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 }