third_party/llvm-subzero/include/llvm/Support/TimeValue.h - SwiftShader - Git at Google

 //===-- TimeValue.h - Declare OS TimeValue Concept --------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 //  This header file declares the operating system TimeValue concept.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_SUPPORT_TIMEVALUE_H
 #define LLVM_SUPPORT_TIMEVALUE_H

 #include "llvm/Support/DataTypes.h"
 #include <string>

 namespace llvm {
 namespace sys {
   /// This class is used where a precise fixed point in time is required. The
   /// range of TimeValue spans many hundreds of billions of years both past and
   /// present.  The precision of TimeValue is to the nanosecond. However, the
   /// actual precision of its values will be determined by the resolution of
   /// the system clock. The TimeValue class is used in conjunction with several
   /// other lib/System interfaces to specify the time at which a call should
   /// timeout, etc.
   /// @since 1.4
   /// @brief Provides an abstraction for a fixed point in time.
   class TimeValue {

   /// @name Constants
   /// @{
   public:

     /// A constant TimeValue representing the smallest time
     /// value permissible by the class. MinTime is some point
     /// in the distant past, about 300 billion years BCE.
     /// @brief The smallest possible time value.
     static TimeValue MinTime() {
       return TimeValue ( INT64_MIN,0 );
     }

     /// A constant TimeValue representing the largest time
     /// value permissible by the class. MaxTime is some point
     /// in the distant future, about 300 billion years AD.
     /// @brief The largest possible time value.
     static TimeValue MaxTime() {
       return TimeValue ( INT64_MAX,0 );
     }

     /// A constant TimeValue representing the base time,
     /// or zero time of 00:00:00 (midnight) January 1st, 2000.
     /// @brief 00:00:00 Jan 1, 2000 UTC.
     static TimeValue ZeroTime() {
       return TimeValue ( 0,0 );
     }

     /// A constant TimeValue for the Posix base time which is
     /// 00:00:00 (midnight) January 1st, 1970.
     /// @brief 00:00:00 Jan 1, 1970 UTC.
     static TimeValue PosixZeroTime() {
       return TimeValue ( PosixZeroTimeSeconds,0 );
     }

     /// A constant TimeValue for the Win32 base time which is
     /// 00:00:00 (midnight) January 1st, 1601.
     /// @brief 00:00:00 Jan 1, 1601 UTC.
     static TimeValue Win32ZeroTime() {
       return TimeValue ( Win32ZeroTimeSeconds,0 );
     }

   /// @}
   /// @name Types
   /// @{
   public:
     typedef int64_t SecondsType;    ///< Type used for representing seconds.
     typedef int32_t NanoSecondsType;///< Type used for representing nanoseconds.

     enum TimeConversions {
       NANOSECONDS_PER_SECOND = 1000000000,  ///< One Billion
       MICROSECONDS_PER_SECOND = 1000000,    ///< One Million
       MILLISECONDS_PER_SECOND = 1000,       ///< One Thousand
       NANOSECONDS_PER_MICROSECOND = 1000,   ///< One Thousand
       NANOSECONDS_PER_MILLISECOND = 1000000,///< One Million
       NANOSECONDS_PER_WIN32_TICK = 100      ///< Win32 tick is 10^7 Hz (10ns)
     };

   /// @}
   /// @name Constructors
   /// @{
   public:
     /// \brief Default construct a time value, initializing to ZeroTime.
     TimeValue() : seconds_(0), nanos_(0) {}

     /// Caller provides the exact value in seconds and nanoseconds. The
     /// \p nanos argument defaults to zero for convenience.
     /// @brief Explicit constructor
     explicit TimeValue (SecondsType seconds, NanoSecondsType nanos = 0)
       : seconds_( seconds ), nanos_( nanos ) { this->normalize(); }

     /// Caller provides the exact value as a double in seconds with the
     /// fractional part representing nanoseconds.
     /// @brief Double Constructor.
     explicit TimeValue( double new_time )
       : seconds_( 0 ) , nanos_ ( 0 ) {
       SecondsType integer_part = static_cast<SecondsType>( new_time );
       seconds_ = integer_part;
       nanos_ = static_cast<NanoSecondsType>( (new_time -
                static_cast<double>(integer_part)) * NANOSECONDS_PER_SECOND );
       this->normalize();
     }

     /// This is a static constructor that returns a TimeValue that represents
     /// the current time.
     /// @brief Creates a TimeValue with the current time (UTC).
     static TimeValue now();

   /// @}
   /// @name Operators
   /// @{
   public:
     /// Add \p that to \p this.
     /// @returns this
     /// @brief Incrementing assignment operator.
     TimeValue& operator += (const TimeValue& that ) {
       this->seconds_ += that.seconds_  ;
       this->nanos_ += that.nanos_ ;
       this->normalize();
       return *this;
     }

     /// Subtract \p that from \p this.
     /// @returns this
     /// @brief Decrementing assignment operator.
     TimeValue& operator -= (const TimeValue &that ) {
       this->seconds_ -= that.seconds_ ;
       this->nanos_ -= that.nanos_ ;
       this->normalize();
       return *this;
     }

     /// Determine if \p this is less than \p that.
     /// @returns True iff *this < that.
     /// @brief True if this < that.
     int operator < (const TimeValue &that) const { return that > *this; }

     /// Determine if \p this is greather than \p that.
     /// @returns True iff *this > that.
     /// @brief True if this > that.
     int operator > (const TimeValue &that) const {
       if ( this->seconds_ > that.seconds_ ) {
           return 1;
       } else if ( this->seconds_ == that.seconds_ ) {
           if ( this->nanos_ > that.nanos_ ) return 1;
       }
       return 0;
     }

