text: // Copyright 2006-2008 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.
  
  // Platform specific code for Win32.
  #ifndef WIN32_LEAN_AND_MEAN
  // WIN32_LEAN_AND_MEAN implies NOCRYPT and NOGDI.
  #define WIN32_LEAN_AND_MEAN
  #endif
  #ifndef NOMINMAX
  #define NOMINMAX
  #endif
  #ifndef NOKERNEL
  #define NOKERNEL
  #endif
  #ifndef NOUSER
  #define NOUSER
  #endif
  #ifndef NOSERVICE
  #define NOSERVICE
  #endif
  #ifndef NOSOUND
  #define NOSOUND
  #endif
  #ifndef NOMCX
  #define NOMCX
  #endif
  // Require Windows 2000 or higher (this is required for the IsDebuggerPresent
  // function to be present).
  #ifndef _WIN32_WINNT
  #define _WIN32_WINNT 0x500
  #endif
  
  #include <windows.h>
  
  #include <time.h>  // For LocalOffset() implementation.
  #include <mmsystem.h>  // For timeGetTime().
  #ifdef __MINGW32__
  // Require Windows XP or higher when compiling with MinGW. This is for MinGW
  // header files to expose getaddrinfo.
  #undef _WIN32_WINNT
  #define _WIN32_WINNT 0x501
  #endif  // __MINGW32__
  #ifndef __MINGW32__
  #include <dbghelp.h>  // For SymLoadModule64 and al.
  #endif  // __MINGW32__
  #include <limits.h>  // For INT_MAX and al.
  #include <tlhelp32.h>  // For Module32First and al.
  
  // These additional WIN32 includes have to be right here as the #undef's below
  // makes it impossible to have them elsewhere.
  #include <winsock2.h>
  #include <ws2tcpip.h>
  #include <process.h>  // for _beginthreadex()
  #include <stdlib.h>
  
  #undef VOID
  #undef DELETE
  #undef IN
  #undef THIS
  #undef CONST
  #undef NAN
  #undef GetObject
  #undef CreateMutex
  #undef CreateSemaphore
  
  #include "v8.h"
  
  #include "platform.h"
  
  // Extra POSIX/ANSI routines for Win32 when when using Visual Studio C++. Please
  // refer to The Open Group Base Specification for specification of the correct
  // semantics for these functions.
  // (http://www.opengroup.org/onlinepubs/000095399/)
  #ifdef _MSC_VER
  
  namespace v8 {
  namespace internal {
  
  // Test for finite value - usually defined in math.h
  int isfinite(double x) {
    return _finite(x);
  }
  
  }  // namespace v8
  }  // namespace internal
  
  // Test for a NaN (not a number) value - usually defined in math.h
  int isnan(double x) {
    return _isnan(x);
  }
  
  
  // Test for infinity - usually defined in math.h
  int isinf(double x) {
    return (_fpclass(x) & (_FPCLASS_PINF | _FPCLASS_NINF)) != 0;
  }
  
  
  // Test if x is less than y and both nominal - usually defined in math.h
  int isless(double x, double y) {
    return isnan(x) || isnan(y) ? 0 : x < y;
  }
  
  
  // Test if x is greater than y and both nominal - usually defined in math.h
  int isgreater(double x, double y) {
    return isnan(x) || isnan(y) ? 0 : x > y;
  }
  
  
  // Classify floating point number - usually defined in math.h
  int fpclassify(double x) {
    // Use the MS-specific _fpclass() for classification.
    int flags = _fpclass(x);
  
    // Determine class. We cannot use a switch statement because
    // the _FPCLASS_ constants are defined as flags.
    if (flags & (_FPCLASS_PN | _FPCLASS_NN)) return FP_NORMAL;
    if (flags & (_FPCLASS_PZ | _FPCLASS_NZ)) return FP_ZERO;
    if (flags & (_FPCLASS_PD | _FPCLASS_ND)) return FP_SUBNORMAL;
    if (flags & (_FPCLASS_PINF | _FPCLASS_NINF)) return FP_INFINITE;
  
    // All cases should be covered by the code above.
    ASSERT(flags & (_FPCLASS_SNAN | _FPCLASS_QNAN));
    return FP_NAN;
  }
  
  
  // Test sign - usually defined in math.h
  int signbit(double x) {
    // We need to take care of the special case of both positive
    // and negative versions of zero.
    if (x == 0)
      return _fpclass(x) & _FPCLASS_NZ;
    else
      return x < 0;
  }
  
  
  // Case-insensitive bounded string comparisons. Use stricmp() on Win32. Usually
  // defined in strings.h.
  int strncasecmp(const char* s1, const char* s2, int n) {
    return _strnicmp(s1, s2, n);
  }
  
  #endif  // _MSC_VER
  
  
  // Extra functions for MinGW. Most of these are the _s functions which are in
  // the Microsoft Visual Studio C++ CRT.
  #ifdef __MINGW32__
  
  int localtime_s(tm* out_tm, const time_t* time) {
    tm* posix_local_time_struct = localtime(time);
    if (posix_local_time_struct == NULL) return 1;
    *out_tm = *posix_local_time_struct;
    return 0;
  }
  
  
  // Not sure this the correct interpretation of _mkgmtime
  time_t _mkgmtime(tm* timeptr) {
    return mktime(timeptr);
  }
  
  
  int fopen_s(FILE** pFile, const char* filename, const char* mode) {
    *pFile = fopen(filename, mode);
    return *pFile != NULL ? 0 : 1;
  }
  
  
  int _vsnprintf_s(char* buffer, size_t sizeOfBuffer, size_t count,
                   const char* format, va_list argptr) {
    return _vsnprintf(buffer, sizeOfBuffer, format, argptr);
  }
  #define _TRUNCATE 0
  
  
  int strncpy_s(char* strDest, size_t numberOfElements,
                const char* strSource, size_t count) {
    strncpy(strDest, strSource, count);
    return 0;
  }
  
  #endif  // __MINGW32__
  
  // Generate a pseudo-random number in the range 0-2^31-1. Usually
  // defined in stdlib.h. Missing in both Microsoft Visual Studio C++ and MinGW.
  int random() {
    return rand();
  }
  
  
  namespace v8 {
  namespace internal {
  
  double ceiling(double x) {
    return ceil(x);
  }
  
  // ----------------------------------------------------------------------------
  // The Time class represents time on win32. A timestamp is represented as
  // a 64-bit integer in 100 nano-seconds since January 1, 1601 (UTC). JavaScript
  // timestamps are represented as a doubles in milliseconds since 00:00:00 UTC,
  // January 1, 1970.
  
  class Time {
   public:
    // Constructors.
    Time();
    explicit Time(double jstime);
    Time(int year, int mon, int day, int hour, int min, int sec);
  
    // Convert timestamp to JavaScript representation.
    double ToJSTime();
  
    // Set timestamp to current time.
    void SetToCurrentTime();
  
    // Returns the local timezone offset in milliseconds east of UTC. This is
    // the number of milliseconds you must add to UTC to get local time, i.e.
    // LocalOffset(CET) = 3600000 and LocalOffset(PST) = -28800000. This
    // routine also takes into account whether daylight saving is effect
    // at the time.
    int64_t LocalOffset();
  
    // Returns the daylight savings time offset for the time in milliseconds.
    int64_t DaylightSavingsOffset();
  
    // Returns a string identifying the current timezone for the
    // timestamp taking into account daylight saving.
    char* LocalTimezone();
  
   private:
    // Constants for time conversion.
    static const int64_t kTimeEpoc = 116444736000000000LL;
    static const int64_t kTimeScaler = 10000;
    static const int64_t kMsPerMinute = 60000;
  
    // Constants for timezone information.
    static const int kTzNameSize = 128;
    static const bool kShortTzNames = false;
  
