diff jvmci/jdk.vm.ci.common/src/jdk/vm/ci/common/UnsafeUtil.java @ 23392:b3a816d3b844

Backed out changeset: a920338dd4d4
author Doug Simon <doug.simon@oracle.com>
date Thu, 12 May 2016 11:06:49 +0200
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jvmci/jdk.vm.ci.common/src/jdk/vm/ci/common/UnsafeUtil.java	Thu May 12 11:06:49 2016 +0200
@@ -0,0 +1,81 @@
+/*
+ * 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 jdk.vm.ci.common;
+
+import sun.misc.Unsafe;
+
+/**
+ * Utilities for operating on raw memory with {@link Unsafe}.
+ */
+public class UnsafeUtil {
+
+    /**
+     * 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(Unsafe unsafe, String s) {
+        return writeCString(unsafe, 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(Unsafe unsafe, 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(Unsafe unsafe, 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;
+    }
+}