1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 package jdk.experimental.bytecode;
  25 
  26 import java.util.function.Consumer;
  27 
  28 public class GrowableByteBuffer {
  29 
  30     public GrowableByteBuffer() {
  31     }
  32 
  33     byte[] elems = new byte[64];
  34     int offset = 0;
  35 
  36     public GrowableByteBuffer writeByte(int b) {
  37         return writeBytes(1, b);
  38     }
  39 
  40     public GrowableByteBuffer writeChar(int x) {
  41         return writeBytes(2, x);
  42     }
  43 
  44     public GrowableByteBuffer writeInt(int x) {
  45         return writeBytes(4, x);
  46     }
  47 
  48     public GrowableByteBuffer writeFloat(float x) {
  49         return writeInt(Float.floatToIntBits(x));
  50     }
  51 
  52     public GrowableByteBuffer writeLong(long x) {
  53         return writeBytes(8, x);
  54     }
  55 
  56     public GrowableByteBuffer writeDouble(double x) {
  57         writeLong(Double.doubleToLongBits(x));
  58         return this;
  59     }
  60 
  61     public GrowableByteBuffer writeBytes(byte[] barr) {
  62         expandIfNeeded(barr.length);
  63         System.arraycopy(barr, 0, elems, offset, barr.length);
  64         offset += barr.length;
  65         return this;
  66     }
  67 
  68     public GrowableByteBuffer writeBytes(GrowableByteBuffer bb) {
  69         expandIfNeeded(bb.offset);
  70         System.arraycopy(bb.elems, 0, elems, offset, bb.offset);
  71         offset += bb.offset;
  72         return this;
  73     }
  74 
  75     public GrowableByteBuffer withOffset(int offset, Consumer<GrowableByteBuffer> actions) {
  76         int prevOffset = this.offset;
  77         this.offset = offset;
  78         actions.accept(this);
  79         this.offset = prevOffset;
  80         return this;
  81     }
  82 
  83     private GrowableByteBuffer writeBytes(int size, long x) {
  84         expandIfNeeded(size);
  85         for (int i = 0; i < size; i++) {
  86             elems[offset++] = (byte) ((x >> 8 * (size - i - 1)) & 0xFF);
  87         }
  88         return this;
  89     }
  90 
  91     void expandIfNeeded(int increment) {
  92         if (offset + increment > elems.length) {
  93             int newsize = elems.length * 2;
  94             while (offset + increment > newsize) {
  95                 newsize *= 2;
  96             }
  97             byte[] newelems = new byte[newsize];
  98             System.arraycopy(elems, 0, newelems, 0, offset);
  99             elems = newelems;
 100         }
 101     }
 102 
 103     public byte[] bytes() {
 104         byte[] bytes = new byte[offset];
 105         System.arraycopy(elems, 0, bytes, 0, offset);
 106         return bytes;
 107     }
 108 }