    // Timezone information. We need to have static buffers for the
    // timezone names because we return pointers to these in
    // LocalTimezone().
    static bool tz_initialized_;
    static TIME_ZONE_INFORMATION tzinfo_;
    static char std_tz_name_[kTzNameSize];
    static char dst_tz_name_[kTzNameSize];
  
    // Initialize the timezone information (if not already done).
    static void TzSet();
  
    // Guess the name of the timezone from the bias.
    static const char* GuessTimezoneNameFromBias(int bias);
  
    // Return whether or not daylight savings time is in effect at this time.
    bool InDST();
  
    // Return the difference (in milliseconds) between this timestamp and
    // another timestamp.
    int64_t Diff(Time* other);
  
    // Accessor for FILETIME representation.
    FILETIME& ft() { return time_.ft_; }
  
    // Accessor for integer representation.
    int64_t& t() { return time_.t_; }
  
    // Although win32 uses 64-bit integers for representing timestamps,
    // these are packed into a FILETIME structure. The FILETIME structure
    // is just a struct representing a 64-bit integer. The TimeStamp union
    // allows access to both a FILETIME and an integer representation of
    // the timestamp.
    union TimeStamp {
      FILETIME ft_;
      int64_t t_;
    };
  
    TimeStamp time_;
  };
  
  // Static variables.
  bool Time::tz_initialized_ = false;
  TIME_ZONE_INFORMATION Time::tzinfo_;
  char Time::std_tz_name_[kTzNameSize];
  char Time::dst_tz_name_[kTzNameSize];
  
  
  // Initialize timestamp to start of epoc.
  Time::Time() {
    t() = 0;
  }
  
  
  // Initialize timestamp from a JavaScript timestamp.
  Time::Time(double jstime) {
    t() = static_cast<int64_t>(jstime) * kTimeScaler + kTimeEpoc;
  }
  
  
  // Initialize timestamp from date/time components.
  Time::Time(int year, int mon, int day, int hour, int min, int sec) {
    SYSTEMTIME st;
    st.wYear = year;
    st.wMonth = mon;
    st.wDay = day;
    st.wHour = hour;
    st.wMinute = min;
    st.wSecond = sec;
    st.wMilliseconds = 0;
    SystemTimeToFileTime(&st, &ft());
  }
  
  
  // Convert timestamp to JavaScript timestamp.
  double Time::ToJSTime() {
    return static_cast<double>((t() - kTimeEpoc) / kTimeScaler);
  }
  
  
  // Guess the name of the timezone from the bias.
  // The guess is very biased towards the northern hemisphere.
  const char* Time::GuessTimezoneNameFromBias(int bias) {
    static const int kHour = 60;
    switch (-bias) {
      case -9*kHour: return "Alaska";
      case -8*kHour: return "Pacific";
      case -7*kHour: return "Mountain";
      case -6*kHour: return "Central";
      case -5*kHour: return "Eastern";
      case -4*kHour: return "Atlantic";
      case  0*kHour: return "GMT";
      case +1*kHour: return "Central Europe";
      case +2*kHour: return "Eastern Europe";
      case +3*kHour: return "Russia";
      case +5*kHour + 30: return "India";
      case +8*kHour: return "China";
      case +9*kHour: return "Japan";
      case +12*kHour: return "New Zealand";
      default: return "Local";
    }
  }
  
  
  // Initialize timezone information. The timezone information is obtained from
  // windows. If we cannot get the timezone information we fall back to CET.
  // Please notice that this code is not thread-safe.
  void Time::TzSet() {
    // Just return if timezone information has already been initialized.
    if (tz_initialized_) return;
  
    // Initialize POSIX time zone data.
    _tzset();
    // Obtain timezone information from operating system.
    memset(&tzinfo_, 0, sizeof(tzinfo_));
    if (GetTimeZoneInformation(&tzinfo_) == TIME_ZONE_ID_INVALID) {
      // If we cannot get timezone information we fall back to CET.
      tzinfo_.Bias = -60;
      tzinfo_.StandardDate.wMonth = 10;
      tzinfo_.StandardDate.wDay = 5;
      tzinfo_.StandardDate.wHour = 3;
      tzinfo_.StandardBias = 0;
      tzinfo_.DaylightDate.wMonth = 3;
      tzinfo_.DaylightDate.wDay = 5;
      tzinfo_.DaylightDate.wHour = 2;
      tzinfo_.DaylightBias = -60;
    }
  
    // Make standard and DST timezone names.
    OS::SNPrintF(Vector<char>(std_tz_name_, kTzNameSize),
                 "%S",
                 tzinfo_.StandardName);
    std_tz_name_[kTzNameSize - 1] = '\0';
    OS::SNPrintF(Vector<char>(dst_tz_name_, kTzNameSize),
                 "%S",
                 tzinfo_.DaylightName);
    dst_tz_name_[kTzNameSize - 1] = '\0';
  
    // If OS returned empty string or resource id (like "@tzres.dll,-211")
    // simply guess the name from the UTC bias of the timezone.
    // To properly resolve the resource identifier requires a library load,
    // which is not possible in a sandbox.
    if (std_tz_name_[0] == '\0' || std_tz_name_[0] == '@') {
      OS::SNPrintF(Vector<char>(std_tz_name_, kTzNameSize - 1),
                   "%s Standard Time",
                   GuessTimezoneNameFromBias(tzinfo_.Bias));
    }
    if (dst_tz_name_[0] == '\0' || dst_tz_name_[0] == '@') {
      OS::SNPrintF(Vector<char>(dst_tz_name_, kTzNameSize - 1),
                   "%s Daylight Time",
                   GuessTimezoneNameFromBias(tzinfo_.Bias));
    }
  
    // Timezone information initialized.
    tz_initialized_ = true;
  }
  
  
  // Return the difference in milliseconds between this and another timestamp.
  int64_t Time::Diff(Time* other) {
    return (t() - other->t()) / kTimeScaler;
  }
  
  
  // Set timestamp to current time.
  void Time::SetToCurrentTime() {
    // The default GetSystemTimeAsFileTime has a ~15.5ms resolution.
    // Because we're fast, we like fast timers which have at least a
    // 1ms resolution.
    //
    // timeGetTime() provides 1ms granularity when combined with
    // timeBeginPeriod().  If the host application for v8 wants fast
    // timers, it can use timeBeginPeriod to increase the resolution.
    //
    // Using timeGetTime() has a drawback because it is a 32bit value
    // and hence rolls-over every ~49days.
    //
    // To use the clock, we use GetSystemTimeAsFileTime as our base;
    // and then use timeGetTime to extrapolate current time from the
    // start time.  To deal with rollovers, we resync the clock
    // any time when more than kMaxClockElapsedTime has passed or
    // whenever timeGetTime creates a rollover.
  
    static bool initialized = false;
    static TimeStamp init_time;
    static DWORD init_ticks;
    static const int64_t kHundredNanosecondsPerSecond = 10000000;
    static const int64_t kMaxClockElapsedTime =
        60*kHundredNanosecondsPerSecond;  // 1 minute
  
    // If we are uninitialized, we need to resync the clock.
    bool needs_resync = !initialized;
  
    // Get the current time.
    TimeStamp time_now;
    GetSystemTimeAsFileTime(&time_now.ft_);
    DWORD ticks_now = timeGetTime();
  
    // Check if we need to resync due to clock rollover.
    needs_resync |= ticks_now < init_ticks;
  
    // Check if we need to resync due to elapsed time.
    needs_resync |= (time_now.t_ - init_time.t_) > kMaxClockElapsedTime;
  
    // Resync the clock if necessary.
    if (needs_resync) {
      GetSystemTimeAsFileTime(&init_time.ft_);
      init_ticks = ticks_now = timeGetTime();
      initialized = true;
    }
  
    // Finally, compute the actual time.  Why is this so hard.
    DWORD elapsed = ticks_now - init_ticks;
    this->time_.t_ = init_time.t_ + (static_cast<int64_t>(elapsed) * 10000);
  }
  
  
  // Return the local timezone offset in milliseconds east of UTC. This
  // takes into account whether daylight saving is in effect at the time.
  // Only times in the 32-bit Unix range may be passed to this function.
  // Also, adding the time-zone offset to the input must not overflow.
  // The function EquivalentTime() in date-delay.js guarantees this.
  int64_t Time::LocalOffset() {
    // Initialize timezone information, if needed.
    TzSet();
  
    Time rounded_to_second(*this);
    rounded_to_second.t() = rounded_to_second.t() / 1000 / kTimeScaler *
        1000 * kTimeScaler;
    // Convert to local time using POSIX localtime function.
    // Windows XP Service Pack 3 made SystemTimeToTzSpecificLocalTime()
    // very slow.  Other browsers use localtime().
  
