christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame^] | 1 | // Copyright 2006-2008 Google Inc. All Rights Reserved. |
| 2 | // Redistribution and use in source and binary forms, with or without |
| 3 | // modification, are permitted provided that the following conditions are |
| 4 | // met: |
| 5 | // |
| 6 | // * Redistributions of source code must retain the above copyright |
| 7 | // notice, this list of conditions and the following disclaimer. |
| 8 | // * Redistributions in binary form must reproduce the above |
| 9 | // copyright notice, this list of conditions and the following |
| 10 | // disclaimer in the documentation and/or other materials provided |
| 11 | // with the distribution. |
| 12 | // * Neither the name of Google Inc. nor the names of its |
| 13 | // contributors may be used to endorse or promote products derived |
| 14 | // from this software without specific prior written permission. |
| 15 | // |
| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | |
| 28 | #ifndef V8_UTILS_H_ |
| 29 | #define V8_UTILS_H_ |
| 30 | |
| 31 | namespace v8 { namespace internal { |
| 32 | |
| 33 | // ---------------------------------------------------------------------------- |
| 34 | // General helper functions |
| 35 | |
| 36 | // Returns true iff x is a power of 2. Does not work for zero. |
| 37 | template <typename T> |
| 38 | static inline bool IsPowerOf2(T x) { |
| 39 | return (x & (x - 1)) == 0; |
| 40 | } |
| 41 | |
| 42 | |
| 43 | // Returns smallest power of 2 greater or equal to x (from Hacker's Delight). |
| 44 | int32_t NextPowerOf2(uint32_t x); |
| 45 | |
| 46 | |
| 47 | // The C++ standard leaves the semantics of '>>' |
| 48 | // undefined for negative signed operands. Most |
| 49 | // implementations do the right thing, though. |
| 50 | static inline int ArithmeticShiftRight(int x, int s) { |
| 51 | return x >> s; |
| 52 | } |
| 53 | |
| 54 | |
| 55 | // Compute the 0-relative offset of some absolute value x of type T. |
| 56 | // This allows conversion of Addresses and integral types into 0-relative |
| 57 | // int offsets. |
| 58 | template <typename T> |
| 59 | static inline int OffsetFrom(T x) { |
| 60 | return x - static_cast<T>(0); |
| 61 | } |
| 62 | |
| 63 | |
| 64 | // Compute the absolute value of type T for some 0-relative offset x. |
| 65 | // This allows conversion of 0-relative int offsets into Addresses |
| 66 | // and integral types. |
| 67 | template <typename T> |
| 68 | static inline T AddressFrom(int x) { |
| 69 | return static_cast<T>(0) + x; |
| 70 | } |
| 71 | |
| 72 | |
| 73 | // Return the largest multiple of m which is <= x. |
| 74 | template <typename T> |
| 75 | static inline T RoundDown(T x, int m) { |
| 76 | ASSERT(IsPowerOf2(m)); |
| 77 | return AddressFrom<T>(OffsetFrom(x) & -m); |
| 78 | } |
| 79 | |
| 80 | |
| 81 | // Return the smallest multiple of m which is >= x. |
| 82 | template <typename T> |
| 83 | static inline T RoundUp(T x, int m) { |
| 84 | return RoundDown(x + m - 1, m); |
| 85 | } |
| 86 | |
| 87 | |
| 88 | template <typename T> |
| 89 | static inline bool IsAligned(T value, T alignment) { |
| 90 | ASSERT(IsPowerOf2(alignment)); |
| 91 | return (value & (alignment - 1)) == 0; |
| 92 | } |
| 93 | |
| 94 | |
| 95 | // Returns true if (addr + offset) is aligned. |
| 96 | static inline bool IsAddressAligned(Address addr, int alignment, int offset) { |
| 97 | int offs = OffsetFrom(addr + offset); |
| 98 | return IsAligned(offs, alignment); |
| 99 | } |
| 100 | |
| 101 | |
| 102 | // Returns the maximum of the two parameters. |
| 103 | template <typename T> |
| 104 | static T Max(T a, T b) { |
| 105 | return a < b ? b : a; |
| 106 | } |
| 107 | |
| 108 | |
| 109 | // Returns the minimum of the two parameters. |
| 110 | template <typename T> |
| 111 | static T Min(T a, T b) { |
| 112 | return a < b ? a : b; |
| 113 | } |
| 114 | |
| 115 | |
| 116 | // ---------------------------------------------------------------------------- |
| 117 | // BitField is a help template for encoding and decode bitfield with unsigned |
| 118 | // content. |
| 119 | template<class T, int shift, int size> |
| 120 | class BitField { |
| 121 | public: |
| 122 | // Tells whether the provided value fits into the bit field. |
| 123 | static bool is_valid(T value) { |
