x7521, 0x753,
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0x7531, 0x7532, 0x75321, 0x754, 0x7541, 0x7542, 0x75421, 0x7543, 0x75431,
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0x75432, 0x754321, 0x76, 0x761, 0x762, 0x7621, 0x763, 0x7631, 0x7632,
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0x76321, 0x764, 0x7641, 0x7642, 0x76421, 0x7643, 0x76431, 0x76432, 0x764321,
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0x765, 0x7651, 0x7652, 0x76521, 0x7653, 0x76531, 0x76532, 0x765321, 0x7654,
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0x76541, 0x76542, 0x765421, 0x76543, 0x765431, 0x765432, 0x7654321, 0x8,
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0x81, 0x82, 0x821, 0x83, 0x831, 0x832, 0x8321, 0x84, 0x841, 0x842, 0x8421,
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0x843, 0x8431, 0x8432, 0x84321, 0x85, 0x851, 0x852, 0x8521, 0x853, 0x8531,
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0x8532, 0x85321, 0x854, 0x8541, 0x8542, 0x85421, 0x8543, 0x85431, 0x85432,
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0x854321, 0x86, 0x861, 0x862, 0x8621, 0x863, 0x8631, 0x8632, 0x86321, 0x864,
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0x8641, 0x8642, 0x86421, 0x8643, 0x86431, 0x86432, 0x864321, 0x865, 0x8651,
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0x8652, 0x86521, 0x8653, 0x86531, 0x86532, 0x865321, 0x8654, 0x86541,
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0x86542, 0x865421, 0x86543, 0x865431, 0x865432, 0x8654321, 0x87, 0x871,
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0x872, 0x8721, 0x873, 0x8731, 0x8732, 0x87321, 0x874, 0x8741, 0x8742,
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0x87421, 0x8743, 0x87431, 0x87432, 0x874321, 0x875, 0x8751, 0x8752, 0x87521,
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0x8753, 0x87531, 0x87532, 0x875321, 0x8754, 0x87541, 0x87542, 0x875421,
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0x87543, 0x875431, 0x875432, 0x8754321, 0x876, 0x8761, 0x8762, 0x87621,
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0x8763, 0x87631, 0x87632, 0x876321, 0x8764, 0x87641, 0x87642, 0x876421,
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0x87643, 0x876431, 0x876432, 0x8764321, 0x8765, 0x87651, 0x87652, 0x876521,
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0x87653, 0x876531, 0x876532, 0x8765321, 0x87654, 0x876541, 0x876542,
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0x8765421, 0x876543, 0x8765431, 0x8765432, 0x87654321
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};
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private BitUtil() {} // no instance
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/** Return the number of bits sets in b. */
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public static int bitCount(byte b) {
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return BYTE_COUNTS[b & 0xFF];
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}
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/** Return the list of bits which are set in b encoded as followed:
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* {@code (i >>> (4 * n)) & 0x0F} is the offset of the n-th set bit of
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* the given byte plus one, or 0 if there are n or less bits set in the given
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* byte. For example <code>bitList(12)</code> returns 0x43:<ul>
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* <li>{@code 0x43 & 0x0F} is 3, meaning the the first bit set is at offset 3-1 = 2,</li>
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* <li>{@code (0x43 >>> 4) & 0x0F} is 4, meaning there is a second bit set at offset 4-1=3,</li>
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* <li>{@code (0x43 >>> 8) & 0x0F} is 0, meaning there is no more bit set in this byte.</li>
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* </ul>*/
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public static int bitList(byte b) {
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return BIT_LISTS[b & 0xFF];
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}
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// The pop methods used to rely on bit-manipulation tricks for speed but it
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// turns out that it is faster to use the Long.bitCount method (which is an
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// intrinsic since Java 6u18) in a naive loop, see LUCENE-2221
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