    // Convert from JavaScript milliseconds past 1/1/1970 0:00:00 to
    // POSIX seconds past 1/1/1970 0:00:00.
    double unchecked_posix_time = rounded_to_second.ToJSTime() / 1000;
    if (unchecked_posix_time > INT_MAX || unchecked_posix_time < 0) {
      return 0;
    }
    // Because _USE_32BIT_TIME_T is defined, time_t is a 32-bit int.
    time_t posix_time = static_cast<time_t>(unchecked_posix_time);
  
    // Convert to local time, as struct with fields for day, hour, year, etc.
    tm posix_local_time_struct;
    if (localtime_s(&posix_local_time_struct, &posix_time)) return 0;
    // Convert local time in struct to POSIX time as if it were a UTC time.
    time_t local_posix_time = _mkgmtime(&posix_local_time_struct);
    Time localtime(1000.0 * local_posix_time);
  
    return localtime.Diff(&rounded_to_second);
  }
  
  
  // Return whether or not daylight savings time is in effect at this time.
  bool Time::InDST() {
    // Initialize timezone information, if needed.
    TzSet();
  
    // Determine if DST is in effect at the specified time.
    bool in_dst = false;
    if (tzinfo_.StandardDate.wMonth != 0 || tzinfo_.DaylightDate.wMonth != 0) {
      // Get the local timezone offset for the timestamp in milliseconds.
      int64_t offset = LocalOffset();
  
      // Compute the offset for DST. The bias parameters in the timezone info
      // are specified in minutes. These must be converted to milliseconds.
      int64_t dstofs = -(tzinfo_.Bias + tzinfo_.DaylightBias) * kMsPerMinute;
  
      // If the local time offset equals the timezone bias plus the daylight
      // bias then DST is in effect.
      in_dst = offset == dstofs;
    }
  
    return in_dst;
  }
  
  
  // Return the daylight savings time offset for this time.
  int64_t Time::DaylightSavingsOffset() {
    return InDST() ? 60 * kMsPerMinute : 0;
  }
  
  
  // Returns a string identifying the current timezone for the
  // timestamp taking into account daylight saving.
  char* Time::LocalTimezone() {
    // Return the standard or DST time zone name based on whether daylight
    // saving is in effect at the given time.
    return InDST() ? dst_tz_name_ : std_tz_name_;
  }
  
  
  void OS::Setup() {
    // Seed the random number generator.
    // Convert the current time to a 64-bit integer first, before converting it
    // to an unsigned. Going directly can cause an overflow and the seed to be
    // set to all ones. The seed will be identical for different instances that
    // call this setup code within the same millisecond.
    uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
    srand(static_cast<unsigned int>(seed));
  }
  
  
  // Returns the accumulated user time for thread.
  int OS::GetUserTime(uint32_t* secs,  uint32_t* usecs) {
    FILETIME dummy;
    uint64_t usertime;
  
    // Get the amount of time that the thread has executed in user mode.
    if (!GetThreadTimes(GetCurrentThread(), &dummy, &dummy, &dummy,
                        reinterpret_cast<FILETIME*>(&usertime))) return -1;
  
    // Adjust the resolution to micro-seconds.
    usertime /= 10;
  
    // Convert to seconds and microseconds
    *secs = static_cast<uint32_t>(usertime / 1000000);
    *usecs = static_cast<uint32_t>(usertime % 1000000);
    return 0;
  }
  
  
  // Returns current time as the number of milliseconds since
  // 00:00:00 UTC, January 1, 1970.
  double OS::TimeCurrentMillis() {
    Time t;
    t.SetToCurrentTime();
    return t.ToJSTime();
  }
  
  // Returns the tickcounter based on timeGetTime.
  int64_t OS::Ticks() {
    return timeGetTime() * 1000;  // Convert to microseconds.
  }
  
  
  // Returns a string identifying the current timezone taking into
  // account daylight saving.
  const char* OS::LocalTimezone(double time) {
    return Time(time).LocalTimezone();
  }
  
  
  // Returns the local time offset in milliseconds east of UTC without
  // taking daylight savings time into account.
  double OS::LocalTimeOffset() {
    // Use current time, rounded to the millisecond.
    Time t(TimeCurrentMillis());
    // Time::LocalOffset inlcudes any daylight savings offset, so subtract it.
    return static_cast<double>(t.LocalOffset() - t.DaylightSavingsOffset());
  }
  
  
  // Returns the daylight savings offset in milliseconds for the given
  // time.
  double OS::DaylightSavingsOffset(double time) {
    int64_t offset = Time(time).DaylightSavingsOffset();
    return static_cast<double>(offset);
  }
  
  
  // ----------------------------------------------------------------------------
  // Win32 console output.
  //
  // If a Win32 application is linked as a console application it has a normal
  // standard output and standard error. In this case normal printf works fine
  // for output. However, if the application is linked as a GUI application,
  // the process doesn't have a console, and therefore (debugging) output is lost.
  // This is the case if we are embedded in a windows program (like a browser).
  // In order to be able to get debug output in this case the the debugging
  // facility using OutputDebugString. This output goes to the active debugger
  // for the process (if any). Else the output can be monitored using DBMON.EXE.
  
  enum OutputMode {
    UNKNOWN,  // Output method has not yet been determined.
    CONSOLE,  // Output is written to stdout.
    ODS       // Output is written to debug facility.
  };
  
  static OutputMode output_mode = UNKNOWN;  // Current output mode.
  
  
  // Determine if the process has a console for output.
  static bool HasConsole() {
    // Only check the first time. Eventual race conditions are not a problem,
    // because all threads will eventually determine the same mode.
    if (output_mode == UNKNOWN) {
      // We cannot just check that the standard output is attached to a console
      // because this would fail if output is redirected to a file. Therefore we
      // say that a process does not have an output console if either the
      // standard output handle is invalid or its file type is unknown.
      if (GetStdHandle(STD_OUTPUT_HANDLE) != INVALID_HANDLE_VALUE &&
          GetFileType(GetStdHandle(STD_OUTPUT_HANDLE)) != FILE_TYPE_UNKNOWN)
        output_mode = CONSOLE;
      else
        output_mode = ODS;
    }
    return output_mode == CONSOLE;
  }
  
  
  static void VPrintHelper(FILE* stream, const char* format, va_list args) {
    if (HasConsole()) {
      vfprintf(stream, format, args);
    } else {
      // It is important to use safe print here in order to avoid
      // overflowing the buffer. We might truncate the output, but this
      // does not crash.
      EmbeddedVector<char, 4096> buffer;
      OS::VSNPrintF(buffer, format, args);
      OutputDebugStringA(buffer.start());
    }
  }
  
  
  FILE* OS::FOpen(const char* path, const char* mode) {
    FILE* result;
    if (fopen_s(&result, path, mode) == 0) {
      return result;
    } else {
      return NULL;
    }
  }
  