| 124 | return (static_cast<uint32_t>(value) & ~((1U << (size)) - 1)) == 0; |
| 125 | } |
| 126 | |
| 127 | // Returns a uint32_t mask of bit field. |
| 128 | static uint32_t mask() { |
| 129 | return (1U << (size + shift)) - (1U << shift); |
| 130 | } |
| 131 | |
| 132 | // Returns a uint32_t with the bit field value encoded. |
| 133 | static uint32_t encode(T value) { |
| 134 | ASSERT(is_valid(value)); |
| 135 | return static_cast<uint32_t>(value) << shift; |
| 136 | } |
| 137 | |
| 138 | // Extracts the bit field from the value. |
| 139 | static T decode(uint32_t value) { |
| 140 | return static_cast<T>((value >> shift) & ((1U << (size)) - 1)); |
| 141 | } |
| 142 | }; |
| 143 | |
| 144 | |
| 145 | // ---------------------------------------------------------------------------- |
| 146 | // Support for compressed, machine-independent encoding |
| 147 | // and decoding of integer values of arbitrary size. |
| 148 | |
| 149 | // Encoding and decoding from/to a buffer at position p; |
| 150 | // the result is the position after the encoded integer. |
| 151 | // Small signed integers in the range -64 <= x && x < 64 |
| 152 | // are encoded in 1 byte; larger values are encoded in 2 |
| 153 | // or more bytes. At most sizeof(int) + 1 bytes are used |
| 154 | // in the worst case. |
| 155 | byte* EncodeInt(byte* p, int x); |
| 156 | byte* DecodeInt(byte* p, int* x); |
| 157 | |
| 158 | |
| 159 | // Encoding and decoding from/to a buffer at position p - 1 |
| 160 | // moving backward; the result is the position of the last |
| 161 | // byte written. These routines are useful to read/write |
| 162 | // into a buffer starting at the end of the buffer. |
| 163 | byte* EncodeUnsignedIntBackward(byte* p, unsigned int x); |
| 164 | |
| 165 | // The decoding function is inlined since its performance is |
| 166 | // important to mark-sweep garbage collection. |
| 167 | inline byte* DecodeUnsignedIntBackward(byte* p, unsigned int* x) { |
| 168 | byte b = *--p; |
| 169 | if (b >= 128) { |
| 170 | *x = static_cast<unsigned int>(b) - 128; |
| 171 | return p; |
| 172 | } |
| 173 | unsigned int r = static_cast<unsigned int>(b); |
| 174 | unsigned int s = 7; |
| 175 | b = *--p; |
| 176 | while (b < 128) { |
| 177 | r |= static_cast<unsigned int>(b) << s; |
| 178 | s += 7; |
| 179 | b = *--p; |
| 180 | } |
| 181 | // b >= 128 |
| 182 | *x = r | ((static_cast<unsigned int>(b) - 128) << s); |
| 183 | return p; |
| 184 | } |
| 185 | |
| 186 | |
| 187 | // ---------------------------------------------------------------------------- |
| 188 | // I/O support. |
| 189 | |
| 190 | // Our version of printf(). Avoids compilation errors that we get |
| 191 | // with standard printf when attempting to print pointers, etc. |
| 192 | // (the errors are due to the extra compilation flags, which we |
| 193 | // want elsewhere). |
| 194 | void PrintF(const char* format, ...); |
| 195 | |
| 196 | // Our version of fflush. |
| 197 | void Flush(); |
| 198 | |
| 199 | |
| 200 | // Read a line of characters after printing the prompt to stdout. The resulting |
| 201 | // char* needs to be disposed off with DeleteArray by the caller. |
| 202 | char* ReadLine(const char* prompt); |
| 203 | |
| 204 | |
| 205 | // Read and return the raw chars in a file. the size of the buffer is returned |
| 206 | // in size. |
| 207 | // The returned buffer is not 0-terminated. It must be freed by the caller. |
| 208 | char* ReadChars(const char* filename, int* size, bool verbose = true); |
| 209 | |
| 210 | |
| 211 | // Write size chars from str to the file given by filename. |
| 212 | // The file is overwritten. Returns the number of chars written. |
| 213 | int WriteChars(const char* filename, |
| 214 | const char* str, |
| 215 | int size, |
| 216 | bool verbose = true); |
| 217 | |
| 218 | |
| 219 | // Write the C code |
| 220 | // const char* <varname> = "<str>"; |
| 221 | // const int <varname>_len = <len>; |
| 222 | // to the file given by filename. Only the first len chars are written. |
| 223 | int WriteAsCFile(const char* filename, const char* varname, |
| 224 | const char* str, int size, bool verbose = true); |
| 225 | |
| 226 | |
| 227 | // ---------------------------------------------------------------------------- |
| 228 | // Miscellaneous |
| 229 | |
| 230 | // A static resource holds a static instance that can be reserved in |
