1 /* 2 * Copyright (c) 2009, 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 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 package org.graalvm.compiler.asm; 24 25 import java.nio.ByteBuffer; 26 import java.nio.ByteOrder; 27 import java.util.Arrays; 28 29 /** 30 * Code buffer management for the assembler. 31 */ 32 final class Buffer { 33 34 protected ByteBuffer data; 35 36 Buffer(ByteOrder order) { 37 data = ByteBuffer.allocate(AsmOptions.InitialCodeBufferSize); 38 data.order(order); 39 } 40 41 public int position() { 42 return data.position(); 43 } 44 45 public void setPosition(int position) { 46 assert position >= 0 && position <= data.limit(); 47 data.position(position); 48 } 49 50 /** 51 * Closes this buffer. Any further operations on a closed buffer will result in a 52 * {@link NullPointerException}. 53 * 54 * @param trimmedCopy if {@code true}, then a copy of the underlying byte array up to (but not 55 * including) {@code position()} is returned 56 * @return the data in this buffer or a trimmed copy if {@code trimmedCopy} is {@code true} 57 */ 58 public byte[] close(boolean trimmedCopy) { 59 byte[] result = data.array(); 60 if (trimmedCopy) { 61 // Make a copy even if result.length == data.position() since 62 // the API for trimmedCopy states a copy is always made 63 result = Arrays.copyOf(result, data.position()); 64 } 65 data = null; 66 return result; 67 } 68 69 public byte[] copyData(int start, int end) { 70 if (data == null) { 71 return null; 72 } 73 return Arrays.copyOfRange(data.array(), start, end); 74 } 75 76 /** 77 * Copies the data from this buffer into a given array. 78 * 79 * @param dst the destination array 80 * @param off starting position in {@code dst} 81 * @param len number of bytes to copy 82 */ 83 public void copyInto(byte[] dst, int off, int len) { 84 System.arraycopy(data.array(), 0, dst, off, len); 85 } 86 87 protected void ensureSize(int length) { 88 if (length >= data.limit()) { 89 byte[] newBuf = Arrays.copyOf(data.array(), length * 4); 90 ByteBuffer newData = ByteBuffer.wrap(newBuf); 91 newData.order(data.order()); 92 newData.position(data.position()); 93 data = newData; 94 } 95 } 96 97 public void emitBytes(byte[] arr, int off, int len) { 98 ensureSize(data.position() + len); 99 data.put(arr, off, len); 100 } 101 102 public void emitByte(int b) { 103 assert NumUtil.isUByte(b) || NumUtil.isByte(b); 104 ensureSize(data.position() + 1); 105 data.put((byte) (b & 0xFF)); 106 } 107 108 public void emitShort(int b) { 109 assert NumUtil.isUShort(b) || NumUtil.isShort(b); 110 ensureSize(data.position() + 2); 111 data.putShort((short) b); 112 } 113 114 public void emitInt(int b) { 115 ensureSize(data.position() + 4); 116 data.putInt(b); 117 } 118 119 public void emitLong(long b) { 120 ensureSize(data.position() + 8); 121 data.putLong(b); 122 } 123 124 public void emitBytes(byte[] arr, int pos) { 125 final int len = arr.length; 126 ensureSize(pos + len); 127 // Write directly into the underlying array so as to not 128 // change the ByteBuffer's position 129 System.arraycopy(arr, 0, data.array(), pos, len); 130 } 131 132 public void emitByte(int b, int pos) { 133 assert NumUtil.isUByte(b) || NumUtil.isByte(b); 134 ensureSize(pos + 1); 135 data.put(pos, (byte) (b & 0xFF)); 136 } 137 138 public void emitShort(int b, int pos) { 139 assert NumUtil.isUShort(b) || NumUtil.isShort(b); 140 ensureSize(pos + 2); 141 data.putShort(pos, (short) b).position(); 142 } 143 144 public void emitInt(int b, int pos) { 145 ensureSize(pos + 4); 146 data.putInt(pos, b).position(); 147 } 148 149 public void emitLong(long b, int pos) { 150 ensureSize(pos + 8); 151 data.putLong(pos, b).position(); 152 } 153 154 public int getByte(int pos) { 155 int b = data.get(pos); 156 return b & 0xff; 157 } 158 159 public int getShort(int pos) { 160 short s = data.getShort(pos); 161 return s & 0xffff; 162 } 163 164 public int getInt(int pos) { 165 return data.getInt(pos); 166 } 167 168 public void reset() { 169 data.clear(); 170 } 171 }