  
  // Open log file in binary mode to avoid /n -> /r/n conversion.
  const char* OS::LogFileOpenMode = "wb";
  
  
  // Print (debug) message to console.
  void OS::Print(const char* format, ...) {
    va_list args;
    va_start(args, format);
    VPrint(format, args);
    va_end(args);
  }
  
  
  void OS::VPrint(const char* format, va_list args) {
    VPrintHelper(stdout, format, args);
  }
  
  
  // Print error message to console.
  void OS::PrintError(const char* format, ...) {
    va_list args;
    va_start(args, format);
    VPrintError(format, args);
    va_end(args);
  }
  
  
  void OS::VPrintError(const char* format, va_list args) {
    VPrintHelper(stderr, format, args);
  }
  
  
  int OS::SNPrintF(Vector<char> str, const char* format, ...) {
    va_list args;
    va_start(args, format);
    int result = VSNPrintF(str, format, args);
    va_end(args);
    return result;
  }
  
  
  int OS::VSNPrintF(Vector<char> str, const char* format, va_list args) {
    int n = _vsnprintf_s(str.start(), str.length(), _TRUNCATE, format, args);
    // Make sure to zero-terminate the string if the output was
    // truncated or if there was an error.
    if (n < 0 || n >= str.length()) {
      str[str.length() - 1] = '\0';
      return -1;
    } else {
      return n;
    }
  }
  
  
  char* OS::StrChr(char* str, int c) {
    return const_cast<char*>(strchr(str, c));
  }
  
  
  void OS::StrNCpy(Vector<char> dest, const char* src, size_t n) {
    int result = strncpy_s(dest.start(), dest.length(), src, n);
    USE(result);
    ASSERT(result == 0);
  }
  
  
  // We keep the lowest and highest addresses mapped as a quick way of
  // determining that pointers are outside the heap (used mostly in assertions
  // and verification).  The estimate is conservative, ie, not all addresses in
  // 'allocated' space are actually allocated to our heap.  The range is
  // [lowest, highest), inclusive on the low and and exclusive on the high end.
  static void* lowest_ever_allocated = reinterpret_cast<void*>(-1);
  static void* highest_ever_allocated = reinterpret_cast<void*>(0);
  
  
  static void UpdateAllocatedSpaceLimits(void* address, int size) {
    lowest_ever_allocated = Min(lowest_ever_allocated, address);
    highest_ever_allocated =
        Max(highest_ever_allocated,
            reinterpret_cast<void*>(reinterpret_cast<char*>(address) + size));
  }
  
  
  bool OS::IsOutsideAllocatedSpace(void* pointer) {
    if (pointer < lowest_ever_allocated || pointer >= highest_ever_allocated)
      return true;
    // Ask the Windows API
    if (IsBadWritePtr(pointer, 1))
      return true;
    return false;
  }
  
  
  // Get the system's page size used by VirtualAlloc() or the next power
  // of two. The reason for always returning a power of two is that the
  // rounding up in OS::Allocate expects that.
  static size_t GetPageSize() {
    static size_t page_size = 0;
    if (page_size == 0) {
      SYSTEM_INFO info;
      GetSystemInfo(&info);
      page_size = RoundUpToPowerOf2(info.dwPageSize);
    }
    return page_size;
  }
  
  
  // The allocation alignment is the guaranteed alignment for
  // VirtualAlloc'ed blocks of memory.
  size_t OS::AllocateAlignment() {
    static size_t allocate_alignment = 0;
    if (allocate_alignment == 0) {
      SYSTEM_INFO info;
      GetSystemInfo(&info);
      allocate_alignment = info.dwAllocationGranularity;
    }
    return allocate_alignment;
  }
  
  
  void* OS::Allocate(const size_t requested,
                     size_t* allocated,
                     bool is_executable) {
    // VirtualAlloc rounds allocated size to page size automatically.
    size_t msize = RoundUp(requested, GetPageSize());
  
    // Windows XP SP2 allows Data Excution Prevention (DEP).
    int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
    LPVOID mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
    if (mbase == NULL) {
      LOG(StringEvent("OS::Allocate", "VirtualAlloc failed"));
      return NULL;
    }
  
    ASSERT(IsAligned(reinterpret_cast<size_t>(mbase), OS::AllocateAlignment()));
  
    *allocated = msize;
    UpdateAllocatedSpaceLimits(mbase, msize);
    return mbase;
  }
  
  
  void OS::Free(void* address, const size_t size) {
    // TODO(1240712): VirtualFree has a return value which is ignored here.
    VirtualFree(address, 0, MEM_RELEASE);
    USE(size);
  }
  
  
  #ifdef ENABLE_HEAP_PROTECTION
  
  void OS::Protect(void* address, size_t size) {
    // TODO(1240712): VirtualProtect has a return value which is ignored here.
    DWORD old_protect;
    VirtualProtect(address, size, PAGE_READONLY, &old_protect);
  }
  
  
  void OS::Unprotect(void* address, size_t size, bool is_executable) {
    // TODO(1240712): VirtualProtect has a return value which is ignored here.
    DWORD new_protect = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
    DWORD old_protect;
    VirtualProtect(address, size, new_protect, &old_protect);
  }
  
  #endif
  
  
  void OS::Sleep(int milliseconds) {
    ::Sleep(milliseconds);
  }
  
  
  void OS::Abort() {
    if (!IsDebuggerPresent()) {
  #ifdef _MSC_VER
      // Make the MSVCRT do a silent abort.
      _set_abort_behavior(0, _WRITE_ABORT_MSG);
      _set_abort_behavior(0, _CALL_REPORTFAULT);
  #endif  // _MSC_VER
      abort();
    } else {
      DebugBreak();
    }
  }
  
  
  void OS::DebugBreak() {
  #ifdef _MSC_VER
    __debugbreak();
  #else
    ::DebugBreak();
  #endif
  }
  
  
  class Win32MemoryMappedFile : public OS::MemoryMappedFile {
   public:
    Win32MemoryMappedFile(HANDLE file, HANDLE file_mapping, void* memory)
      : file_(file), file_mapping_(file_mapping), memory_(memory) { }
    virtual ~Win32MemoryMappedFile();
    virtual void* memory() { return memory_; }
   private:
    HANDLE file_;
    HANDLE file_mapping_;
    void* memory_;
  };
  
  
  OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
      void* initial) {
    // Open a physical file
    HANDLE file = CreateFileA(name, GENERIC_READ | GENERIC_WRITE,
        FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, 0, NULL);
    if (file == NULL) return NULL;
    // Create a file mapping for the physical file
    HANDLE file_mapping = CreateFileMapping(file, NULL,
        PAGE_READWRITE, 0, static_cast<DWORD>(size), NULL);
    if (file_mapping == NULL) return NULL;
    // Map a view of the file into memory
    void* memory = MapViewOfFile(file_mapping, FILE_MAP_ALL_ACCESS, 0, 0, size);
    if (memory) memmove(memory, initial, size);
    return new Win32MemoryMappedFile(file, file_mapping, memory);
  }
  
  
  Win32MemoryMappedFile::~Win32MemoryMappedFile() {
    if (memory_ != NULL)
      UnmapViewOfFile(memory_);
    CloseHandle(file_mapping_);
    CloseHandle(file_);
  }
  
  
  // The following code loads functions defined in DbhHelp.h and TlHelp32.h
  // dynamically. This is to avoid being depending on dbghelp.dll and
  // tlhelp32.dll when running (the functions in tlhelp32.dll have been moved to
  // kernel32.dll at some point so loading functions defines in TlHelp32.h
  // dynamically might not be necessary any more - for some versions of Windows?).
  
