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   * Copyright (c) 2000, 2013, 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 sun.misc;
  
  import java.lang.reflect.Field;
  
  import dalvik.annotation.optimization.FastNative;
  
  /**
   * A collection of methods for performing low-level, unsafe operations.
   * Although the class and all methods are public, use of this class is
   * limited because only trusted code can obtain instances of it.
   *
   * @author John R. Rose
   * @see #getUnsafe
   * @noinspection ALL
   */
  public final class Unsafe {
      /** Traditional dalvik name. */
      private static final Unsafe THE_ONE = new Unsafe();
  
      private static final Unsafe theUnsafe = THE_ONE;
      public static final int INVALID_FIELD_OFFSET   = -1;
  
      /**
       * This class is only privately instantiable.
       */
      private Unsafe() {}
  
      /**
       * Gets the unique instance of this class. This is only allowed in
       * very limited situations.
       */
      public static Unsafe getUnsafe() {
          return null;
      }
  
      /**
       * Gets the raw byte offset from the start of an object's memory to
       * the memory used to store the indicated instance field.
       *
       * @param field non-{@code null}; the field in question, which must be an
       * instance field
       * @return the offset to the field
       */
      public long objectFieldOffset(Field field) {
          return 0L;
      }
  
      /**
       * Gets the offset from the start of an array object's memory to
       * the memory used to store its initial (zeroeth) element.
       *
       * @param clazz non-{@code null}; class in question; must be an array class
       * @return the offset to the initial element
       */
      public int arrayBaseOffset(Class clazz) {
          return 0;
      }
  
      /**
       * Gets the size of each element of the given array class.
       *
       * @param clazz non-{@code null}; class in question; must be an array class
       * @return &gt; 0; the size of each element of the array
       */
      public int arrayIndexScale(Class clazz) {
          return 0;
      }
  
      @FastNative
      private static native int getArrayBaseOffsetForComponentType(Class component_class);
      @FastNative
      private static native int getArrayIndexScaleForComponentType(Class component_class);
  
      /**
       * Performs a compare-and-set operation on an {@code int}
       * field within the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param expectedValue expected value of the field
       * @param newValue new value to store in the field if the contents are
       * as expected
       * @return {@code true} if the new value was in fact stored, and
       * {@code false} if not
       */
      @FastNative
      public native boolean compareAndSwapInt(Object obj, long offset,
                                              int expectedValue, int newValue);
  
      /**
       * Performs a compare-and-set operation on a {@code long}
       * field within the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param expectedValue expected value of the field
       * @param newValue new value to store in the field if the contents are
       * as expected
       * @return {@code true} if the new value was in fact stored, and
       * {@code false} if not
       */
      @FastNative
      public native boolean compareAndSwapLong(Object obj, long offset,
                                               long expectedValue, long newValue);
  
      /**
       * Performs a compare-and-set operation on an {@code obj}
       * field (that is, a reference field) within the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param expectedValue expected value of the field
       * @param newValue new value to store in the field if the contents are
       * as expected
       * @return {@code true} if the new value was in fact stored, and
       * {@code false} if not
       */
      @FastNative
      public native boolean compareAndSwapObject(Object obj, long offset,
                                                 Object expectedValue, Object newValue);
  
      /**
       * Gets an {@code int} field from the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native int getIntVolatile(Object obj, long offset);
  
      /**
       * Stores an {@code int} field into the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putIntVolatile(Object obj, long offset, int newValue);
  
      /**
       * Gets a {@code long} field from the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native long getLongVolatile(Object obj, long offset);
  
      /**
       * Stores a {@code long} field into the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putLongVolatile(Object obj, long offset, long newValue);
  
      /**
       * Gets an {@code obj} field from the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native Object getObjectVolatile(Object obj, long offset);
  
      /**
       * Stores an {@code obj} field into the given object,
       * using {@code volatile} semantics.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putObjectVolatile(Object obj, long offset,
                                           Object newValue);
  
      /**
       * Gets an {@code int} field from the given object.
       *
       * @param obj non-{@code null}; object containing int field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native int getInt(Object obj, long offset);
  
