// 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 <cstdlib>

#include <cstring>

#include "mozilla/Assertions.h"

#ifndef ASSERT

#define ASSERT(condition)         \

    MOZ_ASSERT(condition)

#endif

#ifndef UNIMPLEMENTED

#define UNIMPLEMENTED() MOZ_CRASH()

#endif

#ifndef DOUBLE_CONVERSION_NO_RETURN

#ifdef _MSC_VER

#define DOUBLE_CONVERSION_NO_RETURN __declspec(noreturn)

#else

#define DOUBLE_CONVERSION_NO_RETURN __attribute__((noreturn))

#endif

#endif

#ifndef UNREACHABLE

#ifdef _MSC_VER

void DOUBLE_CONVERSION_NO_RETURN abort_noreturn();

inline void abort_noreturn() { MOZ_CRASH(); }

#define UNREACHABLE()   (abort_noreturn())

#else

#define UNREACHABLE()   MOZ_CRASH()

#endif

#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(_M_ARM) || defined(_M_ARM64) || \

    defined(__hppa__) || defined(__ia64__) || \

    defined(__mips__) || \

    defined(__powerpc__) || defined(__ppc__) || defined(__ppc64__) || \

    defined(_POWER) || defined(_ARCH_PPC) || defined(_ARCH_PPC64) || \

    defined(__sparc__) || defined(__sparc) || defined(__s390__) || \

    defined(__SH4__) || defined(__alpha__) || \

    defined(_MIPS_ARCH_MIPS32R2) || \

    defined(__AARCH64EL__) || defined(__aarch64__) || \

    defined(__riscv)

#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1

#elif defined(__mc68000__) || \

    defined(__pnacl__) || defined(__native_client__)

#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS

#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

#if defined(_WIN32) && !defined(__MINGW32__)

typedef signed char int8_t;

typedef unsigned char uint8_t;

typedef short int16_t;  // NOLINT

typedef unsigned short uint16_t;  // NOLINT

typedef int int32_t;

typedef unsigned int uint32_t;

typedef __int64 int64_t;

typedef unsigned __int64 uint64_t;

// intptr_t and friends are defined in crtdefs.h through stdio.h.

#else

#include <stdint.h>

#endif

typedef uint16_t uc16;

// 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 DC_DISALLOW_COPY_AND_ASSIGN

#define DC_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 DC_DISALLOW_IMPLICIT_CONSTRUCTORS

#define DC_DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \

  TypeName();                                    \

  DC_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; }

  DC_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) {

  // Compile time assertion: sizeof(Dest) == sizeof(Source)

  // A compile error here means your Dest and Source have different sizes.

#if __cplusplus >= 201103L

  static_assert(sizeof(Dest) == sizeof(Source),

                "source and destination size mismatch");

#else

  typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];

#endif

  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_