org.apache.hadoop.hive.ql.io.orc.BitFieldReader Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hive.ql.io.orc;
import java.io.EOFException;
import java.io.IOException;
import org.apache.hadoop.hive.ql.exec.vector.LongColumnVector;
class BitFieldReader {
private final RunLengthByteReader input;
private final int bitSize;
private int current;
private int bitsLeft;
private final int mask;
BitFieldReader(InStream input,
int bitSize) throws IOException {
this.input = new RunLengthByteReader(input);
this.bitSize = bitSize;
mask = (1 << bitSize) - 1;
}
private void readByte() throws IOException {
if (input.hasNext()) {
current = 0xff & input.next();
bitsLeft = 8;
} else {
throw new EOFException("Read past end of bit field from " + this);
}
}
int next() throws IOException {
int result = 0;
int bitsLeftToRead = bitSize;
while (bitsLeftToRead > bitsLeft) {
result <<= bitsLeft;
result |= current & ((1 << bitsLeft) - 1);
bitsLeftToRead -= bitsLeft;
readByte();
}
if (bitsLeftToRead > 0) {
result <<= bitsLeftToRead;
bitsLeft -= bitsLeftToRead;
result |= (current >>> bitsLeft) & ((1 << bitsLeftToRead) - 1);
}
return result & mask;
}
void nextVector(LongColumnVector previous, long previousLen)
throws IOException {
previous.isRepeating = true;
for (int i = 0; i < previousLen; i++) {
if (!previous.isNull[i]) {
previous.vector[i] = next();
} else {
// The default value of null for int types in vectorized
// processing is 1, so set that if the value is null
previous.vector[i] = 1;
}
// The default value for nulls in Vectorization for int types is 1
// and given that non null value can also be 1, we need to check for isNull also
// when determining the isRepeating flag.
if (previous.isRepeating
&& i > 0
&& ((previous.vector[i - 1] != previous.vector[i]) || (previous.isNull[i - 1] != previous.isNull[i]))) {
previous.isRepeating = false;
}
}
}
void seek(PositionProvider index) throws IOException {
input.seek(index);
int consumed = (int) index.getNext();
if (consumed > 8) {
throw new IllegalArgumentException("Seek past end of byte at " +
consumed + " in " + input);
} else if (consumed != 0) {
readByte();
bitsLeft = 8 - consumed;
} else {
bitsLeft = 0;
}
}
void skip(long items) throws IOException {
long totalBits = bitSize * items;
if (bitsLeft >= totalBits) {
bitsLeft -= totalBits;
} else {
totalBits -= bitsLeft;
input.skip(totalBits / 8);
current = input.next();
bitsLeft = (int) (8 - (totalBits % 8));
}
}
@Override
public String toString() {
return "bit reader current: " + current + " bits left: " + bitsLeft +
" bit size: " + bitSize + " from " + input;
}
}