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
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 DOUBLE_CONVERSION_UTILS_H_
29#define DOUBLE_CONVERSION_UTILS_H_
30
31#include <stdlib.h>
32#include <string.h>
33
34#include <assert.h>
35#ifndef ASSERT
36#define ASSERT(condition) \
37 assert(condition);
38#endif
39#ifndef UNIMPLEMENTED
40#define UNIMPLEMENTED() (abort())
41#endif
42#ifndef UNREACHABLE
43#define UNREACHABLE() (abort())
44#endif
45
46// Double operations detection based on target architecture.
47// Linux uses a 80bit wide floating point stack on x86. This induces double
48// rounding, which in turn leads to wrong results.
49// An easy way to test if the floating-point operations are correct is to
50// evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
51// the result is equal to 89255e-22.
52// The best way to test this, is to create a division-function and to compare
53// the output of the division with the expected result. (Inlining must be
54// disabled.)
55// On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
56#if defined(_M_X64) || defined(__x86_64__) || \
57 defined(__ARMEL__) || defined(__avr32__) || \
58 defined(__hppa__) || defined(__ia64__) || \
59 defined(__mips__) || \
60 defined(__powerpc__) || defined(__ppc__) || defined(__ppc64__) || \
61 defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
62 defined(__SH4__) || defined(__alpha__) || \
63 defined(_MIPS_ARCH_MIPS32R2) || \
64 defined(__AARCH64EL__)
65#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
66#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
67#if defined(_WIN32)
68// Windows uses a 64bit wide floating point stack.
69#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
70#else
71#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
72#endif // _WIN32
73#elif defined(__m68k__)
74// The MC68881 also uses an 80bit wide floating point stack.
75#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
76#else
77#error Target architecture was not detected as supported by Double-Conversion.
78#endif
79
80#if defined(__GNUC__)
81#define DOUBLE_CONVERSION_UNUSED __attribute__((unused))
82#else
83#define DOUBLE_CONVERSION_UNUSED
84#endif
85
86#if defined(_WIN32) && !defined(__MINGW32__)
87
88typedef signed char int8_t;
89typedef unsigned char uint8_t;
90typedef short int16_t; // NOLINT
91typedef unsigned short uint16_t; // NOLINT
92typedef int int32_t;
93typedef unsigned int uint32_t;
94typedef __int64 int64_t;
95typedef unsigned __int64 uint64_t;
96// intptr_t and friends are defined in crtdefs.h through stdio.h.
97
98#else
99
100#include <stdint.h>
101
102#endif
103
104typedef uint16_t uc16;
105
106// The following macro works on both 32 and 64-bit platforms.
107// Usage: instead of writing 0x1234567890123456
108// write UINT64_2PART_C(0x12345678,90123456);
109#define UINT64_2PART_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
110
111
112// The expression ARRAY_SIZE(a) is a compile-time constant of type
113// size_t which represents the number of elements of the given
114// array. You should only use ARRAY_SIZE on statically allocated
115// arrays.
116#ifndef ARRAY_SIZE
117#define ARRAY_SIZE(a) \
118 ((sizeof(a) / sizeof(*(a))) / \
119 static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
120#endif
121
122// A macro to disallow the evil copy constructor and operator= functions
123// This should be used in the private: declarations for a class
124#ifndef DISALLOW_COPY_AND_ASSIGN
125#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
126 TypeName(const TypeName&); \
127 void operator=(const TypeName&)
128#endif
129
130// A macro to disallow all the implicit constructors, namely the
131// default constructor, copy constructor and operator= functions.
132//
133// This should be used in the private: declarations for a class
134// that wants to prevent anyone from instantiating it. This is
135// especially useful for classes containing only static methods.
136#ifndef DISALLOW_IMPLICIT_CONSTRUCTORS
137#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
138 TypeName(); \
139 DISALLOW_COPY_AND_ASSIGN(TypeName)
140#endif
141
142namespace double_conversion {
143
144static const int kCharSize = sizeof(char);
145
146// Returns the maximum of the two parameters.
147template <typename T>
148static T Max(T a, T b) {
149 return a < b ? b : a;
150}
151
152
153// Returns the minimum of the two parameters.
154template <typename T>
155static T Min(T a, T b) {
156 return a < b ? a : b;
157}
158
159
160inline int StrLength(const char* string) {
161 size_t length = strlen(string);
162 ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
163 return static_cast<int>(length);
164}
165
166// This is a simplified version of V8's Vector class.
167template <typename T>
168class Vector {
169 public:
170 Vector() : start_(NULL), length_(0) {}
171 Vector(T* data, int length) : start_(data), length_(length) {
172 ASSERT(length == 0 || (length > 0 && data != NULL));
173 }
174
175 // Returns a vector using the same backing storage as this one,
176 // spanning from and including 'from', to but not including 'to'.
