com.facebook.presto.jdbc.internal.spi.block.EncoderUtil Maven / Gradle / Ivy
/*
* 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.facebook.presto.jdbc.internal.spi.block;
import com.facebook.presto.jdbc.internal.airlift.slice.SliceInput;
import com.facebook.presto.jdbc.internal.airlift.slice.SliceOutput;
final class EncoderUtil
{
private EncoderUtil()
{
}
/**
* Append null values for the block as a stream of bits.
*/
public static void encodeNullsAsBits(SliceOutput sliceOutput, Block block)
{
int positionCount = block.getPositionCount();
for (int position = 0; position < (positionCount & ~0b111); position += 8) {
byte value = 0;
value |= block.isNull(position) ? 0b1000_0000 : 0;
value |= block.isNull(position + 1) ? 0b0100_0000 : 0;
value |= block.isNull(position + 2) ? 0b0010_0000 : 0;
value |= block.isNull(position + 3) ? 0b0001_0000 : 0;
value |= block.isNull(position + 4) ? 0b0000_1000 : 0;
value |= block.isNull(position + 5) ? 0b0000_0100 : 0;
value |= block.isNull(position + 6) ? 0b0000_0010 : 0;
value |= block.isNull(position + 7) ? 0b0000_0001 : 0;
sliceOutput.appendByte(value);
}
}
/**
* Decode the bit stream created by encodeNullsAsBits.
*/
public static boolean[] decodeNullBits(SliceInput sliceInput, int positionCount)
{
// read null bits 8 at a time
boolean[] valueIsNull = new boolean[positionCount];
for (int position = 0; position < (positionCount & ~0b111); position += 8) {
byte value = sliceInput.readByte();
valueIsNull[position] = ((value & 0b1000_0000) != 0);
valueIsNull[position + 1] = ((value & 0b0100_0000) != 0);
valueIsNull[position + 2] = ((value & 0b0010_0000) != 0);
valueIsNull[position + 3] = ((value & 0b0001_0000) != 0);
valueIsNull[position + 4] = ((value & 0b0000_1000) != 0);
valueIsNull[position + 5] = ((value & 0b0000_0100) != 0);
valueIsNull[position + 6] = ((value & 0b0000_0010) != 0);
valueIsNull[position + 7] = ((value & 0b0000_0001) != 0);
}
// read last null bits
if ((positionCount & 0b111) > 0) {
byte value = sliceInput.readByte();
int mask = 0b1000_0000;
for (int position = positionCount & ~0b111; position < positionCount; position++) {
valueIsNull[position] = ((value & mask) != 0);
mask >>>= 1;
}
}
return valueIsNull;
}
}