| 231 | // a local scope using an instance of Access. Attempts to re-reserve |
| 232 | // the instance will cause an error. |
| 233 | template <typename T> |
| 234 | class StaticResource { |
| 235 | public: |
| 236 | StaticResource() : is_reserved_(false) {} |
| 237 | |
| 238 | private: |
| 239 | template <typename S> friend class Access; |
| 240 | T instance_; |
| 241 | bool is_reserved_; |
| 242 | }; |
| 243 | |
| 244 | |
| 245 | // Locally scoped access to a static resource. |
| 246 | template <typename T> |
| 247 | class Access { |
| 248 | public: |
| 249 | explicit Access(StaticResource<T>* resource) |
| 250 | : resource_(resource) |
| 251 | , instance_(&resource->instance_) { |
| 252 | ASSERT(!resource->is_reserved_); |
| 253 | resource->is_reserved_ = true; |
| 254 | } |
| 255 | |
| 256 | ~Access() { |
| 257 | resource_->is_reserved_ = false; |
| 258 | resource_ = NULL; |
| 259 | instance_ = NULL; |
| 260 | } |
| 261 | |
| 262 | T* value() { return instance_; } |
| 263 | T* operator -> () { return instance_; } |
| 264 | |
| 265 | private: |
| 266 | StaticResource<T>* resource_; |
| 267 | T* instance_; |
| 268 | }; |
| 269 | |
| 270 | |
| 271 | template <typename T> |
| 272 | class Vector { |
| 273 | public: |
| 274 | Vector(T* data, int length) : start_(data), length_(length) { |
| 275 | ASSERT(length == 0 || (length > 0 && data != NULL)); |
| 276 | } |
| 277 | |
| 278 | // Returns the length of the vector. |
| 279 | int length() const { return length_; } |
| 280 | |
| 281 | // Returns whether or not the vector is empty. |
| 282 | bool is_empty() const { return length_ == 0; } |
| 283 | |
| 284 | // Returns the pointer to the start of the data in the vector. |
| 285 | T* start() const { return start_; } |
| 286 | |
| 287 | // Access individual vector elements - checks bounds in debug mode. |
| 288 | T& operator[](int index) const { |
| 289 | ASSERT(0 <= index && index < length_); |
| 290 | return start_[index]; |
| 291 | } |
| 292 | |
| 293 | // Returns a clone of this vector with a new backing store. |
| 294 | Vector<T> Clone() const { |
| 295 | T* result = NewArray<T>(length_); |
| 296 | for (int i = 0; i < length_; i++) result[i] = start_[i]; |
| 297 | return Vector<T>(result, length_); |
| 298 | } |
| 299 | |
| 300 | // Releases the array underlying this vector. Once disposed the |
| 301 | // vector is empty. |
| 302 | void Dispose() { |
| 303 | DeleteArray(start_); |
| 304 | start_ = NULL; |
| 305 | length_ = 0; |
| 306 | } |
| 307 | |
| 308 | // Factory method for creating empty vectors. |
| 309 | static Vector<T> empty() { return Vector<T>(NULL, 0); } |
| 310 | |
| 311 | private: |
| 312 | T* start_; |
| 313 | int length_; |
| 314 | }; |
| 315 | |
| 316 | |
| 317 | inline Vector<const char> CStrVector(const char* data) { |
| 318 | return Vector<const char>(data, strlen(data)); |
| 319 | } |
| 320 | |
| 321 | inline Vector<char> MutableCStrVector(char* data) { |
| 322 | return Vector<char>(data, strlen(data)); |
| 323 | } |
| 324 | |
| 325 | template <typename T> |
| 326 | inline Vector< Handle<Object> > HandleVector(v8::internal::Handle<T>* elms, |
| 327 | int length) { |
| 328 | return Vector< Handle<Object> >( |
| 329 | reinterpret_cast<v8::internal::Handle<Object>*>(elms), length); |
| 330 | } |
| 331 | |
| 332 | |
| 333 | // Simple support to read a file into a 0-terminated C-string. |
| 334 | // The returned buffer must be freed by the caller. |
| 335 | // On return, *exits tells whether the file exisited. |
| 336 | Vector<const char> ReadFile(const char* filename, |
| 337 | bool* exists, |
| 338 | bool verbose = true); |
| 339 | |
| 340 | |
| 341 | // Simple wrapper that allows an ExternalString to refer to a |
| 342 | // Vector<const char>. Doesn't assume ownership of the data. |
| 343 | class AsciiStringAdapter: public v8::String::ExternalAsciiStringResource { |
| 344 | public: |
| 345 | explicit AsciiStringAdapter(Vector<const char> data) : data_(data) {} |
| 346 | |
| 347 | virtual const char* data() const { return data_.start(); } |
| 348 | |
| 349 | virtual size_t length() const { return data_.length(); } |
| 350 | |
| 351 | private: |
| 352 | Vector<const char> data_; |
| 353 | }; |
| 354 | |
| 355 | |
| 356 | } } // namespace v8::internal |
| 357 | |
| 358 | #endif // V8_UTILS_H_ |