1 /*
2 * Copyright (c) 2015, 2019, 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 #ifndef SHARE_JFR_WRITERS_JFRENCODERS_HPP
26 #define SHARE_JFR_WRITERS_JFRENCODERS_HPP
27
28 #include "memory/allocation.hpp"
29 #include "utilities/bytes.hpp"
30 #include "utilities/debug.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 //
34 // The Encoding policy prescribes a template
35 // method taking a first parameter of type T.
36 // This is the value to be encoded. The second
37 // parameter is a memory address - where to write
38 // the encoded value.
39 // The encoder method(s) should return the
40 // number of bytes encoded into that memory address.
41 //
42 // template <typename T>
43 // size_t encoder(T value, u1* dest);
44 //
45 // The caller ensures the destination
46 // address is not null and that T can be fitted
47 // in encoded form.
48 //
49
50 // Encoding policy classes
51
52 class BigEndianEncoderImpl {
53 public:
54 template <typename T>
55 static size_t encode(T value, u1* dest);
56
57 template <typename T>
58 static size_t encode(const T* src, size_t len, u1* dest);
59
60 template <typename T>
61 static size_t encode_padded(T value, u1* dest);
62
63 template <typename T>
64 static size_t encode_padded(const T* src, size_t len, u1* dest);
65
66 };
67
68 template <typename T>
encode(T value,u1 * dest)69 inline size_t BigEndianEncoderImpl::encode(T value, u1* dest) {
70 assert(dest != NULL, "invariant");
71 switch (sizeof(T)) {
72 case 1: {
73 ShouldNotReachHere();
74 return 0;
75 }
76 case 2: {
77 Bytes::put_Java_u2(dest, value);
78 return 2;
79 }
80 case 4: {
81 Bytes::put_Java_u4(dest, value);
82 return 4;
83 }
84 case 8: {
85 Bytes::put_Java_u8(dest, value);
86 return 8;
87 }
88 }
89 ShouldNotReachHere();
90 return 0;
91 }
92
93 template <typename T>
encode(const T * src,size_t len,u1 * dest)94 inline size_t BigEndianEncoderImpl::encode(const T* src, size_t len, u1* dest) {
95 assert(dest != NULL, "invariant");
96 assert(len >= 1, "invariant");
97 if (1 == sizeof(T)) {
98 memcpy(dest, src, len);
99 return len;
100 }
101 size_t size = encode(*src, dest);
102 if (len > 1) {
103 for (size_t i = 1; i < len; ++i) {
104 size += encode(*(src + i), dest + size);
105 }
106 }
107 return size;
108 }
109
110 template <typename T>
encode_padded(T value,u1 * dest)111 inline size_t BigEndianEncoderImpl::encode_padded(T value, u1* dest) {
112 return encode(value, dest);
113 }
114
115 template <typename T>
encode_padded(const T * src,size_t len,u1 * dest)116 inline size_t BigEndianEncoderImpl::encode_padded(const T* src, size_t len, u1* dest) {
117 assert(dest != NULL, "invariant");
118 assert(len >= 1, "invariant");
119 if (1 == sizeof(T)) {
120 memcpy(dest, src, len);
121 return len;
122 }
123 size_t size = encode_padded(*src, dest);
124 if (len > 1) {
125 for (size_t i = 1; i < len; ++i) {
126 size += encode_padded(*(src + i), dest + size);
127 }
128 }
129 return size;
130 }
131
132
133 // The Varint128 encoder implements encoding according to
134 // msb(it) 128bit encoding (1 encode bit | 7 value bits),
135 // using least significant byte order.
136 //
137 // Example (little endian platform):
138 // Value: 25674
139 // Binary: 00000000 0000000 01100100 01001010
140 // Varint encoded (3 bytes):
141 // Value: 13289473
142 // Varint encoded: 11001010 11001000 00000001
143 //
144
145 class Varint128EncoderImpl {
146 private:
147 template <typename T>
148 static u8 to_u8(T value);
149
150 public:
151 template <typename T>
152 static size_t encode(T value, u1* dest);
153
154 template <typename T>
155 static size_t encode(const T* src, size_t len, u1* dest);
156
157 template <typename T>
158 static size_t encode_padded(T value, u1* dest);
159
160 template <typename T>
161 static size_t encode_padded(const T* src, size_t len, u1* dest);
162
163 };
164
165 template <typename T>
to_u8(T value)166 inline u8 Varint128EncoderImpl::to_u8(T value) {
167 switch(sizeof(T)) {
168 case 1:
169 return static_cast<u8>(static_cast<u1>(value) & static_cast<u1>(0xff));
170 case 2:
171 return static_cast<u8>(static_cast<u2>(value) & static_cast<u2>(0xffff));
172 case 4:
173 return static_cast<u8>(static_cast<u4>(value) & static_cast<u4>(0xffffffff));
174 case 8:
175 return static_cast<u8>(value);
