1 // Copyright 2010 the V8 project authors. 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
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.
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
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20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #ifndef DOUBLE_CONVERSION_UTILS_H_
29 #define DOUBLE_CONVERSION_UTILS_H_
31 #include "wtf/Assertions.h"
34 #define UNIMPLEMENTED ASSERT_NOT_REACHED
35 #define UNREACHABLE ASSERT_NOT_REACHED
37 // Double operations detection based on target architecture.
38 // Linux uses a 80bit wide floating point stack on x86. This induces double
39 // rounding, which in turn leads to wrong results.
40 // An easy way to test if the floating-point operations are correct is to
41 // evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
42 // the result is equal to 89255e-22.
43 // The best way to test this, is to create a division-function and to compare
44 // the output of the division with the expected result. (Inlining must be
46 // On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
47 #if defined(_M_X64) || defined(__x86_64__) || \
48 defined(__ARMEL__) || defined(__aarch64__) || \
50 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
51 #elif defined(_M_IX86) || defined(__i386__)
53 // Windows uses a 64bit wide floating point stack.
54 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
56 #undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
59 #error Target architecture was not detected as supported by Double-Conversion.
63 #if defined(_WIN32) && !defined(__MINGW32__)
65 typedef signed char int8_t;
66 typedef unsigned char uint8_t;
67 typedef short int16_t; // NOLINT
68 typedef unsigned short uint16_t; // NOLINT
70 typedef unsigned int uint32_t;
71 typedef __int64 int64_t;
72 typedef unsigned __int64 uint64_t;
73 // intptr_t and friends are defined in crtdefs.h through stdio.h.
81 // The following macro works on both 32 and 64-bit platforms.
82 // Usage: instead of writing 0x1234567890123456
83 // write UINT64_2PART_C(0x12345678,90123456);
84 #define UINT64_2PART_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
87 // The expression ARRAY_SIZE(a) is a compile-time constant of type
88 // size_t which represents the number of elements of the given
89 // array. You should only use ARRAY_SIZE on statically allocated
91 #define ARRAY_SIZE(a) \
92 ((sizeof(a) / sizeof(*(a))) / \
93 static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
95 // A macro to disallow the evil copy constructor and operator= functions
96 // This should be used in the private: declarations for a class
97 #define DISALLOW_COPY_AND_ASSIGN(TypeName) \
98 TypeName(const TypeName&); \
99 void operator=(const TypeName&)
101 // A macro to disallow all the implicit constructors, namely the
102 // default constructor, copy constructor and operator= functions.
104 // This should be used in the private: declarations for a class
105 // that wants to prevent anyone from instantiating it. This is
106 // especially useful for classes containing only static methods.
107 #define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
109 DISALLOW_COPY_AND_ASSIGN(TypeName)
113 namespace double_conversion {
115 static const int kCharSize = sizeof(char);
117 // Returns the maximum of the two parameters.
118 template <typename T>
119 static T Max(T a, T b) {
120 return a < b ? b : a;
124 // Returns the minimum of the two parameters.
125 template <typename T>
126 static T Min(T a, T b) {
127 return a < b ? a : b;
131 inline int StrLength(const char* string) {
132 size_t length = strlen(string);
133 ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
134 return static_cast<int>(length);
137 // This is a simplified version of V8's Vector class.
138 template <typename T>
141 Vector() : start_(NULL), length_(0) {}
142 Vector(T* data, int length) : start_(data), length_(length) {
143 ASSERT(length == 0 || (length > 0 && data != NULL));
146 // Returns a vector using the same backing storage as this one,
147 // spanning from and including 'from', to but not including 'to'.
148 Vector<T> SubVector(int from, int to) {
149 ASSERT(to <= length_);
152 return Vector<T>(start() + from, to - from);
155 // Returns the length of the vector.
156 int length() const { return length_; }
158 // Returns whether or not the vector is empty.
159 bool is_empty() const { return length_ == 0; }
161 // Returns the pointer to the start of the data in the vector.
162 T* start() const { return start_; }
164 // Access individual vector elements - checks bounds in debug mode.
