UnsafeArrayTypeWriter.java revision 12651:6ef01bd40ce2
1169092Sdeischen/* 2169092Sdeischen * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved. 3169092Sdeischen * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4164190Sjkoshy * 5164190Sjkoshy * This code is free software; you can redistribute it and/or modify it 6164190Sjkoshy * under the terms of the GNU General Public License version 2 only, as 7164190Sjkoshy * published by the Free Software Foundation. 8164190Sjkoshy * 9164190Sjkoshy * This code is distributed in the hope that it will be useful, but WITHOUT 10164190Sjkoshy * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11164190Sjkoshy * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12164190Sjkoshy * version 2 for more details (a copy is included in the LICENSE file that 13164190Sjkoshy * accompanied this code). 14164190Sjkoshy * 15164190Sjkoshy * You should have received a copy of the GNU General Public License version 16164190Sjkoshy * 2 along with this work; if not, write to the Free Software Foundation, 17164190Sjkoshy * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18164190Sjkoshy * 19164190Sjkoshy * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20164190Sjkoshy * or visit www.oracle.com if you need additional information or have any 21164190Sjkoshy * questions. 22164190Sjkoshy */ 23164190Sjkoshypackage org.graalvm.compiler.core.common.util; 24164190Sjkoshy 25164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asS1; 26164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asS2; 27164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asS4; 28164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asU1; 29164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asU2; 30164190Sjkoshyimport static org.graalvm.compiler.core.common.util.TypeConversion.asU4; 31164190Sjkoshyimport sun.misc.Unsafe; 32164190Sjkoshy 33164190Sjkoshy/** 34164190Sjkoshy * Provides low-level sequential write access to a byte[] array for signed and unsigned values of 35164190Sjkoshy * size 1, 2, 4, and 8 bytes. To avoid copying an array when the buffer size is no longer 36164190Sjkoshy * sufficient, the buffer is split into chunks of a fixed size. 37164190Sjkoshy * 38164190Sjkoshy * The flag {@code supportsUnalignedMemoryAccess} must be set according to the capabilities of the 39164190Sjkoshy * hardware architecture: the value {@code true} allows more efficient memory access on 40164190Sjkoshy * architectures that support unaligned memory accesses; the value {@code false} is the safe 41164190Sjkoshy * fallback that works on every hardware. 42210345Skaiw */ 43165535Sjkoshypublic abstract class UnsafeArrayTypeWriter implements TypeWriter { 44210345Skaiw 45164190Sjkoshy private static final int MIN_CHUNK_LENGTH = 200; 46210345Skaiw private static final int MAX_CHUNK_LENGTH = 16000; 47164190Sjkoshy 48164190Sjkoshy static class Chunk { 49164190Sjkoshy protected final byte[] data; 50164190Sjkoshy protected int size; 51164190Sjkoshy protected Chunk next; 52164190Sjkoshy 53164190Sjkoshy protected Chunk(int arrayLength) { 54164190Sjkoshy data = new byte[arrayLength]; 55164190Sjkoshy } 56164190Sjkoshy } 57164190Sjkoshy 58164190Sjkoshy protected final Chunk firstChunk; 59164190Sjkoshy protected Chunk writeChunk; 60164190Sjkoshy protected int totalSize; 61164190Sjkoshy 62164190Sjkoshy public static UnsafeArrayTypeWriter create(boolean supportsUnalignedMemoryAccess) { 63164190Sjkoshy if (supportsUnalignedMemoryAccess) { 64164190Sjkoshy return new UnalignedUnsafeArrayTypeWriter(); 65164190Sjkoshy } else { 66164190Sjkoshy return new AlignedUnsafeArrayTypeWriter(); 67164190Sjkoshy } 68164190Sjkoshy } 69164190Sjkoshy 70164190Sjkoshy protected UnsafeArrayTypeWriter() { 71164190Sjkoshy firstChunk = new Chunk(MIN_CHUNK_LENGTH); 72164190Sjkoshy writeChunk = firstChunk; 73164190Sjkoshy } 74164190Sjkoshy 75164190Sjkoshy @Override 76164190Sjkoshy public final long getBytesWritten() { 77164190Sjkoshy return totalSize; 78164190Sjkoshy } 79164190Sjkoshy 80164190Sjkoshy /** 81164190Sjkoshy * Copies the buffer into the provided byte[] array of length {@link #getBytesWritten()}. 