/*

 * Copyright 2005-2007 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.java2d.pipe;

import sun.misc.Unsafe;

/**

 * The RenderBuffer class is a simplified, high-performance, Unsafe wrapper

 * used for buffering rendering operations in a single-threaded rendering

 * environment.  It's functionality is similar to the ByteBuffer and related

 * NIO classes.  However, the methods in this class perform little to no

 * alignment or bounds checks for performance reasons.  Therefore, it is

 * the caller's responsibility to ensure that all put() calls are properly

 * aligned and within bounds:

 *   - int and float values must be aligned on 4-byte boundaries

 *   - long and double values must be aligned on 8-byte boundaries

 *

 * This class only includes the bare minimum of methods to support

 * single-threaded rendering.  For example, there is no put(double[]) method

 * because we currently have no need for such a method in the STR classes.

 */

public class RenderBuffer {

    /**

     * These constants represent the size of various data types (in bytes).

     */

    protected static final long SIZEOF_BYTE   = 1L;

    protected static final long SIZEOF_SHORT  = 2L;

    protected static final long SIZEOF_INT    = 4L;

    protected static final long SIZEOF_FLOAT  = 4L;

    protected static final long SIZEOF_LONG   = 8L;

    protected static final long SIZEOF_DOUBLE = 8L;

    /**

     * Represents the number of elements at which we have empirically

     * determined that the average cost of a JNI call exceeds the expense

     * of an element by element copy.  In other words, if the number of

     * elements in an array to be copied exceeds this value, then we should

     * use the copyFromArray() method to complete the bulk put operation.

     * (This value can be adjusted if the cost of JNI downcalls is reduced

     * in a future release.)

     */

    private static final int COPY_FROM_ARRAY_THRESHOLD = 28;

    protected final Unsafe unsafe;

    protected final long baseAddress;

    protected final long endAddress;

    protected long curAddress;

    protected final int capacity;

    protected RenderBuffer(int numBytes) {

        unsafe = Unsafe.getUnsafe();

        curAddress = baseAddress = unsafe.allocateMemory(numBytes);

        endAddress = baseAddress + numBytes;

        capacity = numBytes;

    }

    /**

     * Allocates a fresh buffer using the machine endianness.

     */

    public static RenderBuffer allocate(int numBytes) {

        return new RenderBuffer(numBytes);

    }

    /**

     * Returns the base address of the underlying memory buffer.

     */

    public final long getAddress() {

        return baseAddress;

    }

    /**

     * Copies length bytes from the Java-level srcArray to the native

     * memory located at dstAddr.  Note that this method performs no bounds

     * checking.  Verification that the copy will not result in memory

     * corruption should be done by the caller prior to invocation.

     *

     * @param srcArray the source array

     * @param srcPos the starting position of the source array (in bytes)

     * @param dstAddr pointer to the destination block of native memory

     * @param length the number of bytes to copy from source to destination

     */

    private static native void copyFromArray(Object srcArray, long srcPos,

                                             long dstAddr, long length);

    /**

     * The behavior (and names) of the following methods are nearly

     * identical to their counterparts in the various NIO Buffer classes.

     */

    public final int capacity() {

        return capacity;

    }

    public final int remaining() {

        return (int)(endAddress - curAddress);

    }

    public final int position() {

        return (int)(curAddress - baseAddress);

    }

    public final void position(long numBytes) {

        curAddress = baseAddress + numBytes;

    }

    public final void clear() {

        curAddress = baseAddress;

    }

    /**

     * putByte() methods...

     */

    public final RenderBuffer putByte(byte x) {

        unsafe.putByte(curAddress, x);

        curAddress += SIZEOF_BYTE;

        return this;

    }

    public RenderBuffer put(byte[] x) {

        return put(x, 0, x.length);

    }

    public RenderBuffer put(byte[] x, int offset, int length) {

        if (length > COPY_FROM_ARRAY_THRESHOLD) {

            long offsetInBytes = offset * SIZEOF_BYTE;

            long lengthInBytes = length * SIZEOF_BYTE;

            copyFromArray(x, offsetInBytes, curAddress, lengthInBytes);

            position(position() + lengthInBytes);

        } else {

            int end = offset + length;

            for (int i = offset; i < end; i++) {

                putByte(x[i]);

            }

        }

        return this;

    }

    /**

     * putShort() methods...

