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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /mfbt/double-conversion/utils.h
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Add m-esr52 at 52.6.0
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+// 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__) || defined(__aarch64__)
+#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 len) : start_(data), length_(len) {
+ ASSERT(len == 0 || (len > 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 buffer_size)
+ : buffer_(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_