/*

 * 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 org.graalvm.compiler.asm;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.util.Arrays;

import org.graalvm.compiler.core.common.NumUtil;

import org.graalvm.compiler.serviceprovider.BufferUtil;

/**

 * Code buffer management for the assembler.

 */

final class Buffer {

    protected ByteBuffer data;

    Buffer(ByteOrder order) {

        data = ByteBuffer.allocate(AsmOptions.InitialCodeBufferSize);

        data.order(order);

    }

    public int position() {

        return data.position();

    }

    public void setPosition(int position) {

        assert position >= 0 && position <= data.limit();

        BufferUtil.asBaseBuffer(data).position(position);

    }

    /**

     * Closes this buffer. Any further operations on a closed buffer will result in a

     * {@link NullPointerException}.

     *

     * @param trimmedCopy if {@code true}, then a copy of the underlying byte array up to (but not

     *            including) {@code position()} is returned

     * @return the data in this buffer or a trimmed copy if {@code trimmedCopy} is {@code true}

     */

    public byte[] close(boolean trimmedCopy) {

        byte[] result = data.array();

        if (trimmedCopy) {

            // Make a copy even if result.length == data.position() since

            // the API for trimmedCopy states a copy is always made

            result = Arrays.copyOf(result, data.position());

        }

        data = null;

        return result;

    }

    public byte[] copyData(int start, int end) {

        if (data == null) {

            return null;

        }

        return Arrays.copyOfRange(data.array(), start, end);

    }

    /**

     * Copies the data from this buffer into a given array.

     *

     * @param dst the destination array

     * @param off starting position in {@code dst}

     * @param len number of bytes to copy

     */

    public void copyInto(byte[] dst, int off, int len) {

        System.arraycopy(data.array(), 0, dst, off, len);

    }

    protected void ensureSize(int length) {

        if (length >= data.limit()) {

            byte[] newBuf = Arrays.copyOf(data.array(), length * 4);

            ByteBuffer newData = ByteBuffer.wrap(newBuf);

            newData.order(data.order());

            BufferUtil.asBaseBuffer(newData).position(data.position());

            data = newData;

        }

    }

    public void emitBytes(byte[] arr, int off, int len) {

        ensureSize(data.position() + len);

        data.put(arr, off, len);

    }

    public void emitByte(int b) {

        assert NumUtil.isUByte(b) || NumUtil.isByte(b);

        ensureSize(data.position() + 1);

        data.put((byte) (b & 0xFF));

    }

    public void emitShort(int b) {

        assert NumUtil.isUShort(b) || NumUtil.isShort(b);

        ensureSize(data.position() + 2);

        data.putShort((short) b);

    }

    public void emitInt(int b) {

        ensureSize(data.position() + 4);

        data.putInt(b);

    }

    public void emitLong(long b) {

        ensureSize(data.position() + 8);

        data.putLong(b);

    }

    public void emitBytes(byte[] arr, int pos) {

        final int len = arr.length;

        ensureSize(pos + len);

        // Write directly into the underlying array so as to not

        // change the ByteBuffer's position

        System.arraycopy(arr, 0, data.array(), pos, len);

    }

    public void emitByte(int b, int pos) {

        assert NumUtil.isUByte(b) || NumUtil.isByte(b);

        ensureSize(pos + 1);

        data.put(pos, (byte) (b & 0xFF));

    }

    public void emitShort(int b, int pos) {

        assert NumUtil.isUShort(b) || NumUtil.isShort(b);

        ensureSize(pos + 2);

        data.putShort(pos, (short) b).position();

    }

    public void emitInt(int b, int pos) {

        ensureSize(pos + 4);

        data.putInt(pos, b).position();

    }

    public void emitLong(long b, int pos) {

        ensureSize(pos + 8);

        data.putLong(pos, b).position();

    }

    public int getByte(int pos) {

        int b = data.get(pos);

        return b & 0xff;

    }

    public int getShort(int pos) {

        short s = data.getShort(pos);

        return s & 0xffff;

    }

    public int getInt(int pos) {

        return data.getInt(pos);

    }

    public void reset() {

        BufferUtil.asBaseBuffer(data).clear();

    }

}