/*

 * Copyright (c) 2000, 2002, 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.nio.ch;                                     // Formerly in sun.misc

import java.nio.ByteOrder;

import jdk.internal.misc.Unsafe;

// ## In the fullness of time, this class will be eliminated

/**

 * Proxies for objects that reside in native memory.

 */

class NativeObject {                                    // package-private

    protected static final Unsafe unsafe = Unsafe.getUnsafe();

    // Native allocation address;

    // may be smaller than the base address due to page-size rounding

    //

    protected long allocationAddress;

    // Native base address

    //

    private final long address;

    /**

     * Creates a new native object that is based at the given native address.

     */

    NativeObject(long address) {

        this.allocationAddress = address;

        this.address = address;

    }

    /**

     * Creates a new native object allocated at the given native address but

     * whose base is at the additional offset.

     */

    NativeObject(long address, long offset) {

        this.allocationAddress = address;

        this.address = address + offset;

    }

    // Invoked only by AllocatedNativeObject

    //

    protected NativeObject(int size, boolean pageAligned) {

        if (!pageAligned) {

            this.allocationAddress = unsafe.allocateMemory(size);

            this.address = this.allocationAddress;

        } else {

            int ps = pageSize();

            long a = unsafe.allocateMemory(size + ps);

            this.allocationAddress = a;

            this.address = a + ps - (a & (ps - 1));

        }

    }

    /**

     * Returns the native base address of this native object.

     *

     * @return The native base address

     */

    long address() {

        return address;

    }

    long allocationAddress() {

        return allocationAddress;

    }

    /**

     * Creates a new native object starting at the given offset from the base

     * of this native object.

     *

     * @param  offset

     *         The offset from the base of this native object that is to be

     *         the base of the new native object

     *

     * @return The newly created native object

     */

    NativeObject subObject(int offset) {

        return new NativeObject(offset + address);

    }

    /**

     * Reads an address from this native object at the given offset and

     * constructs a native object using that address.

     *

     * @param  offset

     *         The offset of the address to be read.  Note that the size of an

     *         address is implementation-dependent.

     *

     * @return The native object created using the address read from the

     *         given offset

     */

    NativeObject getObject(int offset) {

        long newAddress = 0L;

        switch (addressSize()) {

            case 8:

                newAddress = unsafe.getLong(offset + address);

                break;

            case 4:

                newAddress = unsafe.getInt(offset + address) & 0x00000000FFFFFFFF;

                break;

            default:

                throw new InternalError("Address size not supported");

        }

        return new NativeObject(newAddress);

    }

    /**

     * Writes the base address of the given native object at the given offset

     * of this native object.

     *

     * @param  offset

     *         The offset at which the address is to be written.  Note that the

     *         size of an address is implementation-dependent.

     *

     * @param  ob

     *         The native object whose address is to be written

     */

    void putObject(int offset, NativeObject ob) {

        switch (addressSize()) {

            case 8:

                putLong(offset, ob.address);

                break;

            case 4:

                putInt(offset, (int)(ob.address & 0x00000000FFFFFFFF));

                break;

            default:

                throw new InternalError("Address size not supported");

        }

    }

    /* -- Value accessors: No range checking! -- */

    /**

     * Reads a byte starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the byte

     *

     * @return The byte value read

     */

    final byte getByte(int offset) {

        return unsafe.getByte(offset + address);

    }

    /**

     * Writes a byte at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the byte

     *

     * @param  value

     *         The byte value to be written

     */

    final void putByte(int offset, byte value) {

        unsafe.putByte(offset + address,  value);

    }

    /**

     * Reads a short starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the short

     *

     * @return The short value read

     */

    final short getShort(int offset) {

        return unsafe.getShort(offset + address);

    }

    /**

     * Writes a short at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the short

     *

     * @param  value

     *         The short value to be written

     */

    final void putShort(int offset, short value) {

        unsafe.putShort(offset + address,  value);

    }

    /**

     * Reads a char starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the char

     *

     * @return The char value read

     */

    final char getChar(int offset) {

        return unsafe.getChar(offset + address);

    }

    /**

     * Writes a char at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the char

     *

     * @param  value

     *         The char value to be written

     */

    final void putChar(int offset, char value) {

        unsafe.putChar(offset + address,  value);

    }

    /**

     * Reads an int starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the int

     *

     * @return The int value read

     */

    final int getInt(int offset) {

        return unsafe.getInt(offset + address);

    }

    /**

     * Writes an int at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the int

     *

     * @param  value

     *         The int value to be written

     */

    final void putInt(int offset, int value) {

        unsafe.putInt(offset + address, value);

    }

    /**

     * Reads a long starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the long

     *

     * @return The long value read

     */

    final long getLong(int offset) {

        return unsafe.getLong(offset + address);

    }

    /**

     * Writes a long at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the long

     *

     * @param  value

     *         The long value to be written

     */

    final void putLong(int offset, long value) {

        unsafe.putLong(offset + address, value);

    }

    /**

     * Reads a float starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the float

     *

     * @return The float value read

     */

    final float getFloat(int offset) {

        return unsafe.getFloat(offset + address);

    }

    /**

     * Writes a float at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the float

     *

     * @param  value

     *         The float value to be written

     */

    final void putFloat(int offset, float value) {

        unsafe.putFloat(offset + address, value);

    }

    /**

     * Reads a double starting at the given offset from base of this native

     * object.

     *

     * @param  offset

     *         The offset at which to read the double

     *

     * @return The double value read

     */

    final double getDouble(int offset) {

        return unsafe.getDouble(offset + address);

    }

    /**

     * Writes a double at the specified offset from this native object's

     * base address.

     *

     * @param  offset

     *         The offset at which to write the double

     *

     * @param  value

     *         The double value to be written

     */

    final void putDouble(int offset, double value) {

        unsafe.putDouble(offset + address, value);

    }

    /**

     * Returns the native architecture's address size in bytes.

     *

     * @return The address size of the native architecture

     */

    static int addressSize() {

        return unsafe.addressSize();

    }

    // Cache for byte order

    private static ByteOrder byteOrder = null;

    /**

     * Returns the byte order of the underlying hardware.

     *

     * @return  An instance of {@link java.nio.ByteOrder}

     */

    static ByteOrder byteOrder() {

        if (byteOrder != null)

            return byteOrder;

        long a = unsafe.allocateMemory(8);

        try {

            unsafe.putLong(a, 0x0102030405060708L);

            byte b = unsafe.getByte(a);

            switch (b) {

            case 0x01: byteOrder = ByteOrder.BIG_ENDIAN;     break;

            case 0x08: byteOrder = ByteOrder.LITTLE_ENDIAN;  break;

            default:

                assert false;

            }

        } finally {

            unsafe.freeMemory(a);

        }

        return byteOrder;

    }

    /**

     * Cache for page size.

     * Lazily initialized via a data race; safe because ints are atomic.

     */

    private static int pageSize = -1;

    /**

     * Returns the page size of the underlying hardware.

     *

     * @return  The page size, in bytes

     */

    static int pageSize() {

        int value = pageSize;

        if (value == -1)

            pageSize = value = unsafe.pageSize();

        return value;

    }

}