  // Function pointers to functions dynamically loaded from dbghelp.dll.
  #define DBGHELP_FUNCTION_LIST(V)  \
    V(SymInitialize)                \
    V(SymGetOptions)                \
    V(SymSetOptions)                \
    V(SymGetSearchPath)             \
    V(SymLoadModule64)              \
    V(StackWalk64)                  \
    V(SymGetSymFromAddr64)          \
    V(SymGetLineFromAddr64)         \
    V(SymFunctionTableAccess64)     \
    V(SymGetModuleBase64)
  
  // Function pointers to functions dynamically loaded from dbghelp.dll.
  #define TLHELP32_FUNCTION_LIST(V)  \
    V(CreateToolhelp32Snapshot)      \
    V(Module32FirstW)                \
    V(Module32NextW)
  
  // Define the decoration to use for the type and variable name used for
  // dynamically loaded DLL function..
  #define DLL_FUNC_TYPE(name) _##name##_
  #define DLL_FUNC_VAR(name) _##name
  
  // Define the type for each dynamically loaded DLL function. The function
  // definitions are copied from DbgHelp.h and TlHelp32.h. The IN and VOID macros
  // from the Windows include files are redefined here to have the function
  // definitions to be as close to the ones in the original .h files as possible.
  #ifndef IN
  #define IN
  #endif
  #ifndef VOID
  #define VOID void
  #endif
  
  // DbgHelp isn't supported on MinGW yet
  #ifndef __MINGW32__
  // DbgHelp.h functions.
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(SymInitialize))(IN HANDLE hProcess,
                                                         IN PSTR UserSearchPath,
                                                         IN BOOL fInvadeProcess);
  typedef DWORD (__stdcall *DLL_FUNC_TYPE(SymGetOptions))(VOID);
  typedef DWORD (__stdcall *DLL_FUNC_TYPE(SymSetOptions))(IN DWORD SymOptions);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(SymGetSearchPath))(
      IN HANDLE hProcess,
      OUT PSTR SearchPath,
      IN DWORD SearchPathLength);
  typedef DWORD64 (__stdcall *DLL_FUNC_TYPE(SymLoadModule64))(
      IN HANDLE hProcess,
      IN HANDLE hFile,
      IN PSTR ImageName,
      IN PSTR ModuleName,
      IN DWORD64 BaseOfDll,
      IN DWORD SizeOfDll);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(StackWalk64))(
      DWORD MachineType,
      HANDLE hProcess,
      HANDLE hThread,
      LPSTACKFRAME64 StackFrame,
      PVOID ContextRecord,
      PREAD_PROCESS_MEMORY_ROUTINE64 ReadMemoryRoutine,
      PFUNCTION_TABLE_ACCESS_ROUTINE64 FunctionTableAccessRoutine,
      PGET_MODULE_BASE_ROUTINE64 GetModuleBaseRoutine,
      PTRANSLATE_ADDRESS_ROUTINE64 TranslateAddress);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(SymGetSymFromAddr64))(
      IN HANDLE hProcess,
      IN DWORD64 qwAddr,
      OUT PDWORD64 pdwDisplacement,
      OUT PIMAGEHLP_SYMBOL64 Symbol);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(SymGetLineFromAddr64))(
      IN HANDLE hProcess,
      IN DWORD64 qwAddr,
      OUT PDWORD pdwDisplacement,
      OUT PIMAGEHLP_LINE64 Line64);
  // DbgHelp.h typedefs. Implementation found in dbghelp.dll.
  typedef PVOID (__stdcall *DLL_FUNC_TYPE(SymFunctionTableAccess64))(
      HANDLE hProcess,
      DWORD64 AddrBase);  // DbgHelp.h typedef PFUNCTION_TABLE_ACCESS_ROUTINE64
  typedef DWORD64 (__stdcall *DLL_FUNC_TYPE(SymGetModuleBase64))(
      HANDLE hProcess,
      DWORD64 AddrBase);  // DbgHelp.h typedef PGET_MODULE_BASE_ROUTINE64
  
  // TlHelp32.h functions.
  typedef HANDLE (__stdcall *DLL_FUNC_TYPE(CreateToolhelp32Snapshot))(
      DWORD dwFlags,
      DWORD th32ProcessID);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(Module32FirstW))(HANDLE hSnapshot,
                                                          LPMODULEENTRY32W lpme);
  typedef BOOL (__stdcall *DLL_FUNC_TYPE(Module32NextW))(HANDLE hSnapshot,
                                                         LPMODULEENTRY32W lpme);
  
  #undef IN
  #undef VOID
  
  // Declare a variable for each dynamically loaded DLL function.
  #define DEF_DLL_FUNCTION(name) DLL_FUNC_TYPE(name) DLL_FUNC_VAR(name) = NULL;
  DBGHELP_FUNCTION_LIST(DEF_DLL_FUNCTION)
  TLHELP32_FUNCTION_LIST(DEF_DLL_FUNCTION)
  #undef DEF_DLL_FUNCTION
  
  // Load the functions. This function has a lot of "ugly" macros in order to
  // keep down code duplication.
  
  static bool LoadDbgHelpAndTlHelp32() {
    static bool dbghelp_loaded = false;
  
    if (dbghelp_loaded) return true;
  
    HMODULE module;
  
    // Load functions from the dbghelp.dll module.
    module = LoadLibrary(TEXT("dbghelp.dll"));
    if (module == NULL) {
      return false;
    }
  
  #define LOAD_DLL_FUNC(name)                                                 \
    DLL_FUNC_VAR(name) =                                                      \
        reinterpret_cast<DLL_FUNC_TYPE(name)>(GetProcAddress(module, #name));
  
  DBGHELP_FUNCTION_LIST(LOAD_DLL_FUNC)
  
  #undef LOAD_DLL_FUNC
  
    // Load functions from the kernel32.dll module (the TlHelp32.h function used
    // to be in tlhelp32.dll but are now moved to kernel32.dll).
    module = LoadLibrary(TEXT("kernel32.dll"));
    if (module == NULL) {
      return false;
    }
  
  #define LOAD_DLL_FUNC(name)                                                 \
    DLL_FUNC_VAR(name) =                                                      \
        reinterpret_cast<DLL_FUNC_TYPE(name)>(GetProcAddress(module, #name));
  
  TLHELP32_FUNCTION_LIST(LOAD_DLL_FUNC)
  
  #undef LOAD_DLL_FUNC
  
    // Check that all functions where loaded.
    bool result =
  #define DLL_FUNC_LOADED(name) (DLL_FUNC_VAR(name) != NULL) &&
  
  DBGHELP_FUNCTION_LIST(DLL_FUNC_LOADED)
  TLHELP32_FUNCTION_LIST(DLL_FUNC_LOADED)
  
  #undef DLL_FUNC_LOADED
    true;
  
    dbghelp_loaded = result;
    return result;
    // NOTE: The modules are never unloaded and will stay around until the
    // application is closed.
  }
  
  
  // Load the symbols for generating stack traces.
  static bool LoadSymbols(HANDLE process_handle) {
    static bool symbols_loaded = false;
  
    if (symbols_loaded) return true;
  
    BOOL ok;
  
    // Initialize the symbol engine.
    ok = _SymInitialize(process_handle,  // hProcess
                        NULL,            // UserSearchPath
                        FALSE);          // fInvadeProcess
    if (!ok) return false;
  
    DWORD options = _SymGetOptions();
    options |= SYMOPT_LOAD_LINES;
    options |= SYMOPT_FAIL_CRITICAL_ERRORS;
    options = _SymSetOptions(options);
  
    char buf[OS::kStackWalkMaxNameLen] = {0};
    ok = _SymGetSearchPath(process_handle, buf, OS::kStackWalkMaxNameLen);
    if (!ok) {
      int err = GetLastError();
      PrintF("%d\n", err);
      return false;
    }
  
