1 /*
   2  * Copyright (c) 2014, 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 License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.internal.jimage;
  27 
  28 import java.nio.ByteBuffer;
  29 import java.nio.ByteOrder;
  30 import java.util.Arrays;
  31 
  32 class ImageStream {
  33     private ByteBuffer buffer;
  34 
  35     ImageStream() {
  36         this(1024, ByteOrder.nativeOrder());
  37     }
  38 
  39     ImageStream(int size) {
  40         this(size, ByteOrder.nativeOrder());
  41     }
  42 
  43     ImageStream(byte[] bytes) {
  44        this(bytes, ByteOrder.nativeOrder());
  45     }
  46 
  47     ImageStream(ByteOrder byteOrder) {
  48         this(1024, byteOrder);
  49     }
  50 
  51     ImageStream(int size, ByteOrder byteOrder) {
  52         buffer = ByteBuffer.allocate(size);
  53         buffer.order(byteOrder);
  54     }
  55 
  56     ImageStream(byte[] bytes, ByteOrder byteOrder) {
  57         buffer = ByteBuffer.wrap(bytes);
  58         buffer.order(byteOrder);
  59     }
  60 
  61     ImageStream(ByteBuffer buffer) {
  62         this.buffer = buffer;
  63     }
  64 
  65     ImageStream align(int alignment) {
  66         int padding = (getSize() - 1) & ((1 << alignment) - 1);
  67 
  68         for (int i = 0; i < padding; i++) {
  69             put((byte)0);
  70         }
  71 
  72         return this;
  73     }
  74 
  75     private void ensure(int needs) {
  76         assert 0 <= needs : "Negative needs";
  77 
  78         if (needs > buffer.remaining()) {
  79             byte[] bytes = buffer.array();
  80             ByteOrder byteOrder = buffer.order();
  81             int position = buffer.position();
  82             int newSize = needs <= bytes.length ? bytes.length << 1 : position + needs;
  83             buffer = ByteBuffer.allocate(newSize);
  84             buffer.order(byteOrder);
  85             buffer.put(bytes, 0, position);
  86         }
  87     }
  88 
  89     boolean hasByte() {
  90         return buffer.remaining() != 0;
  91     }
  92 
  93     boolean hasBytes(int needs) {
  94         return needs <= buffer.remaining();
  95     }
  96 
  97     void skip(int n) {
  98         assert 0 <= n : "Negative offset";
  99         buffer.position(buffer.position() + n);
 100     }
 101 
 102     int get() {
 103         return buffer.get() & 0xFF;
 104     }
 105 
 106     void get(byte bytes[], int offset, int size) {
 107         buffer.get(bytes, offset, size);
 108     }
 109 
 110     int getShort() {
 111         return buffer.getShort();
 112     }
 113 
 114     int getInt() {
 115         return buffer.getInt();
 116     }
 117 
 118     long getLong() {
 119         return buffer.getLong();
 120     }
 121 
 122     ImageStream put(byte byt) {
 123         ensure(1);
 124         buffer.put(byt);
 125 
 126         return this;
 127     }
 128 
 129     ImageStream put(int byt) {
 130         return put((byte)byt);
 131     }
 132 
 133     ImageStream put(byte bytes[], int offset, int size) {
 134         ensure(size);
 135         buffer.put(bytes, offset, size);
 136 
 137         return this;
 138     }
 139 
 140     ImageStream put(ImageStream stream) {
 141         put(stream.buffer.array(), 0, stream.buffer.position());
 142 
 143         return this;
 144     }
 145 
 146     ImageStream putShort(short value) {
 147         ensure(2);
 148         buffer.putShort(value);
 149 
 150         return this;
 151     }
 152 
 153     ImageStream putShort(int value) {
 154         return putShort((short)value);
 155     }
 156 
 157     ImageStream putInt(int value) {
 158         ensure(4);
 159         buffer.putInt(value);
 160 
 161         return this;
 162     }
 163 
 164     ImageStream putLong(long value) {
 165         ensure(8);
 166         buffer.putLong(value);
 167 
 168         return this;
 169     }
 170 
 171     ByteBuffer getBuffer() {
 172         return buffer;
 173     }
 174 
 175     int getPosition() {
 176         return buffer.position();
 177     }
 178 
 179     int getSize() {
 180         return buffer.position();
 181     }
 182 
 183     byte[] getBytes() {
 184         return buffer.array();
 185     }
 186 
 187     void setPosition(int offset) {
 188         buffer.position(offset);
 189     }
 190 
 191     byte[] toArray() {
 192         return Arrays.copyOf(buffer.array(), buffer.position());
 193     }
 194 }