/*
* Copyright (c) 2008-2014 MongoDB, Inc.
*
* 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 org.bson.io;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
/**
* Utility class for reading values from an input stream.
*/
public class Bits {
/**
* Reads bytes from the input stream and puts them into the given byte buffer. The equivalent of calling
* {@link #readFully(java.io.InputStream, byte[], int, int)} with an offset of zero and a length equal to the length of the buffer.
*
* @param inputStream the input stream to read from
* @param buffer the buffer into which the data is read.
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static void readFully(final InputStream inputStream, final byte[] buffer)
throws IOException {
readFully(inputStream, buffer, buffer.length);
}
/**
* Reads bytes from the input stream and puts them into the given byte buffer. The equivalent of calling
* {@link #readFully(java.io.InputStream, byte[], int, int)} with an offset of zero.
*
* @param inputStream the input stream to read from
* @param buffer the buffer into which the data is read.
* @param length the maximum number of bytes to read.
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static void readFully(final InputStream inputStream, final byte[] buffer, final int length)
throws IOException {
readFully(inputStream, buffer, 0, length);
}
/**
* Reads bytes from the input stream and puts them into the given byte buffer.
*
* @param inputStream the input stream to read from
* @param buffer the buffer into which the data is read.
* @param offset the start offset in array {@code buffer} at which the data is written.
* @param length the maximum number of bytes to read.
* @throws IOException if there's an error reading from the {@code inputStream}
* @see java.io.InputStream#read(byte[], int, int)
*/
public static void readFully(final InputStream inputStream, final byte[] buffer, final int offset, final int length)
throws IOException {
if (buffer.length < length + offset) {
throw new IllegalArgumentException("Buffer is too small");
}
int arrayOffset = offset;
int bytesToRead = length;
while (bytesToRead > 0) {
int bytesRead = inputStream.read(buffer, arrayOffset, bytesToRead);
if (bytesRead < 0) {
throw new EOFException();
}
bytesToRead -= bytesRead;
arrayOffset += bytesRead;
}
}
/**
* Reads and returns a single integer value from the input stream.
*
* @param inputStream the input stream to read from
* @return the integer value
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static int readInt(final InputStream inputStream) throws IOException {
return readInt(inputStream, new byte[4]);
}
/**
* Reads and returns a single integer value from the input stream.
*
* @param inputStream the input stream to read from
* @param buffer the buffer to write the input stream bytes into
* @return the integer value
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static int readInt(final InputStream inputStream, final byte[] buffer) throws IOException {
readFully(inputStream, buffer, 4);
return readInt(buffer);
}
/**
* Reads and returns a single integer value from the buffer. The equivalent of calling {@link #readInt(byte[], int)}
* with an offset of zero.
*
* @param buffer the buffer to read from
* @return the integer value
*/
public static int readInt(final byte[] buffer) {
return readInt(buffer, 0);
}
/**
* Reads and returns a single integer value from the buffer.
*
* @param buffer the buffer to read from
* @param offset the position to start reading from the buffer
* @return the integer value
*/
public static int readInt(final byte[] buffer, final int offset) {
int x = 0;
x |= (0xFF & buffer[offset + 0]) << 0;
x |= (0xFF & buffer[offset + 1]) << 8;
x |= (0xFF & buffer[offset + 2]) << 16;
x |= (0xFF & buffer[offset + 3]) << 24;
return x;
}
/**
* Reads and returns a single big-endian integer value
*
* @param buffer the buffer to read from
* @param offset the position to start reading from the buffer
* @return the integer value
*/
public static int readIntBE(final byte[] buffer, final int offset) {
int x = 0;
x |= (0xFF & buffer[offset + 0]) << 24;
x |= (0xFF & buffer[offset + 1]) << 16;
x |= (0xFF & buffer[offset + 2]) << 8;
x |= (0xFF & buffer[offset + 3]) << 0;
return x;
}
/**
* Reads and returns a single long value from the input stream.
*
* @param inputStream the input stream to read from
* @return the long value
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static long readLong(final InputStream inputStream) throws IOException {
return readLong(inputStream, new byte[8]);
}
/**
* Reads and returns a single long value from the input stream.
*
* @param inputStream the input stream to read from
* @param buffer the buffer to write the input stream bytes into
* @return the long value
* @throws IOException if there's an error reading from the {@code inputStream}
*/
public static long readLong(final InputStream inputStream, final byte[] buffer) throws IOException {
readFully(inputStream, buffer, 8);
return readLong(buffer);
}
/**
* Reads and returns a single long value from the buffer. The equivalent of called {@link #readLong(byte[], int)} with an offset of
* zero.
*
* @param buffer the buffer to read from
* @return the long value
*/
public static long readLong(final byte[] buffer) {
return readLong(buffer, 0);
}
/**
* Reads and returns a single long value from the buffer.
*
* @param buffer the buffer to read from
* @param offset the position to start reading from the buffer
* @return the long value
*/
public static long readLong(final byte[] buffer, final int offset) {
long x = 0;
x |= (0xFFL & buffer[offset + 0]) << 0;
x |= (0xFFL & buffer[offset + 1]) << 8;
x |= (0xFFL & buffer[offset + 2]) << 16;
x |= (0xFFL & buffer[offset + 3]) << 24;
x |= (0xFFL & buffer[offset + 4]) << 32;
x |= (0xFFL & buffer[offset + 5]) << 40;
x |= (0xFFL & buffer[offset + 6]) << 48;
x |= (0xFFL & buffer[offset + 7]) << 56;
return x;
}
}