165 T& operator[](int index) const {
166 ASSERT(0 <= index && index < length_);
167 return start_[index];
170 T& first() { return start_[0]; }
172 T& last() { return start_[length_ - 1]; }
180 // Helper class for building result strings in a character buffer. The
181 // purpose of the class is to use safe operations that checks the
182 // buffer bounds on all operations in debug mode.
183 class StringBuilder {
185 StringBuilder(char* buffer, int size)
186 : buffer_(buffer, size), position_(0) { }
188 ~StringBuilder() { if (!is_finalized()) Finalize(); }
190 int size() const { return buffer_.length(); }
192 // Get the current position in the builder.
193 int position() const {
194 ASSERT(!is_finalized());
198 // Set the current position in the builder.
199 void SetPosition(int position)
201 ASSERT(!is_finalized());
202 ASSERT_WITH_SECURITY_IMPLICATION(position < size());
203 position_ = position;
206 // Reset the position.
207 void Reset() { position_ = 0; }
209 // Add a single character to the builder. It is not allowed to add
210 // 0-characters; use the Finalize() method to terminate the string
212 void AddCharacter(char c) {
214 ASSERT(!is_finalized() && position_ < buffer_.length());
215 buffer_[position_++] = c;
218 // Add an entire string to the builder. Uses strlen() internally to
219 // compute the length of the input string.
220 void AddString(const char* s) {
221 AddSubstring(s, StrLength(s));
224 // Add the first 'n' characters of the given string 's' to the
225 // builder. The input string must have enough characters.
226 void AddSubstring(const char* s, int n) {
227 ASSERT(!is_finalized() && position_ + n < buffer_.length());
228 ASSERT_WITH_SECURITY_IMPLICATION(static_cast<size_t>(n) <= strlen(s));
229 memcpy(&buffer_[position_], s, n * kCharSize);
234 // Add character padding to the builder. If count is non-positive,
235 // nothing is added to the builder.
236 void AddPadding(char c, int count) {
237 for (int i = 0; i < count; i++) {
242 // Finalize the string by 0-terminating it and returning the buffer.
244 ASSERT(!is_finalized() && position_ < buffer_.length());
245 buffer_[position_] = '\0';
246 // Make sure nobody managed to add a 0-character to the
247 // buffer while building the string.
248 ASSERT(strlen(buffer_.start()) == static_cast<size_t>(position_));
250 ASSERT(is_finalized());
251 return buffer_.start();
255 Vector<char> buffer_;
258 bool is_finalized() const { return position_ < 0; }
260 DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
263 // The type-based aliasing rule allows the compiler to assume that pointers of
264 // different types (for some definition of different) never alias each other.
265 // Thus the following code does not work:
268 // int fbits = *(int*)(&f);
270 // The compiler 'knows' that the int pointer can't refer to f since the types
271 // don't match, so the compiler may cache f in a register, leaving random data
272 // in fbits. Using C++ style casts makes no difference, however a pointer to
273 // char data is assumed to alias any other pointer. This is the 'memcpy
276 // Bit_cast uses the memcpy exception to move the bits from a variable of one
277 // type of a variable of another type. Of course the end result is likely to
278 // be implementation dependent. Most compilers (gcc-4.2 and MSVC 2005)
279 // will completely optimize BitCast away.
281 // There is an additional use for BitCast.
282 // Recent gccs will warn when they see casts that may result in breakage due to
283 // the type-based aliasing rule. If you have checked that there is no breakage
284 // you can use BitCast to cast one pointer type to another. This confuses gcc
285 // enough that it can no longer see that you have cast one pointer type to
286 // another thus avoiding the warning.
287 template <class Dest, class Source>
288 inline Dest BitCast(const Source& source) {
289 // Compile time assertion: sizeof(Dest) == sizeof(Source)
290 // A compile error here means your Dest and Source have different sizes.
291 typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];
294 memcpy(&dest, &source, sizeof(dest));
298 template <class Dest, class Source>
299 inline Dest BitCast(Source* source) {
300 return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
303 } // namespace double_conversion
307 #endif // DOUBLE_CONVERSION_UTILS_H_