The Tor Browser: comparison mfbt/double-conversion/utils.h

--1:000000000000
+:1b050e49494b
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#ifndef DOUBLE_CONVERSION_UTILS_H_
+#define DOUBLE_CONVERSION_UTILS_H_
+#include <stdlib.h>
+#include <string.h>
+#include "mozilla/Assertions.h"
+#ifndef ASSERT
+#define ASSERT(condition)      MOZ_ASSERT(condition)
+#endif
+#ifndef UNIMPLEMENTED
+#define UNIMPLEMENTED() MOZ_CRASH()
+#endif
+#ifndef UNREACHABLE
+#define UNREACHABLE()   MOZ_CRASH()
+#endif
+// Double operations detection based on target architecture.
+// Linux uses a 80bit wide floating point stack on x86. This induces double
+// rounding, which in turn leads to wrong results.
+// An easy way to test if the floating-point operations are correct is to
+// evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
+// the result is equal to 89255e-22.
+// The best way to test this, is to create a division-function and to compare
+// the output of the division with the expected result. (Inlining must be
+// disabled.)
+// On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
+#if defined(_M_X64) || defined(__x86_64__) || \
+defined(__ARMEL__) || defined(__avr32__) || \
+defined(__hppa__) || defined(__ia64__) || \
+defined(__mips__) || \
+defined(__powerpc__) || defined(__ppc__) || defined(__ppc64__) || \
+defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
+defined(__SH4__) || defined(__alpha__) || \
+defined(_MIPS_ARCH_MIPS32R2) || \
+defined(__AARCH64EL__)
+#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
+#if defined(_WIN32)
+// Windows uses a 64bit wide floating point stack.
+#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+#else
+#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
+#endif  // _WIN32
+#else
+#error Target architecture was not detected as supported by Double-Conversion.
+#endif
+#include <stdint.h>
+// The following macro works on both 32 and 64-bit platforms.
+// Usage: instead of writing 0x1234567890123456
+//      write UINT64_2PART_C(0x12345678,90123456);
+#define UINT64_2PART_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
+// The expression ARRAY_SIZE(a) is a compile-time constant of type
+// size_t which represents the number of elements of the given
+// array. You should only use ARRAY_SIZE on statically allocated
+// arrays.
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(a)                                   \
+((sizeof(a) / sizeof(*(a))) /                         \
+static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
+#endif
+// A macro to disallow the evil copy constructor and operator= functions
+// This should be used in the private: declarations for a class
+#ifndef DISALLOW_COPY_AND_ASSIGN
+#define DISALLOW_COPY_AND_ASSIGN(TypeName)      \
+TypeName(const TypeName&);                    \
+void operator=(const TypeName&)
+#endif
+// A macro to disallow all the implicit constructors, namely the
+// default constructor, copy constructor and operator= functions.
+//
+// This should be used in the private: declarations for a class
+// that wants to prevent anyone from instantiating it. This is
+// especially useful for classes containing only static methods.
+#ifndef DISALLOW_IMPLICIT_CONSTRUCTORS
+#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
+TypeName();                                    \
+DISALLOW_COPY_AND_ASSIGN(TypeName)
+#endif
+namespace double_conversion {
+static const int kCharSize = sizeof(char);
+// Returns the maximum of the two parameters.
+template <typename T>
+static T Max(T a, T b) {
+return a < b ? b : a;
+}
+// Returns the minimum of the two parameters.
+template <typename T>
+static T Min(T a, T b) {
+return a < b ? a : b;
+}
+inline int StrLength(const char* string) {
+size_t length = strlen(string);
+ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
+return static_cast<int>(length);
+}
+// This is a simplified version of V8's Vector class.
+template <typename T>
+class Vector {
+public:
+Vector() : start_(NULL), length_(0) {}
+Vector(T* data, int length) : start_(data), length_(length) {
+ASSERT(length == 0 || (length > 0 && data != NULL));
+}
+// Returns a vector using the same backing storage as this one,
+// spanning from and including 'from', to but not including 'to'.
+Vector<T> SubVector(int from, int to) {
+ASSERT(to <= length_);
+ASSERT(from < to);
+ASSERT(0 <= from);
+return Vector<T>(start() + from, to - from);
+}
+// Returns the length of the vector.
+int length() const { return length_; }