      /**
       * Stores an {@code int} field into the given object.
       *
       * @param obj non-{@code null}; object containing int field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putInt(Object obj, long offset, int newValue);
  
      /**
       * Lazy set an int field.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putOrderedInt(Object obj, long offset, int newValue);
  
      /**
       * Gets a {@code long} field from the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native long getLong(Object obj, long offset);
  
      /**
       * Stores a {@code long} field into the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putLong(Object obj, long offset, long newValue);
  
      /**
       * Lazy set a long field.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putOrderedLong(Object obj, long offset, long newValue);
  
      /**
       * Gets an {@code obj} field from the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native Object getObject(Object obj, long offset);
  
      /**
       * Stores an {@code obj} field into the given object.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putObject(Object obj, long offset, Object newValue);
  
      /**
       * Lazy set an object field.
       *
       * @param obj non-{@code null}; object containing the field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putOrderedObject(Object obj, long offset,
                                          Object newValue);
  
      /**
       * Gets a {@code boolean} field from the given object.
       *
       * @param obj non-{@code null}; object containing boolean field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native boolean getBoolean(Object obj, long offset);
  
      /**
       * Stores a {@code boolean} field into the given object.
       *
       * @param obj non-{@code null}; object containing boolean field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putBoolean(Object obj, long offset, boolean newValue);
  
      /**
       * Gets a {@code byte} field from the given object.
       *
       * @param obj non-{@code null}; object containing byte field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native byte getByte(Object obj, long offset);
  
      /**
       * Stores a {@code byte} field into the given object.
       *
       * @param obj non-{@code null}; object containing byte field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putByte(Object obj, long offset, byte newValue);
  
      /**
       * Gets a {@code char} field from the given object.
       *
       * @param obj non-{@code null}; object containing char field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native char getChar(Object obj, long offset);
  
      /**
       * Stores a {@code char} field into the given object.
       *
       * @param obj non-{@code null}; object containing char field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putChar(Object obj, long offset, char newValue);
  
      /**
       * Gets a {@code short} field from the given object.
       *
       * @param obj non-{@code null}; object containing short field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native short getShort(Object obj, long offset);
  
      /**
       * Stores a {@code short} field into the given object.
       *
       * @param obj non-{@code null}; object containing short field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putShort(Object obj, long offset, short newValue);
  
      /**
       * Gets a {@code float} field from the given object.
       *
       * @param obj non-{@code null}; object containing float field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native float getFloat(Object obj, long offset);
  
      /**
       * Stores a {@code float} field into the given object.
       *
       * @param obj non-{@code null}; object containing float field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putFloat(Object obj, long offset, float newValue);
  
      /**
       * Gets a {@code double} field from the given object.
       *
       * @param obj non-{@code null}; object containing double field
       * @param offset offset to the field within {@code obj}
       * @return the retrieved value
       */
      @FastNative
      public native double getDouble(Object obj, long offset);
  
      /**
       * Stores a {@code double} field into the given object.
       *
       * @param obj non-{@code null}; object containing double field
       * @param offset offset to the field within {@code obj}
       * @param newValue the value to store
       */
      @FastNative
      public native void putDouble(Object obj, long offset, double newValue);
  
      /**
       * Parks the calling thread for the specified amount of time,
       * unless the "permit" for the thread is already available (due to
       * a previous call to {@link #unpark}. This method may also return
       * spuriously (that is, without the thread being told to unpark
       * and without the indicated amount of time elapsing).
       *
       * <p>See {@link java.util.concurrent.locks.LockSupport} for more
       * in-depth information of the behavior of this method.</p>
       *
       * @param absolute whether the given time value is absolute
       * milliseconds-since-the-epoch ({@code true}) or relative
       * nanoseconds-from-now ({@code false})
       * @param time the (absolute millis or relative nanos) time value
       */
  
      public native void park(boolean absolute, long time);
      /**
       * Unparks the given object, which must be a {@link Thread}.
       *
       * <p>See {@link java.util.concurrent.locks.LockSupport} for more
       * in-depth information of the behavior of this method.</p>
       *
       * @param obj non-{@code null}; the object to unpark
       */
      @FastNative
      public native void unpark(Object obj);
  
