mirror of https://github.com/apache/lucene.git
LUCENE-2946: put vint table from fileformats in writeVInt
git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1330511 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Robert Muir
parent
d5e8cf0487
commit
d1562ef683
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@ -79,6 +79,9 @@ public abstract class DataInput implements Cloneable {
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/** Reads an int stored in variable-length format. Reads between one and
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* five bytes. Smaller values take fewer bytes. Negative numbers are not
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* supported.
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* <p>
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* The format is described further in {@link DataOutput#writeVInt(int)}.
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*
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* @see DataOutput#writeVInt(int)
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*/
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public int readVInt() throws IOException {
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@ -121,7 +124,12 @@ public abstract class DataInput implements Cloneable {
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/** Reads a long stored in variable-length format. Reads between one and
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* nine bytes. Smaller values take fewer bytes. Negative numbers are not
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* supported. */
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* supported.
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* <p>
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* The format is described further in {@link DataOutput#writeVInt(int)}.
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*
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* @see DataOutput#writeVLong(long)
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*/
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public long readVLong() throws IOException {
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/* This is the original code of this method,
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* but a Hotspot bug (see LUCENE-2975) corrupts the for-loop if
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@ -72,6 +72,107 @@ public abstract class DataOutput {
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/** Writes an int in a variable-length format. Writes between one and
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* five bytes. Smaller values take fewer bytes. Negative numbers are
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* supported, but should be avoided.
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* <p>VByte is a variable-length format for positive integers is defined where the
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* high-order bit of each byte indicates whether more bytes remain to be read. The
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* low-order seven bits are appended as increasingly more significant bits in the
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* resulting integer value. Thus values from zero to 127 may be stored in a single
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* byte, values from 128 to 16,383 may be stored in two bytes, and so on.</p>
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* <p>VByte Encoding Example</p>
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* <table cellspacing="0" cellpadding="2" border="0">
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* <col width="64*">
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* <col width="64*">
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* <col width="64*">
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* <col width="64*">
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* <tr valign="top">
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* <th align="left" width="25%">Value</th>
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* <th align="left" width="25%">Byte 1</th>
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* <th align="left" width="25%">Byte 2</th>
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* <th align="left" width="25%">Byte 3</th>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">0</td>
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* <td width="25%"><kbd>00000000</kbd></td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">1</td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">2</td>
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* <td width="25%"><kbd>00000010</kbd></td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* </tr>
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* <tr>
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* <td valign="top" width="25%">...</td>
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* <td valign="bottom" width="25%"></td>
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* <td valign="bottom" width="25%"></td>
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* <td valign="bottom" width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">127</td>
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* <td width="25%"><kbd>01111111</kbd></td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">128</td>
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* <td width="25%"><kbd>10000000</kbd></td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">129</td>
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* <td width="25%"><kbd>10000001</kbd></td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">130</td>
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* <td width="25%"><kbd>10000010</kbd></td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* <td width="25%"></td>
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* </tr>
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* <tr>
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* <td valign="top" width="25%">...</td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">16,383</td>
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* <td width="25%"><kbd>11111111</kbd></td>
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* <td width="25%"><kbd>01111111</kbd></td>
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* <td width="25%"></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">16,384</td>
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* <td width="25%"><kbd>10000000</kbd></td>
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* <td width="25%"><kbd>10000000</kbd></td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* </tr>
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* <tr valign="bottom">
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* <td width="25%">16,385</td>
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* <td width="25%"><kbd>10000001</kbd></td>
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* <td width="25%"><kbd>10000000</kbd></td>
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* <td width="25%"><kbd>00000001</kbd></td>
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* </tr>
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* <tr>
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* <td valign="top" width="25%">...</td>
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* <td valign="bottom" width="25%"></td>
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* <td valign="bottom" width="25%"></td>
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* <td valign="bottom" width="25%"></td>
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* </tr>
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* </table>
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* <p>This provides compression while still being efficient to decode.</p>
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*
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* @param i Smaller values take fewer bytes. Negative numbers are
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* supported, but should be avoided.
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* @throws IOException If there is an I/O error writing to the underlying medium.
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* @see DataInput#readVInt()
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*/
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public final void writeVInt(int i) throws IOException {
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@ -93,6 +194,8 @@ public abstract class DataOutput {
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/** Writes an long in a variable-length format. Writes between one and nine
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* bytes. Smaller values take fewer bytes. Negative numbers are not
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* supported.
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* <p>
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* The format is described further in {@link DataOutput#writeVInt(int)}.
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* @see DataInput#readVLong()
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*/
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public final void writeVLong(long i) throws IOException {
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