Mercurial > hg > truffle
diff graal/com.oracle.jvmci.common/src/com/oracle/jvmci/common/UnsafeAccess.java @ 21541:5e868236654f
moved UnsafeAccess to com.oracle.jvmci.common (JBS:GRAAL-53)
author | Doug Simon <doug.simon@oracle.com> |
---|---|
date | Mon, 25 May 2015 22:17:10 +0200 |
parents | graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/UnsafeAccess.java@f137f1974f60 |
children | 5b9adb645217 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/com.oracle.jvmci.common/src/com/oracle/jvmci/common/UnsafeAccess.java Mon May 25 22:17:10 2015 +0200 @@ -0,0 +1,95 @@ +/* + * Copyright (c) 2012, 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. + * + * 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.jvmci.common; + +import java.lang.reflect.*; + +import sun.misc.*; + +public class UnsafeAccess { + + /** + * An instance of {@link Unsafe} for use within Graal. + */ + public static final Unsafe unsafe; + + static { + try { + Field theUnsafeInstance = Unsafe.class.getDeclaredField("theUnsafe"); + theUnsafeInstance.setAccessible(true); + unsafe = (Unsafe) theUnsafeInstance.get(Unsafe.class); + } catch (Exception e) { + throw new RuntimeException("exception while trying to get Unsafe", e); + } + } + + /** + * Copies the contents of a {@link String} to a native memory buffer as a {@code '\0'} + * terminated C string. The native memory buffer is allocated via + * {@link Unsafe#allocateMemory(long)}. The caller is responsible for releasing the buffer when + * it is no longer needed via {@link Unsafe#freeMemory(long)}. + * + * @return the native memory pointer of the C string created from {@code s} + */ + public static long createCString(String s) { + return writeCString(s, unsafe.allocateMemory(s.length() + 1)); + } + + /** + * Reads a {@code '\0'} terminated C string from native memory and converts it to a + * {@link String}. + * + * @return a Java string + */ + public static String readCString(long address) { + if (address == 0) { + return null; + } + StringBuilder sb = new StringBuilder(); + for (int i = 0;; i++) { + char c = (char) unsafe.getByte(address + i); + if (c == 0) { + break; + } + sb.append(c); + } + return sb.toString(); + } + + /** + * Writes the contents of a {@link String} to a native memory buffer as a {@code '\0'} + * terminated C string. The caller is responsible for ensuring the buffer is at least + * {@code s.length() + 1} bytes long. The caller is also responsible for releasing the buffer + * when it is no longer. + * + * @return the value of {@code buf} + */ + public static long writeCString(String s, long buf) { + int size = s.length(); + for (int i = 0; i < size; i++) { + unsafe.putByte(buf + i, (byte) s.charAt(i)); + } + unsafe.putByte(buf + size, (byte) '\0'); + return buf; + } +}