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1 // Copyright 2006-2008 the V8 project authors. All rights reserved. | 1 // Copyright 2006-2008 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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167 } | 167 } |
168 | 168 |
169 // Extracts the bit field from the value. | 169 // Extracts the bit field from the value. |
170 static T decode(uint32_t value) { | 170 static T decode(uint32_t value) { |
171 return static_cast<T>((value >> shift) & ((1U << (size)) - 1)); | 171 return static_cast<T>((value >> shift) & ((1U << (size)) - 1)); |
172 } | 172 } |
173 }; | 173 }; |
174 | 174 |
175 | 175 |
176 // ---------------------------------------------------------------------------- | 176 // ---------------------------------------------------------------------------- |
177 // Support for compressed, machine-independent encoding | |
178 // and decoding of integer values of arbitrary size. | |
179 | |
180 // Encoding and decoding from/to a buffer at position p; | |
181 // the result is the position after the encoded integer. | |
182 // Small signed integers in the range -64 <= x && x < 64 | |
183 // are encoded in 1 byte; larger values are encoded in 2 | |
184 // or more bytes. At most sizeof(int) + 1 bytes are used | |
185 // in the worst case. | |
186 byte* EncodeInt(byte* p, int x); | |
187 byte* DecodeInt(byte* p, int* x); | |
188 | |
189 | |
190 // Encoding and decoding from/to a buffer at position p - 1 | |
191 // moving backward; the result is the position of the last | |
192 // byte written. These routines are useful to read/write | |
193 // into a buffer starting at the end of the buffer. | |
194 byte* EncodeUnsignedIntBackward(byte* p, unsigned int x); | |
195 | |
196 // The decoding function is inlined since its performance is | |
197 // important to mark-sweep garbage collection. | |
198 inline byte* DecodeUnsignedIntBackward(byte* p, unsigned int* x) { | |
199 byte b = *--p; | |
200 if (b >= 128) { | |
201 *x = static_cast<unsigned int>(b) - 128; | |
202 return p; | |
203 } | |
204 unsigned int r = static_cast<unsigned int>(b); | |
205 unsigned int s = 7; | |
206 b = *--p; | |
207 while (b < 128) { | |
208 r |= static_cast<unsigned int>(b) << s; | |
209 s += 7; | |
210 b = *--p; | |
211 } | |
212 // b >= 128 | |
213 *x = r | ((static_cast<unsigned int>(b) - 128) << s); | |
214 return p; | |
215 } | |
216 | |
217 | |
218 // ---------------------------------------------------------------------------- | |
219 // Hash function. | 177 // Hash function. |
220 | 178 |
221 uint32_t ComputeIntegerHash(uint32_t key); | 179 uint32_t ComputeIntegerHash(uint32_t key); |
222 | 180 |
223 | 181 |
224 // ---------------------------------------------------------------------------- | 182 // ---------------------------------------------------------------------------- |
225 // I/O support. | 183 // I/O support. |
226 | 184 |
227 // Our version of printf(). Avoids compilation errors that we get | 185 // Our version of printf(). Avoids compilation errors that we get |
228 // with standard printf when attempting to print pointers, etc. | 186 // with standard printf when attempting to print pointers, etc. |
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583 } | 541 } |
584 } | 542 } |
585 | 543 |
586 | 544 |
587 // Calculate 10^exponent. | 545 // Calculate 10^exponent. |
588 int TenToThe(int exponent); | 546 int TenToThe(int exponent); |
589 | 547 |
590 } } // namespace v8::internal | 548 } } // namespace v8::internal |
591 | 549 |
592 #endif // V8_UTILS_H_ | 550 #endif // V8_UTILS_H_ |
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