    HANDLE snapshot = _CreateToolhelp32Snapshot(
        TH32CS_SNAPMODULE,       // dwFlags
        GetCurrentProcessId());  // th32ProcessId
    if (snapshot == INVALID_HANDLE_VALUE) return false;
    MODULEENTRY32W module_entry;
    module_entry.dwSize = sizeof(module_entry);  // Set the size of the structure.
    BOOL cont = _Module32FirstW(snapshot, &module_entry);
    while (cont) {
      DWORD64 base;
      // NOTE the SymLoadModule64 function has the peculiarity of accepting a
      // both unicode and ASCII strings even though the parameter is PSTR.
      base = _SymLoadModule64(
          process_handle,                                       // hProcess
          0,                                                    // hFile
          reinterpret_cast<PSTR>(module_entry.szExePath),       // ImageName
          reinterpret_cast<PSTR>(module_entry.szModule),        // ModuleName
          reinterpret_cast<DWORD64>(module_entry.modBaseAddr),  // BaseOfDll
          module_entry.modBaseSize);                            // SizeOfDll
      if (base == 0) {
        int err = GetLastError();
        if (err != ERROR_MOD_NOT_FOUND &&
            err != ERROR_INVALID_HANDLE) return false;
      }
      LOG(SharedLibraryEvent(
              module_entry.szExePath,
              reinterpret_cast<unsigned int>(module_entry.modBaseAddr),
              reinterpret_cast<unsigned int>(module_entry.modBaseAddr +
                                             module_entry.modBaseSize)));
      cont = _Module32NextW(snapshot, &module_entry);
    }
    CloseHandle(snapshot);
  
    symbols_loaded = true;
    return true;
  }
  
  
  void OS::LogSharedLibraryAddresses() {
    // SharedLibraryEvents are logged when loading symbol information.
    // Only the shared libraries loaded at the time of the call to
    // LogSharedLibraryAddresses are logged.  DLLs loaded after
    // initialization are not accounted for.
    if (!LoadDbgHelpAndTlHelp32()) return;
    HANDLE process_handle = GetCurrentProcess();
    LoadSymbols(process_handle);
  }
  
  
  // Walk the stack using the facilities in dbghelp.dll and tlhelp32.dll
  
  // Switch off warning 4748 (/GS can not protect parameters and local variables
  // from local buffer overrun because optimizations are disabled in function) as
  // it is triggered by the use of inline assembler.
  #pragma warning(push)
  #pragma warning(disable : 4748)
  int OS::StackWalk(Vector<OS::StackFrame> frames) {
    BOOL ok;
  
    // Load the required functions from DLL's.
    if (!LoadDbgHelpAndTlHelp32()) return kStackWalkError;
  
    // Get the process and thread handles.
    HANDLE process_handle = GetCurrentProcess();
    HANDLE thread_handle = GetCurrentThread();
  
    // Read the symbols.
    if (!LoadSymbols(process_handle)) return kStackWalkError;
  
    // Capture current context.
    CONTEXT context;
    memset(&context, 0, sizeof(context));
    context.ContextFlags = CONTEXT_CONTROL;
    context.ContextFlags = CONTEXT_CONTROL;
  #ifdef  _WIN64
    // TODO(X64): Implement context capture.
  #else
    __asm    call x
    __asm x: pop eax
    __asm    mov context.Eip, eax
    __asm    mov context.Ebp, ebp
    __asm    mov context.Esp, esp
    // NOTE: At some point, we could use RtlCaptureContext(&context) to
    // capture the context instead of inline assembler. However it is
    // only available on XP, Vista, Server 2003 and Server 2008 which
    // might not be sufficient.
  #endif
  
    // Initialize the stack walking
    STACKFRAME64 stack_frame;
    memset(&stack_frame, 0, sizeof(stack_frame));
  #ifdef  _WIN64
    stack_frame.AddrPC.Offset = context.Rip;
    stack_frame.AddrFrame.Offset = context.Rbp;
    stack_frame.AddrStack.Offset = context.Rsp;
  #else
    stack_frame.AddrPC.Offset = context.Eip;
    stack_frame.AddrFrame.Offset = context.Ebp;
    stack_frame.AddrStack.Offset = context.Esp;
  #endif
    stack_frame.AddrPC.Mode = AddrModeFlat;
    stack_frame.AddrFrame.Mode = AddrModeFlat;
    stack_frame.AddrStack.Mode = AddrModeFlat;
    int frames_count = 0;
  
    // Collect stack frames.
    int frames_size = frames.length();
    while (frames_count < frames_size) {
      ok = _StackWalk64(
          IMAGE_FILE_MACHINE_I386,    // MachineType
          process_handle,             // hProcess
          thread_handle,              // hThread
          &stack_frame,               // StackFrame
          &context,                   // ContextRecord
          NULL,                       // ReadMemoryRoutine
          _SymFunctionTableAccess64,  // FunctionTableAccessRoutine
          _SymGetModuleBase64,        // GetModuleBaseRoutine
          NULL);                      // TranslateAddress
      if (!ok) break;
  
      // Store the address.
      ASSERT((stack_frame.AddrPC.Offset >> 32) == 0);  // 32-bit address.
      frames[frames_count].address =
          reinterpret_cast<void*>(stack_frame.AddrPC.Offset);
  
      // Try to locate a symbol for this frame.
      DWORD64 symbol_displacement;
      IMAGEHLP_SYMBOL64* symbol = NULL;
      symbol = NewArray<IMAGEHLP_SYMBOL64>(kStackWalkMaxNameLen);
      if (!symbol) return kStackWalkError;  // Out of memory.
      memset(symbol, 0, sizeof(IMAGEHLP_SYMBOL64) + kStackWalkMaxNameLen);
      symbol->SizeOfStruct = sizeof(IMAGEHLP_SYMBOL64);
      symbol->MaxNameLength = kStackWalkMaxNameLen;
      ok = _SymGetSymFromAddr64(process_handle,             // hProcess
                                stack_frame.AddrPC.Offset,  // Address
                                &symbol_displacement,       // Displacement
                                symbol);                    // Symbol
      if (ok) {
        // Try to locate more source information for the symbol.
        IMAGEHLP_LINE64 Line;
        memset(&Line, 0, sizeof(Line));
        Line.SizeOfStruct = sizeof(Line);
        DWORD line_displacement;
        ok = _SymGetLineFromAddr64(
            process_handle,             // hProcess
            stack_frame.AddrPC.Offset,  // dwAddr
            &line_displacement,         // pdwDisplacement
            &Line);                     // Line
        // Format a text representation of the frame based on the information
        // available.
        if (ok) {
          SNPrintF(MutableCStrVector(frames[frames_count].text,
                                     kStackWalkMaxTextLen),
                   "%s %s:%d:%d",
                   symbol->Name, Line.FileName, Line.LineNumber,
                   line_displacement);
        } else {
          SNPrintF(MutableCStrVector(frames[frames_count].text,
                                     kStackWalkMaxTextLen),
                   "%s",
                   symbol->Name);
        }
        // Make sure line termination is in place.
        frames[frames_count].text[kStackWalkMaxTextLen - 1] = '\0';
      } else {
        // No text representation of this frame
        frames[frames_count].text[0] = '\0';
  
        // Continue if we are just missing a module (for non C/C++ frames a
        // module will never be found).
        int err = GetLastError();
        if (err != ERROR_MOD_NOT_FOUND) {
          DeleteArray(symbol);
          break;
        }
      }
      DeleteArray(symbol);
  
      frames_count++;
    }
  
    // Return the number of frames filled in.
    return frames_count;
  }
  
  // Restore warnings to previous settings.
  #pragma warning(pop)
  
