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comparison graal/com.oracle.jvmci.common/src/com/oracle/jvmci/common/UnsafeAccess.java @ 21541:5e868236654f

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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
comparison
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21540:ccb1b1391192 21541:5e868236654f
1 /*
2 * Copyright (c) 2012, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package com.oracle.jvmci.common;
24
25 import java.lang.reflect.*;
26
27 import sun.misc.*;
28
29 public class UnsafeAccess {
30
31 /**
32 * An instance of {@link Unsafe} for use within Graal.
33 */
34 public static final Unsafe unsafe;
35
36 static {
37 try {
38 Field theUnsafeInstance = Unsafe.class.getDeclaredField("theUnsafe");
39 theUnsafeInstance.setAccessible(true);
40 unsafe = (Unsafe) theUnsafeInstance.get(Unsafe.class);
41 } catch (Exception e) {
42 throw new RuntimeException("exception while trying to get Unsafe", e);
43 }
44 }
45
46 /**
47 * Copies the contents of a {@link String} to a native memory buffer as a {@code '\0'}
48 * terminated C string. The native memory buffer is allocated via
49 * {@link Unsafe#allocateMemory(long)}. The caller is responsible for releasing the buffer when
50 * it is no longer needed via {@link Unsafe#freeMemory(long)}.
51 *
52 * @return the native memory pointer of the C string created from {@code s}
53 */
54 public static long createCString(String s) {
55 return writeCString(s, unsafe.allocateMemory(s.length() + 1));
56 }
57
58 /**
59 * Reads a {@code '\0'} terminated C string from native memory and converts it to a
60 * {@link String}.
61 *
62 * @return a Java string
63 */
64 public static String readCString(long address) {
65 if (address == 0) {
66 return null;
67 }
68 StringBuilder sb = new StringBuilder();
69 for (int i = 0;; i++) {
70 char c = (char) unsafe.getByte(address + i);
71 if (c == 0) {
72 break;
73 }
74 sb.append(c);
75 }
76 return sb.toString();
77 }
78
79 /**
80 * Writes the contents of a {@link String} to a native memory buffer as a {@code '\0'}
81 * terminated C string. The caller is responsible for ensuring the buffer is at least
82 * {@code s.length() + 1} bytes long. The caller is also responsible for releasing the buffer
83 * when it is no longer.
84 *
85 * @return the value of {@code buf}
86 */
87 public static long writeCString(String s, long buf) {
88 int size = s.length();
89 for (int i = 0; i < size; i++) {
90 unsafe.putByte(buf + i, (byte) s.charAt(i));
91 }
92 unsafe.putByte(buf + size, (byte) '\0');
93 return buf;
94 }
95 }