com.marklogic.io.Decoder Maven / Gradle / Ivy
/*
* Copyright 2003-2019 MarkLogic Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.marklogic.io;
import java.io.DataInput;
import java.io.EOFException;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Decoder used to decode compressed tree data.
*
* @author jchen
*/
public class Decoder {
public static final Log LOG = LogFactory.getLog(Decoder.class);
DataInput in;
int numBitsInReg = 0;
public long reg = 0;
public Decoder(DataInput in) {
this.in = in;
}
private void load() throws IOException {
try {
long bits = in.readInt() & 0xffffffffL;
reg |= bits << numBitsInReg;
numBitsInReg += 32;
} catch (EOFException e) {
return;
}
}
private boolean load32(int[] array, int index) {
try {
array[index] = in.readInt();
return true;
} catch (EOFException e) {
return false;
} catch (IOException e) {
return false;
}
}
public long decodeUnsignedLong() throws IOException {
long lobits = decodeUnsigned() & 0xffffffffL;
long hibits = decodeUnsigned() & 0xffffffffL;
return (hibits<<32)|lobits;
}
public long decode64bits() throws IOException {
long lobits = decode32bits() & 0xffffffffL;
long hibits = decode32bits() & 0xffffffffL;
return (hibits << 32) | lobits;
}
public int decode32bits() throws IOException {
if (numBitsInReg == 0)
return in.readInt();
if (32 > numBitsInReg)
load();
int val = (int)(reg & 0xffffffffL);
reg >>>= 32;
numBitsInReg -= 32;
return val;
}
public double decodeDouble() throws IOException {
long lobits = decode32bits() & 0xffffffffL;
long hibits = decode32bits() & 0xffffffffL;
long bits = (hibits << 32) | lobits;
return Double.longBitsToDouble(bits);
}
public void realign()
{
if (numBitsInReg < 32) {
reg = 0;
numBitsInReg = 0;
} else {
reg >>= (numBitsInReg - 32);
numBitsInReg = 32;
}
}
public void decode(int[] array, int count) throws IOException {
if (count <= 4) {
for (int i = 0; i < count; i++) {
array[i] = decode32bits();
}
} else {
int i = 0;
realign();
if (numBitsInReg==32) {
++i;
array[0] = (int)reg;
reg = 0;
numBitsInReg = 0;
}
for ( ; i>>= n;
numBitsInReg -= n;
return v;
}
int _decodeUnary() throws IOException {
for (int i = 1;; ++i) {
if (i > numBitsInReg)
load();
long msk = (1L << i) - 1;
if ((reg & msk) == (msk >>> 1)) {
reg >>>= i;
numBitsInReg -= i;
return i - 1;
}
}
}
public int decodeUnsigned() throws IOException {
if (numBitsInReg < 16)
load();
int e, n, v;
if ((n = (e = unsigned1[(int)(reg & 0x3fL)]) >>> 5) <= 6)
v = e & 0x1f;
else if ((n = (e = unsigned2[(int)(reg & 0x7ffL)]) >>> 12) <= 11)
v = e & 0xfff;
else if ((n = (e = unsigned3[(int)(reg & 0xffffL)]) >>> 16) <= 16)
v = e & 0xffff;
else
return _decodeUnsigned();
reg >>>= n;
numBitsInReg -= n;
return v;
}
int _decodeUnsigned() throws IOException {
int nbits = decodeUnary() * 4;
if (nbits > numBitsInReg)
load();
long val = reg & ((nbits < 64) ? ((1L << nbits) - 1) : -1L);
for (int i = 0; i < nbits; i += 4)
val += (1L << i);
reg >>>= nbits;
numBitsInReg -= nbits;
return (int)(val & 0xffffffffL);
}
public int decodeUnsigned(int n) throws IOException {
if (n > numBitsInReg)
load();
long v = reg & ((n < 64) ? ((1L << n) - 1) : -1L);
reg >>>= n;
numBitsInReg -= n;
return (int)(v & 0xffffffffL);
}
private static final byte[] unary1Make() {
byte table[] = new byte[256];
for (int i = 0; i < 256; i++) {
table[i] = (byte)0xff;
for (int j = 0; j < 8; j++) {
if ((i & ((1 << (j + 1)) - 1)) != ((1 << j) - 1))
continue;
table[i] = (byte)j;
break;
}
}
if (LOG.isTraceEnabled()) {
LOG.trace("unary1 ");
for (int i=0; i<256; i++) {
LOG.trace(String.format("%02x \n", table[i]));
}
}
return table;
}
static final byte unary1[] = unary1Make();
private static final byte[] unary2Make() {
byte table[] = new byte[65536];
for (int i = 0; i < 65536; i++) {
table[i] = (byte)0xff;
for (int j = 0; j < 16; j++) {
if ((i & ((1 << (j + 1)) - 1)) != ((1 << j) - 1))
continue;
table[i] = (byte)j;
break;
}
}
return table;
}
static final byte unary2[] = unary2Make();
private static final byte[] unsigned1Make() {
byte table[] = new byte[64];
for (int i = 0; i < 64; i++) {
int entry = unary1[i];
int bbits = entry * 4;
int ubits = entry + 1;
if (bbits + ubits > 6)
table[i] = (byte)0xe0;
else {
int val = (i >>> ubits) & ((1 << bbits) - 1);
for (int j = 0; j < bbits; j += 4)
val += (1 << j);
table[i] = (byte)(((bbits + ubits) << 5) | val);
}
}
if (LOG.isTraceEnabled()) {
LOG.trace("unsigned1 ");
for (int i=0; i<64; i++) {
LOG.trace(String.format("%02x \n", table[i]));
}
}
return table;
}
static final byte unsigned1[] = unsigned1Make();
private static final short[] unsigned2Make() {
short table[] = new short[2048];
for (int i = 0; i < 2048; i++) {
int entry = unary2[i];
int bbits = entry * 4;
int ubits = entry + 1;
if (bbits + ubits > 11)
table[i] = (short)0xf000;
else {
int val = (i >>> ubits) & ((1 << bbits) - 1);
for (int j = 0; j < bbits; j += 4)
val += (1 << j);
table[i] = (short)(((bbits + ubits) << 12) | val);
}
}
if (LOG.isTraceEnabled()) {
LOG.trace("unsigned2 ");
for (int i=0; i<64; i++) {
LOG.trace(String.format("%04x \n", table[i]));
}
}
return table;
}
static final short unsigned2[] = unsigned2Make();
private static final int[] unsigned3Make() {
int table[] = new int[65536];
for (int i = 0; i < 65536; i++) {
int entry = unary2[i]&0xff;
int bbits = entry * 4;
int ubits = entry + 1;
if (bbits + ubits > 16)
table[i] = 0xffff0000;
else {
int val = (i >>> ubits) & ((1 << bbits) - 1);
for (int j = 0; j < bbits; j += 4)
val += (1 << j);
table[i] = (((bbits + ubits) << 16) | val);
}
}
if (LOG.isTraceEnabled()) {
LOG.trace("unsigned3 ");
for (int i=0; i<64; i++) {
LOG.trace(String.format("%08x \n", table[i]));
}
}
return table;
}
static final int unsigned3[] = unsigned3Make();
}