  #else  // __MINGW32__
  void OS::LogSharedLibraryAddresses() { }
  int OS::StackWalk(Vector<OS::StackFrame> frames) { return 0; }
  #endif  // __MINGW32__
  
  
  double OS::nan_value() {
  #ifdef _MSC_VER
    static const __int64 nanval = 0xfff8000000000000;
    return *reinterpret_cast<const double*>(&nanval);
  #else  // _MSC_VER
    return NAN;
  #endif  // _MSC_VER
  }
  
  
  int OS::ActivationFrameAlignment() {
  #ifdef _WIN64
    return 16;  // Windows 64-bit ABI requires the stack to be 16-byte aligned.
  #else
    return 8;  // Floating-point math runs faster with 8-byte alignment.
  #endif
  }
  
  
  bool VirtualMemory::IsReserved() {
    return address_ != NULL;
  }
  
  
  VirtualMemory::VirtualMemory(size_t size) {
    address_ = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
    size_ = size;
  }
  
  
  VirtualMemory::~VirtualMemory() {
    if (IsReserved()) {
      if (0 == VirtualFree(address(), 0, MEM_RELEASE)) address_ = NULL;
    }
  }
  
  
  bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
    int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
    if (NULL == VirtualAlloc(address, size, MEM_COMMIT, prot)) {
      return false;
    }
  
    UpdateAllocatedSpaceLimits(address, size);
    return true;
  }
  
  
  bool VirtualMemory::Uncommit(void* address, size_t size) {
    ASSERT(IsReserved());
    return VirtualFree(address, size, MEM_DECOMMIT) != FALSE;
  }
  
  
  // ----------------------------------------------------------------------------
  // Win32 thread support.
  
  // Definition of invalid thread handle and id.
  static const HANDLE kNoThread = INVALID_HANDLE_VALUE;
  static const DWORD kNoThreadId = 0;
  
  
  class ThreadHandle::PlatformData : public Malloced {
   public:
    explicit PlatformData(ThreadHandle::Kind kind) {
      Initialize(kind);
    }
  
    void Initialize(ThreadHandle::Kind kind) {
      switch (kind) {
        case ThreadHandle::SELF: tid_ = GetCurrentThreadId(); break;
        case ThreadHandle::INVALID: tid_ = kNoThreadId; break;
      }
    }
    DWORD tid_;  // Win32 thread identifier.
  };
  
  
  // Entry point for threads. The supplied argument is a pointer to the thread
  // object. The entry function dispatches to the run method in the thread
  // object. It is important that this function has __stdcall calling
  // convention.
  static unsigned int __stdcall ThreadEntry(void* arg) {
    Thread* thread = reinterpret_cast<Thread*>(arg);
    // This is also initialized by the last parameter to _beginthreadex() but we
    // don't know which thread will run first (the original thread or the new
    // one) so we initialize it here too.
    thread->thread_handle_data()->tid_ = GetCurrentThreadId();
    thread->Run();
    return 0;
  }
  
  
  // Initialize thread handle to invalid handle.
  ThreadHandle::ThreadHandle(ThreadHandle::Kind kind) {
    data_ = new PlatformData(kind);
  }
  
  
  ThreadHandle::~ThreadHandle() {
    delete data_;
  }
  
  
  // The thread is running if it has the same id as the current thread.
  bool ThreadHandle::IsSelf() const {
    return GetCurrentThreadId() == data_->tid_;
  }
  
  
  // Test for invalid thread handle.
  bool ThreadHandle::IsValid() const {
    return data_->tid_ != kNoThreadId;
  }
  
  
  void ThreadHandle::Initialize(ThreadHandle::Kind kind) {
    data_->Initialize(kind);
  }
  
  
  class Thread::PlatformData : public Malloced {
   public:
    explicit PlatformData(HANDLE thread) : thread_(thread) {}
    HANDLE thread_;
  };
  
  
  // Initialize a Win32 thread object. The thread has an invalid thread
  // handle until it is started.
  
  Thread::Thread() : ThreadHandle(ThreadHandle::INVALID) {
    data_ = new PlatformData(kNoThread);
  }
  
  
  // Close our own handle for the thread.
  Thread::~Thread() {
    if (data_->thread_ != kNoThread) CloseHandle(data_->thread_);
    delete data_;
  }
  
  
  // Create a new thread. It is important to use _beginthreadex() instead of
  // the Win32 function CreateThread(), because the CreateThread() does not
  // initialize thread specific structures in the C runtime library.
  void Thread::Start() {
    data_->thread_ = reinterpret_cast<HANDLE>(
        _beginthreadex(NULL,
                       0,
                       ThreadEntry,
                       this,
                       0,
                       reinterpret_cast<unsigned int*>(
                           &thread_handle_data()->tid_)));
    ASSERT(IsValid());
  }
  
  
  // Wait for thread to terminate.
  void Thread::Join() {
    WaitForSingleObject(data_->thread_, INFINITE);
  }
  
  
  Thread::LocalStorageKey Thread::CreateThreadLocalKey() {
    DWORD result = TlsAlloc();
    ASSERT(result != TLS_OUT_OF_INDEXES);
    return static_cast<LocalStorageKey>(result);
  }
  
  
  void Thread::DeleteThreadLocalKey(LocalStorageKey key) {
    BOOL result = TlsFree(static_cast<DWORD>(key));
    USE(result);
    ASSERT(result);
  }
  
  
  void* Thread::GetThreadLocal(LocalStorageKey key) {
    return TlsGetValue(static_cast<DWORD>(key));
  }
  
  
  void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
    BOOL result = TlsSetValue(static_cast<DWORD>(key), value);
    USE(result);
    ASSERT(result);
  }
  
  
  
  void Thread::YieldCPU() {
    Sleep(0);
  }
  
  
  // ----------------------------------------------------------------------------
  // Win32 mutex support.
  //
  // On Win32 mutexes are implemented using CRITICAL_SECTION objects. These are
  // faster than Win32 Mutex objects because they are implemented using user mode
  // atomic instructions. Therefore we only do ring transitions if there is lock
  // contention.
  
  class Win32Mutex : public Mutex {
   public:
  
    Win32Mutex() { InitializeCriticalSection(&cs_); }
  
    ~Win32Mutex() { DeleteCriticalSection(&cs_); }
  
    int Lock() {
      EnterCriticalSection(&cs_);
      return 0;
    }
  
    int Unlock() {
      LeaveCriticalSection(&cs_);
      return 0;
    }
  
   private:
    CRITICAL_SECTION cs_;  // Critical section used for mutex
  };
  
  
  Mutex* OS::CreateMutex() {
    return new Win32Mutex();
  }
  
  
  // ----------------------------------------------------------------------------
  // Win32 semaphore support.
  //
  // On Win32 semaphores are implemented using Win32 Semaphore objects. The
  // semaphores are anonymous. Also, the semaphores are initialized to have
  // no upper limit on count.
  
  
  class Win32Semaphore : public Semaphore {
   public:
    explicit Win32Semaphore(int count) {
      sem = ::CreateSemaphoreA(NULL, count, 0x7fffffff, NULL);
    }
  
    ~Win32Semaphore() {
      CloseHandle(sem);
    }
  
    void Wait() {
      WaitForSingleObject(sem, INFINITE);
    }
  
    bool Wait(int timeout) {
      // Timeout in Windows API is in milliseconds.
      DWORD millis_timeout = timeout / 1000;
      return WaitForSingleObject(sem, millis_timeout) != WAIT_TIMEOUT;
    }
  
    void Signal() {
      LONG dummy;
      ReleaseSemaphore(sem, 1, &dummy);
    }
  
   private:
    HANDLE sem;
  };
  
  
  Semaphore* OS::CreateSemaphore(int count) {
    return new Win32Semaphore(count);
  }
  
  
  // ----------------------------------------------------------------------------
  // Win32 socket support.
  //
  
  class Win32Socket : public Socket {
   public:
    explicit Win32Socket() {
      // Create the socket.
      socket_ = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    }
    explicit Win32Socket(SOCKET socket): socket_(socket) { }
    virtual ~Win32Socket() { Shutdown(); }
  