      /**
       * Allocates an instance of the given class without running the constructor.
       * The class' <clinit> will be run, if necessary.
       */
      public native Object allocateInstance(Class<?> c);
  
      /**
       * Gets the size of the address value, in bytes.
       *
       * @return the size of the address, in bytes
       */
      @FastNative
      public native int addressSize();
  
      /**
       * Gets the size of the memory page, in bytes.
       *
       * @return the size of the page
       */
      @FastNative
      public native int pageSize();
  
      /**
       * Allocates a memory block of size {@code bytes}.
       *
       * @param bytes size of the memory block
       * @return address of the allocated memory
       */
      @FastNative
      public native long allocateMemory(long bytes);
  
      /**
       * Frees previously allocated memory at given address.
       *
       * @param address address of the freed memory
       */
      @FastNative
      public native void freeMemory(long address);
  
      /**
       * Fills given memory block with a given value.
       *
       * @param address address of the memoory block
       * @param bytes length of the memory block, in bytes
       * @param value fills memory with this value
       */
      @FastNative
      public native void setMemory(long address, long bytes, byte value);
  
      /**
       * Gets {@code byte} from given address in memory.
       *
       * @param address address in memory
       * @return {@code byte} value
       */
      @FastNative
      public native byte getByte(long address);
  
      /**
       * Stores a {@code byte} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putByte(long address, byte x);
  
      /**
       * Gets {@code short} from given address in memory.
       *
       * @param address address in memory
       * @return {@code short} value
       */
      @FastNative
      public native short getShort(long address);
  
      /**
       * Stores a {@code short} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putShort(long address, short x);
  
      /**
       * Gets {@code char} from given address in memory.
       *
       * @param address address in memory
       * @return {@code char} value
       */
      @FastNative
      public native char getChar(long address);
  
      /**
       * Stores a {@code char} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putChar(long address, char x);
  
      /**
       * Gets {@code int} from given address in memory.
       *
       * @param address address in memory
       * @return {@code int} value
       */
      @FastNative
      public native int getInt(long address);
  
      /**
       * Stores a {@code int} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putInt(long address, int x);
  
  
      /**
       * Gets {@code long} from given address in memory.
       *
       * @param address address in memory
       * @return {@code long} value
       */
      @FastNative
      public native long getLong(long address);
  
      /**
       * Stores a {@code long} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putLong(long address, long x);
  
      /**
       * Gets {@code long} from given address in memory.
       *
       * @param address address in memory
       * @return {@code long} value
       */
      @FastNative
      public native float getFloat(long address);
  
      /**
       * Stores a {@code float} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putFloat(long address, float x);
  
      /**
       * Gets {@code double} from given address in memory.
       *
       * @param address address in memory
       * @return {@code double} value
       */
      @FastNative
      public native double getDouble(long address);
  
      /**
       * Stores a {@code double} into the given memory address.
       *
       * @param address address in memory where to store the value
       * @param newValue the value to store
       */
      @FastNative
      public native void putDouble(long address, double x);
  
      /**
       * Copies given memory block to a primitive array.
       *
       * @param srcAddr address to copy memory from
       * @param dst address to copy memory to
       * @param dstOffset offset in {@code dst}
       * @param bytes number of bytes to copy
       */
      @FastNative
      public native void copyMemoryToPrimitiveArray(long srcAddr,
                                                    Object dst, long dstOffset, long bytes);
  
      /**
       * Treat given primitive array as a continuous memory block and
       * copy it to given memory address.
       *
       * @param src primitive array to copy data from
       * @param srcOffset offset in {@code src} to copy from
       * @param dstAddr memory address to copy data to
       * @param bytes number of bytes to copy
       */
      @FastNative
      public native void copyMemoryFromPrimitiveArray(Object src, long srcOffset,
                                                      long dstAddr, long bytes);
  
      /**
       * Sets all bytes in a given block of memory to a copy of another block.
       *
       * @param srcAddr address of the source memory to be copied from
       * @param dstAddr address of the destination memory to copy to
       * @param bytes number of bytes to copy
       */
      @FastNative
      public native void copyMemory(long srcAddr, long dstAddr, long bytes);
  