+// Returns whether or not the vector is empty.
+bool is_empty() const { return length_ == 0; }
+// Returns the pointer to the start of the data in the vector.
+T* start() const { return start_; }
+// Access individual vector elements - checks bounds in debug mode.
+T& operator[](int index) const {
+ASSERT(0 <= index && index < length_);
+return start_[index];
+}
+T& first() { return start_[0]; }
+T& last() { return start_[length_ - 1]; }
+private:
+T* start_;
+int length_;
+};
+// Helper class for building result strings in a character buffer. The
+// purpose of the class is to use safe operations that checks the
+// buffer bounds on all operations in debug mode.
+class StringBuilder {
+public:
+StringBuilder(char* buffer, int size)
+: buffer_(buffer, size), position_(0) { }
+~StringBuilder() { if (!is_finalized()) Finalize(); }
+int size() const { return buffer_.length(); }
+// Get the current position in the builder.
+int position() const {
+ASSERT(!is_finalized());
+return position_;
+}
+// Reset the position.
+void Reset() { position_ = 0; }
+// Add a single character to the builder. It is not allowed to add
+// 0-characters; use the Finalize() method to terminate the string
+// instead.
+void AddCharacter(char c) {
+ASSERT(c != '\0');
+ASSERT(!is_finalized() && position_ < buffer_.length());
+buffer_[position_++] = c;
+}
+// Add an entire string to the builder. Uses strlen() internally to
+// compute the length of the input string.
+void AddString(const char* s) {
+AddSubstring(s, StrLength(s));
+}
+// Add the first 'n' characters of the given string 's' to the
+// builder. The input string must have enough characters.
+void AddSubstring(const char* s, int n) {
+ASSERT(!is_finalized() && position_ + n < buffer_.length());
+ASSERT(static_cast<size_t>(n) <= strlen(s));
+memmove(&buffer_[position_], s, n * kCharSize);
+position_ += n;
+}
+// Add character padding to the builder. If count is non-positive,
+// nothing is added to the builder.
+void AddPadding(char c, int count) {
+for (int i = 0; i < count; i++) {
+AddCharacter(c);
+}
+}
+// Finalize the string by 0-terminating it and returning the buffer.
+char* Finalize() {
+ASSERT(!is_finalized() && position_ < buffer_.length());
+buffer_[position_] = '\0';
+// Make sure nobody managed to add a 0-character to the
+// buffer while building the string.
+ASSERT(strlen(buffer_.start()) == static_cast<size_t>(position_));
+position_ = -1;
+ASSERT(is_finalized());
+return buffer_.start();
+}
+private:
+Vector<char> buffer_;
+int position_;
+bool is_finalized() const { return position_ < 0; }
+DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
+};
+// The type-based aliasing rule allows the compiler to assume that pointers of
+// different types (for some definition of different) never alias each other.
+// Thus the following code does not work:
+//
+// float f = foo();
+// int fbits = *(int*)(&f);
+//
+// The compiler 'knows' that the int pointer can't refer to f since the types
+// don't match, so the compiler may cache f in a register, leaving random data
+// in fbits.  Using C++ style casts makes no difference, however a pointer to
+// char data is assumed to alias any other pointer.  This is the 'memcpy
+// exception'.
+//
+// Bit_cast uses the memcpy exception to move the bits from a variable of one
+// type of a variable of another type.  Of course the end result is likely to
+// be implementation dependent.  Most compilers (gcc-4.2 and MSVC 2005)
+// will completely optimize BitCast away.
+//
+// There is an additional use for BitCast.
+// Recent gccs will warn when they see casts that may result in breakage due to
+// the type-based aliasing rule.  If you have checked that there is no breakage
+// you can use BitCast to cast one pointer type to another.  This confuses gcc
+// enough that it can no longer see that you have cast one pointer type to
+// another thus avoiding the warning.
+template <class Dest, class Source>
+inline Dest BitCast(const Source& source) {
+static_assert(sizeof(Dest) == sizeof(Source),
+"BitCast's source and destination types must be the same size");
+Dest dest;
+memmove(&dest, &source, sizeof(dest));
+return dest;
+}
+template <class Dest, class Source>
+inline Dest BitCast(Source* source) {
+return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
+}
+}  // namespace double_conversion
+#endif  // DOUBLE_CONVERSION_UTILS_H_

The Tor Browser / file comparison

comparison: mfbt/double-conversion/utils.h

mfbt/double-conversion/utils.h