1 /*
2 * Copyright (c) 2009, 2018, 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
25 package org.graalvm.compiler.asm;
26
27 import java.nio.ByteBuffer;
28 import java.nio.ByteOrder;
29 import java.util.Arrays;
30
31 import org.graalvm.compiler.core.common.NumUtil;
32 import org.graalvm.compiler.serviceprovider.BufferUtil;
33
34 /**
35 * Code buffer management for the assembler.
36 */
37 final class Buffer {
38
39 protected ByteBuffer data;
40
41 Buffer(ByteOrder order) {
42 data = ByteBuffer.allocate(AsmOptions.InitialCodeBufferSize);
43 data.order(order);
44 }
45
46 public int position() {
47 return data.position();
48 }
49
50 public void setPosition(int position) {
51 assert position >= 0 && position <= data.limit();
52 BufferUtil.asBaseBuffer(data).position(position);
53 }
54
55 /**
56 * Closes this buffer. Any further operations on a closed buffer will result in a
57 * {@link NullPointerException}.
58 *
59 * @param trimmedCopy if {@code true}, then a copy of the underlying byte array up to (but not
60 * including) {@code position()} is returned
61 * @return the data in this buffer or a trimmed copy if {@code trimmedCopy} is {@code true}
62 */
63 public byte[] close(boolean trimmedCopy) {
64 byte[] result = data.array();
65 if (trimmedCopy) {
66 // Make a copy even if result.length == data.position() since
67 // the API for trimmedCopy states a copy is always made
68 result = Arrays.copyOf(result, data.position());
69 }
70 data = null;
71 return result;
72 }
73
74 public byte[] copyData(int start, int end) {
75 if (data == null) {
76 return null;
77 }
78 return Arrays.copyOfRange(data.array(), start, end);
79 }
80
81 /**
82 * Copies the data from this buffer into a given array.
83 *
84 * @param dst the destination array
85 * @param off starting position in {@code dst}
86 * @param len number of bytes to copy
87 */
88 public void copyInto(byte[] dst, int off, int len) {
89 System.arraycopy(data.array(), 0, dst, off, len);
90 }
91
92 protected void ensureSize(int length) {
93 if (length >= data.limit()) {
94 byte[] newBuf = Arrays.copyOf(data.array(), length * 4);
95 ByteBuffer newData = ByteBuffer.wrap(newBuf);
96 newData.order(data.order());
97 BufferUtil.asBaseBuffer(newData).position(data.position());
98 data = newData;
99 }
100 }
101
102 public void emitBytes(byte[] arr, int off, int len) {
103 ensureSize(data.position() + len);
104 data.put(arr, off, len);
105 }
106
107 public void emitByte(int b) {
108 assert NumUtil.isUByte(b) || NumUtil.isByte(b);
109 ensureSize(data.position() + 1);
110 data.put((byte) (b & 0xFF));
111 }
112
113 public void emitShort(int b) {
114 assert NumUtil.isUShort(b) || NumUtil.isShort(b);
115 ensureSize(data.position() + 2);
116 data.putShort((short) b);
117 }
118
119 public void emitInt(int b) {
120 ensureSize(data.position() + 4);
121 data.putInt(b);
122 }
123
124 public void emitLong(long b) {
125 ensureSize(data.position() + 8);
126 data.putLong(b);
127 }
128
129 public void emitBytes(byte[] arr, int pos) {
130 final int len = arr.length;
131 ensureSize(pos + len);
132 // Write directly into the underlying array so as to not
133 // change the ByteBuffer's position
134 System.arraycopy(arr, 0, data.array(), pos, len);
135 }
136
137 public void emitByte(int b, int pos) {
138 assert NumUtil.isUByte(b) || NumUtil.isByte(b);
139 ensureSize(pos + 1);
140 data.put(pos, (byte) (b & 0xFF));
141 }
142
143 public void emitShort(int b, int pos) {
144 assert NumUtil.isUShort(b) || NumUtil.isShort(b);
145 ensureSize(pos + 2);
146 data.putShort(pos, (short) b).position();
147 }
148
149 public void emitInt(int b, int pos) {
150 ensureSize(pos + 4);
151 data.putInt(pos, b).position();
152 }
153
154 public void emitLong(long b, int pos) {
155 ensureSize(pos + 8);
156 data.putLong(pos, b).position();
157 }
158
159 public int getByte(int pos) {
160 int b = data.get(pos);
161 return b & 0xff;
162 }
163
164 public int getShort(int pos) {
165 short s = data.getShort(pos);
166 return s & 0xffff;
167 }
168
169 public int getInt(int pos) {
170 return data.getInt(pos);
171 }
172
173 public void reset() {
174 BufferUtil.asBaseBuffer(data).clear();
175 }
176 }