176 default:
177 fatal("unsupported type");
178 }
179 return 0;
180 }
181
182 static const u1 ext_bit = 0x80;
183 #define GREATER_THAN_OR_EQUAL_TO_128(v) (((u8)(~(ext_bit - 1)) & (v)))
184 #define LESS_THAN_128(v) !GREATER_THAN_OR_EQUAL_TO_128(v)
185
186 template <typename T>
encode(T value,u1 * dest)187 inline size_t Varint128EncoderImpl::encode(T value, u1* dest) {
188 assert(dest != NULL, "invariant");
189
190 const u8 v = to_u8(value);
191
192 if (LESS_THAN_128(v)) {
193 *dest = static_cast<u1>(v); // set bit 0-6, no extension
194 return 1;
195 }
196 *dest = static_cast<u1>(v | ext_bit); // set bit 0-6, with extension
197 if (LESS_THAN_128(v >> 7)) {
198 *(dest + 1) = static_cast<u1>(v >> 7); // set bit 7-13, no extension
199 return 2;
200 }
201 *(dest + 1) = static_cast<u1>((v >> 7) | ext_bit); // set bit 7-13, with extension
202 if (LESS_THAN_128(v >> 14)) {
203 *(dest + 2) = static_cast<u1>(v >> 14); // set bit 14-20, no extension
204 return 3;
205 }
206 *(dest + 2) = static_cast<u1>((v >> 14) | ext_bit); // set bit 14-20, with extension
207 if (LESS_THAN_128(v >> 21)) {
208 *(dest + 3) = static_cast<u1>(v >> 21); // set bit 21-27, no extension
209 return 4;
210 }
211 *(dest + 3) = static_cast<u1>((v >> 21) | ext_bit); // set bit 21-27, with extension
212 if (LESS_THAN_128(v >> 28)) {
213 *(dest + 4) = static_cast<u1>(v >> 28); // set bit 28-34, no extension
214 return 5;
215 }
216 *(dest + 4) = static_cast<u1>((v >> 28) | ext_bit); // set bit 28-34, with extension
217 if (LESS_THAN_128(v >> 35)) {
218 *(dest + 5) = static_cast<u1>(v >> 35); // set bit 35-41, no extension
219 return 6;
220 }
221 *(dest + 5) = static_cast<u1>((v >> 35) | ext_bit); // set bit 35-41, with extension
222 if (LESS_THAN_128(v >> 42)) {
223 *(dest + 6) = static_cast<u1>(v >> 42); // set bit 42-48, no extension
224 return 7;
225 }
226 *(dest + 6) = static_cast<u1>((v >> 42) | ext_bit); // set bit 42-48, with extension
227 if (LESS_THAN_128(v >> 49)) {
228 *(dest + 7) = static_cast<u1>(v >> 49); // set bit 49-55, no extension
229 return 8;
230 }
231 *(dest + 7) = static_cast<u1>((v >> 49) | ext_bit); // set bit 49-55, with extension
232 // no need to extend since only 64 bits allowed.
233 *(dest + 8) = static_cast<u1>(v >> 56); // set bit 56-63
234 return 9;
235 }
236
237 template <typename T>
encode(const T * src,size_t len,u1 * dest)238 inline size_t Varint128EncoderImpl::encode(const T* src, size_t len, u1* dest) {
239 assert(dest != NULL, "invariant");
240 assert(len >= 1, "invariant");
241 size_t size = encode(*src, dest);
242 if (len > 1) {
243 for (size_t i = 1; i < len; ++i) {
244 size += encode(*(src + i), dest + size);
245 }
246 }
247 return size;
248 }
249
250 template <typename T>
encode_padded(T value,u1 * dest)251 inline size_t Varint128EncoderImpl::encode_padded(T value, u1* dest) {
252 assert(dest != NULL, "invariant");
253 const u8 v = to_u8(value);
254 switch (sizeof(T)) {
255 case 1:
256 dest[0] = static_cast<u1>(v);
257 return 1;
258 case 2:
259 dest[0] = static_cast<u1>(v | 0x80);
260 dest[1] = static_cast<u1>(v >> 7);
261 return 2;
262 case 4:
263 dest[0] = static_cast<u1>(v | 0x80);
264 dest[1] = static_cast<u1>(v >> 7 | 0x80);
265 dest[2] = static_cast<u1>(v >> 14 | 0x80);
266 dest[3] = static_cast<u1>(v >> 21);
267 return 4;
268 case 8:
269 dest[0] = static_cast<u1>(v | 0x80);
270 dest[1] = static_cast<u1>(v >> 7 | 0x80);
271 dest[2] = static_cast<u1>(v >> 14 | 0x80);
272 dest[3] = static_cast<u1>(v >> 21 | 0x80);
273 dest[4] = static_cast<u1>(v >> 28 | 0x80);
274 dest[5] = static_cast<u1>(v >> 35 | 0x80);
275 dest[6] = static_cast<u1>(v >> 42 | 0x80);
276 dest[7] = static_cast<u1>(v >> 49);
277 return 8;
278 default:
279 ShouldNotReachHere();
280 }
281 return 0;
282 }
283
284
285 template <typename T>
encode_padded(const T * src,size_t len,u1 * dest)286 inline size_t Varint128EncoderImpl::encode_padded(const T* src, size_t len, u1* dest) {
287 assert(dest != NULL, "invariant");
288 assert(len >= 1, "invariant");
289 size_t size = encode_padded(*src, dest);
290 if (len > 1) {
291 for (size_t i = 1; i < len; ++i) {
292 size += encode_padded(*(src + i), dest + size);
293 }
294 }
295 return size;
296 }
297
298 #endif // SHARE_JFR_WRITERS_JFRENCODERS_HPP
299