177 Vector<T> SubVector(int from, int to) {
178 ASSERT(to <= length_);
179 ASSERT(from < to);
180 ASSERT(0 <= from);
181 return Vector<T>(start() + from, to - from);
182 }
183
184 // Returns the length of the vector.
185 int length() const { return length_; }
186
187 // Returns whether or not the vector is empty.
188 bool is_empty() const { return length_ == 0; }
189
190 // Returns the pointer to the start of the data in the vector.
191 T* start() const { return start_; }
192
193 // Access individual vector elements - checks bounds in debug mode.
194 T& operator[](int index) const {
195 ASSERT(0 <= index && index < length_);
196 return start_[index];
197 }
198
199 T& first() { return start_[0]; }
200
201 T& last() { return start_[length_ - 1]; }
202
203 private:
204 T* start_;
205 int length_;
206};
207
208
209// Helper class for building result strings in a character buffer. The
210// purpose of the class is to use safe operations that checks the
211// buffer bounds on all operations in debug mode.
212class StringBuilder {
213 public:
214 StringBuilder(char* buffer, int size)
215 : buffer_(buffer, size), position_(0) { }
216
217 ~StringBuilder() { if (!is_finalized()) Finalize(); }
218
219 int size() const { return buffer_.length(); }
220
221 // Get the current position in the builder.
222 int position() const {
223 ASSERT(!is_finalized());
224 return position_;
225 }
226
227 // Reset the position.
228 void Reset() { position_ = 0; }
229
230 // Add a single character to the builder. It is not allowed to add
231 // 0-characters; use the Finalize() method to terminate the string
232 // instead.
233 void AddCharacter(char c) {
234 ASSERT(c != '\0');
235 ASSERT(!is_finalized() && position_ < buffer_.length());
236 buffer_[position_++] = c;
237 }
238
239 // Add an entire string to the builder. Uses strlen() internally to
240 // compute the length of the input string.
241 void AddString(const char* s) {
242 AddSubstring(s, StrLength(s));
243 }
244
245 // Add the first 'n' characters of the given string 's' to the
246 // builder. The input string must have enough characters.
247 void AddSubstring(const char* s, int n) {
248 ASSERT(!is_finalized() && position_ + n < buffer_.length());
249 ASSERT(static_cast<size_t>(n) <= strlen(s));
250 memmove(&buffer_[position_], s, n * kCharSize);
251 position_ += n;
252 }
253
254
255 // Add character padding to the builder. If count is non-positive,
256 // nothing is added to the builder.
257 void AddPadding(char c, int count) {
258 for (int i = 0; i < count; i++) {
259 AddCharacter(c);
260 }
261 }
262
263 // Finalize the string by 0-terminating it and returning the buffer.
264 char* Finalize() {
265 ASSERT(!is_finalized() && position_ < buffer_.length());
266 buffer_[position_] = '\0';
267 // Make sure nobody managed to add a 0-character to the
268 // buffer while building the string.
269 ASSERT(strlen(buffer_.start()) == static_cast<size_t>(position_));
270 position_ = -1;
271 ASSERT(is_finalized());
272 return buffer_.start();
273 }
274
275 private:
276 Vector<char> buffer_;
277 int position_;
278
279 bool is_finalized() const { return position_ < 0; }
280
281 DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
282};
283
284// The type-based aliasing rule allows the compiler to assume that pointers of
285// different types (for some definition of different) never alias each other.
286// Thus the following code does not work:
287//
288// float f = foo();
289// int fbits = *(int*)(&f);
290//
291// The compiler 'knows' that the int pointer can't refer to f since the types
292// don't match, so the compiler may cache f in a register, leaving random data
293// in fbits. Using C++ style casts makes no difference, however a pointer to
294// char data is assumed to alias any other pointer. This is the 'memcpy
295// exception'.
296//
297// Bit_cast uses the memcpy exception to move the bits from a variable of one
298// type of a variable of another type. Of course the end result is likely to
299// be implementation dependent. Most compilers (gcc-4.2 and MSVC 2005)
300// will completely optimize BitCast away.
301//
302// There is an additional use for BitCast.
303// Recent gccs will warn when they see casts that may result in breakage due to
304// the type-based aliasing rule. If you have checked that there is no breakage
305// you can use BitCast to cast one pointer type to another. This confuses gcc
306// enough that it can no longer see that you have cast one pointer type to
307// another thus avoiding the warning.
308template <class Dest, class Source>
309inline Dest BitCast(const Source& source) {
310 // Compile time assertion: sizeof(Dest) == sizeof(Source)
311 // A compile error here means your Dest and Source have different sizes.
312 DOUBLE_CONVERSION_UNUSED
313 typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];
314
315 Dest dest;
316 memmove(&dest, &source, sizeof(dest));
317 return dest;
318}
319
320template <class Dest, class Source>
321inline Dest BitCast(Source* source) {
322 return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
323}
324
325} // namespace double_conversion
326
327#endif // DOUBLE_CONVERSION_UTILS_H_
328