82164190Sjkoshy */ 83164190Sjkoshy public final byte[] toArray(byte[] result) { 84164190Sjkoshy assert result.length == totalSize; 85164190Sjkoshy int resultIdx = 0; 86164190Sjkoshy for (Chunk cur = firstChunk; cur != null; cur = cur.next) { 87164190Sjkoshy System.arraycopy(cur.data, 0, result, resultIdx, cur.size); 88164190Sjkoshy resultIdx += cur.size; 89164190Sjkoshy } 90164190Sjkoshy assert resultIdx == totalSize; 91164190Sjkoshy return result; 92164190Sjkoshy } 93164190Sjkoshy 94164190Sjkoshy @Override 95164190Sjkoshy public final void putS1(long value) { 96169092Sdeischen long offset = writeOffset(Byte.BYTES); 97169092Sdeischen UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset, asS1(value)); 98169092Sdeischen } 99169092Sdeischen 100164190Sjkoshy @Override 101164190Sjkoshy public final void putU1(long value) { 102164190Sjkoshy long offset = writeOffset(Byte.BYTES); 103164190Sjkoshy UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset, asU1(value)); 104164190Sjkoshy } 105164190Sjkoshy 106 @Override 107 public final void putU2(long value) { 108 putS2(asU2(value)); 109 } 110 111 @Override 112 public final void putU4(long value) { 113 putS4(asU4(value)); 114 } 115 116 protected long writeOffset(int writeBytes) { 117 if (writeChunk.size + writeBytes >= writeChunk.data.length) { 118 Chunk newChunk = new Chunk(Math.min(writeChunk.data.length * 2, MAX_CHUNK_LENGTH)); 119 writeChunk.next = newChunk; 120 writeChunk = newChunk; 121 } 122 123 assert Unsafe.ARRAY_BYTE_INDEX_SCALE == 1; 124 long result = writeChunk.size + Unsafe.ARRAY_BYTE_BASE_OFFSET; 125 126 totalSize += writeBytes; 127 writeChunk.size += writeBytes; 128 assert writeChunk.size <= writeChunk.data.length; 129 130 return result; 131 } 132} 133 134final class UnalignedUnsafeArrayTypeWriter extends UnsafeArrayTypeWriter { 135 @Override 136 public void putS2(long value) { 137 long offset = writeOffset(Short.BYTES); 138 UnsafeAccess.UNSAFE.putShort(writeChunk.data, offset, asS2(value)); 139 } 140 141 @Override 142 public void putS4(long value) { 143 long offset = writeOffset(Integer.BYTES); 144 UnsafeAccess.UNSAFE.putInt(writeChunk.data, offset, asS4(value)); 145 } 146 147 @Override 148 public void putS8(long value) { 149 long offset = writeOffset(Long.BYTES); 150 UnsafeAccess.UNSAFE.putLong(writeChunk.data, offset, value); 151 } 152} 153 154final class AlignedUnsafeArrayTypeWriter extends UnsafeArrayTypeWriter { 155 @Override 156 public void putS2(long value) { 157 long offset = writeOffset(Short.BYTES); 158 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 0, (byte) (value >> 0)); 159 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 1, (byte) (value >> 8)); 160 } 161 162 @Override 163 public void putS4(long value) { 164 long offset = writeOffset(Integer.BYTES); 165 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 0, (byte) (value >> 0)); 166 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 1, (byte) (value >> 8)); 167 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 2, (byte) (value >> 16)); 168 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 3, (byte) (value >> 24)); 169 } 170 171 @Override 172 public void putS8(long value) { 173 long offset = writeOffset(Long.BYTES); 174 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 0, (byte) (value >> 0)); 175 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 1, (byte) (value >> 8)); 176 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 2, (byte) (value >> 16)); 177 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 3, (byte) (value >> 24)); 178 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 4, (byte) (value >> 32)); 179 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 5, (byte) (value >> 40)); 180 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 6, (byte) (value >> 48)); 181 UnsafeAccess.UNSAFE.putByte(writeChunk.data, offset + 7, (byte) (value >> 56)); 182 } 183} 184