     */

    public final RenderBuffer putShort(short x) {

        // assert (position() % SIZEOF_SHORT == 0);

        unsafe.putShort(curAddress, x);

        curAddress += SIZEOF_SHORT;

        return this;

    }

    public RenderBuffer put(short[] x) {

        return put(x, 0, x.length);

    }

    public RenderBuffer put(short[] x, int offset, int length) {

        // assert (position() % SIZEOF_SHORT == 0);

        if (length > COPY_FROM_ARRAY_THRESHOLD) {

            long offsetInBytes = offset * SIZEOF_SHORT;

            long lengthInBytes = length * SIZEOF_SHORT;

            copyFromArray(x, offsetInBytes, curAddress, lengthInBytes);

            position(position() + lengthInBytes);

        } else {

            int end = offset + length;

            for (int i = offset; i < end; i++) {

                putShort(x[i]);

            }

        }

        return this;

    }

    /**

     * putInt() methods...

     */

    public final RenderBuffer putInt(int pos, int x) {

        // assert (baseAddress + pos % SIZEOF_INT == 0);

        unsafe.putInt(baseAddress + pos, x);

        return this;

    }

    public final RenderBuffer putInt(int x) {

        // assert (position() % SIZEOF_INT == 0);

        unsafe.putInt(curAddress, x);

        curAddress += SIZEOF_INT;

        return this;

    }

    public RenderBuffer put(int[] x) {

        return put(x, 0, x.length);

    }

    public RenderBuffer put(int[] x, int offset, int length) {

        // assert (position() % SIZEOF_INT == 0);

        if (length > COPY_FROM_ARRAY_THRESHOLD) {

            long offsetInBytes = offset * SIZEOF_INT;

            long lengthInBytes = length * SIZEOF_INT;

            copyFromArray(x, offsetInBytes, curAddress, lengthInBytes);

            position(position() + lengthInBytes);

        } else {

            int end = offset + length;

            for (int i = offset; i < end; i++) {

                putInt(x[i]);

            }

        }

        return this;

    }

    /**

     * putFloat() methods...

     */

    public final RenderBuffer putFloat(float x) {

        // assert (position() % SIZEOF_FLOAT == 0);

        unsafe.putFloat(curAddress, x);

        curAddress += SIZEOF_FLOAT;

        return this;

    }

    public RenderBuffer put(float[] x) {

        return put(x, 0, x.length);

    }

    public RenderBuffer put(float[] x, int offset, int length) {

        // assert (position() % SIZEOF_FLOAT == 0);

        if (length > COPY_FROM_ARRAY_THRESHOLD) {

            long offsetInBytes = offset * SIZEOF_FLOAT;

            long lengthInBytes = length * SIZEOF_FLOAT;

            copyFromArray(x, offsetInBytes, curAddress, lengthInBytes);

            position(position() + lengthInBytes);

        } else {

            int end = offset + length;

            for (int i = offset; i < end; i++) {

                putFloat(x[i]);

            }

        }

        return this;

    }

    /**

     * putLong() methods...

     */

    public final RenderBuffer putLong(long x) {

        // assert (position() % SIZEOF_LONG == 0);

        unsafe.putLong(curAddress, x);

        curAddress += SIZEOF_LONG;

        return this;

    }

    public RenderBuffer put(long[] x) {

        return put(x, 0, x.length);

    }

    public RenderBuffer put(long[] x, int offset, int length) {

        // assert (position() % SIZEOF_LONG == 0);

        if (length > COPY_FROM_ARRAY_THRESHOLD) {

            long offsetInBytes = offset * SIZEOF_LONG;

            long lengthInBytes = length * SIZEOF_LONG;

            copyFromArray(x, offsetInBytes, curAddress, lengthInBytes);

            position(position() + lengthInBytes);

        } else {

            int end = offset + length;

            for (int i = offset; i < end; i++) {

                putLong(x[i]);

            }

        }

        return this;

    }

    /**

     * putDouble() method(s)...

     */

    public final RenderBuffer putDouble(double x) {

        // assert (position() % SIZEOF_DOUBLE == 0);

        unsafe.putDouble(curAddress, x);

        curAddress += SIZEOF_DOUBLE;

        return this;

    }

}