    // Server initialization.
    bool Bind(const int port);
    bool Listen(int backlog) const;
    Socket* Accept() const;
  
    // Client initialization.
    bool Connect(const char* host, const char* port);
  
    // Shutdown socket for both read and write.
    bool Shutdown();
  
    // Data Transimission
    int Send(const char* data, int len) const;
    int Receive(char* data, int len) const;
  
    bool SetReuseAddress(bool reuse_address);
  
    bool IsValid() const { return socket_ != INVALID_SOCKET; }
  
   private:
    SOCKET socket_;
  };
  
  
  bool Win32Socket::Bind(const int port) {
    if (!IsValid())  {
      return false;
    }
  
    sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    addr.sin_port = htons(port);
    int status = bind(socket_,
                      reinterpret_cast<struct sockaddr *>(&addr),
                      sizeof(addr));
    return status == 0;
  }
  
  
  bool Win32Socket::Listen(int backlog) const {
    if (!IsValid()) {
      return false;
    }
  
    int status = listen(socket_, backlog);
    return status == 0;
  }
  
  
  Socket* Win32Socket::Accept() const {
    if (!IsValid()) {
      return NULL;
    }
  
    SOCKET socket = accept(socket_, NULL, NULL);
    if (socket == INVALID_SOCKET) {
      return NULL;
    } else {
      return new Win32Socket(socket);
    }
  }
  
  
  bool Win32Socket::Connect(const char* host, const char* port) {
    if (!IsValid()) {
      return false;
    }
  
    // Lookup host and port.
    struct addrinfo *result = NULL;
    struct addrinfo hints;
    memset(&hints, 0, sizeof(addrinfo));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    int status = getaddrinfo(host, port, &hints, &result);
    if (status != 0) {
      return false;
    }
  
    // Connect.
    status = connect(socket_, result->ai_addr, result->ai_addrlen);
    freeaddrinfo(result);
    return status == 0;
  }
  
  
  bool Win32Socket::Shutdown() {
    if (IsValid()) {
      // Shutdown socket for both read and write.
      int status = shutdown(socket_, SD_BOTH);
      closesocket(socket_);
      socket_ = INVALID_SOCKET;
      return status == SOCKET_ERROR;
    }
    return true;
  }
  
  
  int Win32Socket::Send(const char* data, int len) const {
    int status = send(socket_, data, len, 0);
    return status;
  }
  
  
  int Win32Socket::Receive(char* data, int len) const {
    int status = recv(socket_, data, len, 0);
    return status;
  }
  
  
  bool Win32Socket::SetReuseAddress(bool reuse_address) {
    BOOL on = reuse_address ? TRUE : FALSE;
    int status = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
                            reinterpret_cast<char*>(&on), sizeof(on));
    return status == SOCKET_ERROR;
  }
  
  
  bool Socket::Setup() {
    // Initialize Winsock32
    int err;
    WSADATA winsock_data;
    WORD version_requested = MAKEWORD(1, 0);
    err = WSAStartup(version_requested, &winsock_data);
    if (err != 0) {
      PrintF("Unable to initialize Winsock, err = %d\n", Socket::LastError());
    }
  
    return err == 0;
  }
  
  
  int Socket::LastError() {
    return WSAGetLastError();
  }
  
  
  uint16_t Socket::HToN(uint16_t value) {
    return htons(value);
  }
  
  
  uint16_t Socket::NToH(uint16_t value) {
    return ntohs(value);
  }
  
  
  uint32_t Socket::HToN(uint32_t value) {
    return htonl(value);
  }
  
  
  uint32_t Socket::NToH(uint32_t value) {
    return ntohl(value);
  }
  
  
  Socket* OS::CreateSocket() {
    return new Win32Socket();
  }
  
  
  #ifdef ENABLE_LOGGING_AND_PROFILING
  
  // ----------------------------------------------------------------------------
  // Win32 profiler support.
  //
  // On win32 we use a sampler thread with high priority to sample the program
  // counter for the profiled thread.
  
  class Sampler::PlatformData : public Malloced {
   public:
    explicit PlatformData(Sampler* sampler) {
      sampler_ = sampler;
      sampler_thread_ = INVALID_HANDLE_VALUE;
      profiled_thread_ = INVALID_HANDLE_VALUE;
    }
  
    Sampler* sampler_;
    HANDLE sampler_thread_;
    HANDLE profiled_thread_;
  
    // Sampler thread handler.
    void Runner() {
      // Context used for sampling the register state of the profiled thread.
      CONTEXT context;
      memset(&context, 0, sizeof(context));
      // Loop until the sampler is disengaged.
      while (sampler_->IsActive()) {
        TickSample sample;
  
        // If profiling, we record the pc and sp of the profiled thread.
        if (sampler_->IsProfiling()
            && SuspendThread(profiled_thread_) != (DWORD)-1) {
          context.ContextFlags = CONTEXT_FULL;
          if (GetThreadContext(profiled_thread_, &context) != 0) {
  #if V8_HOST_ARCH_X64
            UNIMPLEMENTED();
            sample.pc = context.Rip;
            sample.sp = context.Rsp;
            sample.fp = context.Rbp;
  #else
            sample.pc = context.Eip;
            sample.sp = context.Esp;
            sample.fp = context.Ebp;
  #endif
            sampler_->SampleStack(&sample);
          }
          ResumeThread(profiled_thread_);
        }
  
        // We always sample the VM state.
        sample.state = Logger::state();
        // Invoke tick handler with program counter and stack pointer.
        sampler_->Tick(&sample);
  
        // Wait until next sampling.
        Sleep(sampler_->interval_);
      }
    }
  };
  
  
  // Entry point for sampler thread.
  static unsigned int __stdcall SamplerEntry(void* arg) {
    Sampler::PlatformData* data =
        reinterpret_cast<Sampler::PlatformData*>(arg);
    data->Runner();
    return 0;
  }
  
  
  // Initialize a profile sampler.
  Sampler::Sampler(int interval, bool profiling)
      : interval_(interval), profiling_(profiling), active_(false) {
    data_ = new PlatformData(this);
  }
  
  
  Sampler::~Sampler() {
    delete data_;
  }
  
  
  // Start profiling.
  void Sampler::Start() {
    // If we are profiling, we need to be able to access the calling
    // thread.
    if (IsProfiling()) {
      // Get a handle to the calling thread. This is the thread that we are
      // going to profile. We need to make a copy of the handle because we are
      // going to use it in the sampler thread. Using GetThreadHandle() will
      // not work in this case. We're using OpenThread because DuplicateHandle
      // for some reason doesn't work in Chrome's sandbox.
      data_->profiled_thread_ = OpenThread(THREAD_GET_CONTEXT |
                                           THREAD_SUSPEND_RESUME |
                                           THREAD_QUERY_INFORMATION,
                                           FALSE,
                                           GetCurrentThreadId());
      BOOL ok = data_->profiled_thread_ != NULL;
      if (!ok) return;
    }
  
    // Start sampler thread.
    unsigned int tid;
    active_ = true;
    data_->sampler_thread_ = reinterpret_cast<HANDLE>(
        _beginthreadex(NULL, 0, SamplerEntry, data_, 0, &tid));
    // Set thread to high priority to increase sampling accuracy.
    SetThreadPriority(data_->sampler_thread_, THREAD_PRIORITY_TIME_CRITICAL);
  }
  
  
  // Stop profiling.
  void Sampler::Stop() {
    // Seting active to false triggers termination of the sampler
    // thread.
    active_ = false;
  
    // Wait for sampler thread to terminate.
    WaitForSingleObject(data_->sampler_thread_, INFINITE);
  
    // Release the thread handles
    CloseHandle(data_->sampler_thread_);
    CloseHandle(data_->profiled_thread_);
  }
  
  
  #endif  // ENABLE_LOGGING_AND_PROFILING
  
  } }  // namespace v8::internal
  