/**
 * Copyright 2013, Landz and its contributors. All rights reserved.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package jnr.x86asm;

import java.nio.ByteBuffer;

/**
 * Class used to determine size of trampoline and as trampoline writer.
 */
final class TrampolineWriter {
    // Size of trampoline

    public static final int TRAMPOLINE_JMP = 6;
    public static final int TRAMPOLINE_ADDR = 8;
    public static final int TRAMPOLINE_SIZE = TRAMPOLINE_JMP + TRAMPOLINE_ADDR;

    // Write trampoline into code at address @a code that will jump to @a target.
    static void writeTrampoline(ByteBuffer buf, long target) {
        // Jmp.
        buf.put((byte) 0xFF);

        // ModM (RIP addressing).
        buf.put((byte) 0x25);
        // Offset (zero).
        buf.putInt(0);
        // Absolute address.
        buf.putLong(target);
    }
}