Mercurial > hg > graal-compiler
diff graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/serial/VariableLengthIntBuffer.java @ 12388:96c1d057a5ed
Truffle: Added experimental serialization API.
author | Christian Humer <christian.humer@gmail.com> |
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date | Wed, 02 Oct 2013 15:33:08 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/serial/VariableLengthIntBuffer.java Wed Oct 02 15:33:08 2013 +0200 @@ -0,0 +1,109 @@ +/* + * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +package com.oracle.truffle.api.nodes.serial; + +import java.nio.*; + +/** + * Experimental API. May change without notice. Simple variable length unsigned int buffer backed by + * a byte buffer. + */ +public class VariableLengthIntBuffer { + + public static final int NULL = -1; + + private ByteBuffer buffer; + + public VariableLengthIntBuffer(ByteBuffer buffer) { + this.buffer = buffer; + } + + public VariableLengthIntBuffer(byte[] array) { + buffer = ByteBuffer.wrap(array); + } + + /** + * Returns the backing byte buffer. + */ + public ByteBuffer getBuffer() { + return buffer; + } + + public byte[] getBytes() { + int pos = buffer.position(); + byte[] bytes = new byte[buffer.position()]; + buffer.rewind(); + buffer.get(bytes); + buffer.position(pos); + return bytes; + } + + public int get() { + byte peekByte = buffer.get(buffer.position()); + if ((peekByte & 0x80) == 0) { + // single byte encoding with prefix 0 (range 127) + return buffer.get(); // no bit to be masked + } else { + if (peekByte == (byte) 0xFF) { + buffer.get(); // skip one byte + return NULL; + } + int result = buffer.getInt() & 0x7FFF_FFFF; // first bit masked out + assert (result & 0x4000_0000) == 0; + return result; + } + } + + public void put(int i) { + ensureCapacity(); + if (i == NULL) { + buffer.put((byte) 0xFF); + } else if ((i & 0xFFFF_FF80) == 0) { // 7 bits data + buffer.put((byte) i); + } else if ((i & 0xC000_0000) == 0) { // 32 bits data + buffer.putInt(i | 0x8000_0000); // append leading 1 + } else { + throw new IllegalArgumentException("Integer out of encodeable " + i); + } + } + + private void ensureCapacity() { + if (buffer.position() + 4 > buffer.capacity()) { + ByteBuffer newBuffer = ByteBuffer.allocate(buffer.capacity() * 2); + + int pos = buffer.position(); + buffer.rewind(); + newBuffer.put(buffer); + newBuffer.position(pos); + + buffer = newBuffer; + } + } + + public boolean hasRemaining() { + return buffer.hasRemaining(); + } + +}