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
line wrap: on
line diff
--- /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;
+    }
+}