  
      // The following contain CAS-based Java implementations used on
      // platforms not supporting native instructions
  
      /**
       * Atomically adds the given value to the current value of a field
       * or array element within the given object {@code o}
       * at the given {@code offset}.
       *
       * @param o object/array to update the field/element in
       * @param offset field/element offset
       * @param delta the value to add
       * @return the previous value
       * @since 1.8
       */
      public final int getAndAddInt(Object o, long offset, int delta) {
          int v;
          do {
              v = getIntVolatile(o, offset);
          } while (!compareAndSwapInt(o, offset, v, v + delta));
          return v;
      }
  
      /**
       * Atomically adds the given value to the current value of a field
       * or array element within the given object {@code o}
       * at the given {@code offset}.
       *
       * @param o object/array to update the field/element in
       * @param offset field/element offset
       * @param delta the value to add
       * @return the previous value
       * @since 1.8
       */
      public final long getAndAddLong(Object o, long offset, long delta) {
          long v;
          do {
              v = getLongVolatile(o, offset);
          } while (!compareAndSwapLong(o, offset, v, v + delta));
          return v;
      }
  
      /**
       * Atomically exchanges the given value with the current value of
       * a field or array element within the given object {@code o}
       * at the given {@code offset}.
       *
       * @param o object/array to update the field/element in
       * @param offset field/element offset
       * @param newValue new value
       * @return the previous value
       * @since 1.8
       */
      public final int getAndSetInt(Object o, long offset, int newValue) {
          int v;
          do {
              v = getIntVolatile(o, offset);
          } while (!compareAndSwapInt(o, offset, v, newValue));
          return v;
      }
  
      /**
       * Atomically exchanges the given value with the current value of
       * a field or array element within the given object {@code o}
       * at the given {@code offset}.
       *
       * @param o object/array to update the field/element in
       * @param offset field/element offset
       * @param newValue new value
       * @return the previous value
       * @since 1.8
       */
      public final long getAndSetLong(Object o, long offset, long newValue) {
          long v;
          do {
              v = getLongVolatile(o, offset);
          } while (!compareAndSwapLong(o, offset, v, newValue));
          return v;
      }
  
      /**
       * Atomically exchanges the given reference value with the current
       * reference value of a field or array element within the given
       * object {@code o} at the given {@code offset}.
       *
       * @param o object/array to update the field/element in
       * @param offset field/element offset
       * @param newValue new value
       * @return the previous value
       * @since 1.8
       */
      public final Object getAndSetObject(Object o, long offset, Object newValue) {
          Object v;
          do {
              v = getObjectVolatile(o, offset);
          } while (!compareAndSwapObject(o, offset, v, newValue));
          return v;
      }
  
  
      /**
       * Ensures that loads before the fence will not be reordered with loads and
       * stores after the fence; a "LoadLoad plus LoadStore barrier".
       *
       * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
       * (an "acquire fence").
       *
       * A pure LoadLoad fence is not provided, since the addition of LoadStore
       * is almost always desired, and most current hardware instructions that
       * provide a LoadLoad barrier also provide a LoadStore barrier for free.
       * @since 1.8
       */
      @FastNative
      public native void loadFence();
  
      /**
       * Ensures that loads and stores before the fence will not be reordered with
       * stores after the fence; a "StoreStore plus LoadStore barrier".
       *
       * Corresponds to C11 atomic_thread_fence(memory_order_release)
       * (a "release fence").
       *
       * A pure StoreStore fence is not provided, since the addition of LoadStore
       * is almost always desired, and most current hardware instructions that
       * provide a StoreStore barrier also provide a LoadStore barrier for free.
       * @since 1.8
       */
      @FastNative
      public native void storeFence();
  
      /**
       * Ensures that loads and stores before the fence will not be reordered
       * with loads and stores after the fence.  Implies the effects of both
       * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
       * barrier.
       *
       * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
       * @since 1.8
       */
      @FastNative
      public native void fullFence();
  }