     /// Determine if \p this is less than or equal to \p that.
     /// @returns True iff *this <= that.
     /// @brief True if this <= that.
     int operator <= (const TimeValue &that) const { return that >= *this; }

     /// Determine if \p this is greater than or equal to \p that.
     /// @returns True iff *this >= that.
     int operator >= (const TimeValue &that) const {
       if ( this->seconds_ > that.seconds_ ) {
           return 1;
       } else if ( this->seconds_ == that.seconds_ ) {
           if ( this->nanos_ >= that.nanos_ ) return 1;
       }
       return 0;
     }

     /// Determines if two TimeValue objects represent the same moment in time.
     /// @returns True iff *this == that.
     int operator == (const TimeValue &that) const {
       return (this->seconds_ == that.seconds_) &&
              (this->nanos_ == that.nanos_);
     }

     /// Determines if two TimeValue objects represent times that are not the
     /// same.
     /// @returns True iff *this != that.
     int operator != (const TimeValue &that) const { return !(*this == that); }

     /// Adds two TimeValue objects together.
     /// @returns The sum of the two operands as a new TimeValue
     /// @brief Addition operator.
     friend TimeValue operator + (const TimeValue &tv1, const TimeValue &tv2);

     /// Subtracts two TimeValue objects.
     /// @returns The difference of the two operands as a new TimeValue
     /// @brief Subtraction operator.
     friend TimeValue operator - (const TimeValue &tv1, const TimeValue &tv2);

   /// @}
   /// @name Accessors
   /// @{
   public:

     /// Returns only the seconds component of the TimeValue. The nanoseconds
     /// portion is ignored. No rounding is performed.
     /// @brief Retrieve the seconds component
     SecondsType seconds() const { return seconds_; }

     /// Returns only the nanoseconds component of the TimeValue. The seconds
     /// portion is ignored.
     /// @brief Retrieve the nanoseconds component.
     NanoSecondsType nanoseconds() const { return nanos_; }

     /// Returns only the fractional portion of the TimeValue rounded down to the
     /// nearest microsecond (divide by one thousand).
     /// @brief Retrieve the fractional part as microseconds;
     uint32_t microseconds() const {
       return nanos_ / NANOSECONDS_PER_MICROSECOND;
     }

     /// Returns only the fractional portion of the TimeValue rounded down to the
     /// nearest millisecond (divide by one million).
     /// @brief Retrieve the fractional part as milliseconds;
     uint32_t milliseconds() const {
       return nanos_ / NANOSECONDS_PER_MILLISECOND;
     }

     /// Returns the TimeValue as a number of microseconds. Note that the value
     /// returned can overflow because the range of a uint64_t is smaller than
     /// the range of a TimeValue. Nevertheless, this is useful on some operating
     /// systems and is therefore provided.
     /// @brief Convert to a number of microseconds (can overflow)
     uint64_t usec() const {
       return seconds_ * MICROSECONDS_PER_SECOND +
              ( nanos_ / NANOSECONDS_PER_MICROSECOND );
     }

     /// Returns the TimeValue as a number of milliseconds. Note that the value
     /// returned can overflow because the range of a uint64_t is smaller than
     /// the range of a TimeValue. Nevertheless, this is useful on some operating
     /// systems and is therefore provided.
     /// @brief Convert to a number of milliseconds (can overflow)
     uint64_t msec() const {
       return seconds_ * MILLISECONDS_PER_SECOND +
              ( nanos_ / NANOSECONDS_PER_MILLISECOND );
     }

     /// Converts the TimeValue into the corresponding number of seconds
     /// since the epoch (00:00:00 Jan 1,1970).
     uint64_t toEpochTime() const {
       return seconds_ - PosixZeroTimeSeconds;
     }

     /// Converts the TimeValue into the corresponding number of "ticks" for
     /// Win32 platforms, correcting for the difference in Win32 zero time.
     /// @brief Convert to Win32's FILETIME
     /// (100ns intervals since 00:00:00 Jan 1, 1601 UTC)
     uint64_t toWin32Time() const {
       uint64_t result = (uint64_t)10000000 * (seconds_ - Win32ZeroTimeSeconds);
       result += nanos_ / NANOSECONDS_PER_WIN32_TICK;
       return result;
     }

     /// Provides the seconds and nanoseconds as results in its arguments after
     /// correction for the Posix zero time.
     /// @brief Convert to timespec time (ala POSIX.1b)
     void getTimespecTime( uint64_t& seconds, uint32_t& nanos ) const {
       seconds = seconds_ - PosixZeroTimeSeconds;
       nanos = nanos_;
     }

     /// Provides conversion of the TimeValue into a readable time & date.
     /// @returns std::string containing the readable time value
     /// @brief Convert time to a string.
     std::string str() const;

   /// @}
   /// @name Mutators
   /// @{
   public:
     /// The seconds component of the TimeValue is set to \p sec without
     /// modifying the nanoseconds part.  This is useful for whole second
     /// arithmetic.
     /// @brief Set the seconds component.
     void seconds (SecondsType sec ) {
       this->seconds_ = sec;
       this->normalize();
     }

     /// The nanoseconds component of the TimeValue is set to \p nanos without
     /// modifying the seconds part. This is useful for basic computations
     /// involving just the nanoseconds portion. Note that the TimeValue will be
     /// normalized after this call so that the fractional (nanoseconds) portion
     /// will have the smallest equivalent value.
     /// @brief Set the nanoseconds component using a number of nanoseconds.
     void nanoseconds ( NanoSecondsType nanos ) {
       this->nanos_ = nanos;
       this->normalize();
     }

     /// The seconds component remains unchanged.
     /// @brief Set the nanoseconds component using a number of microseconds.
     void microseconds ( int32_t micros ) {
       this->nanos_ = micros * NANOSECONDS_PER_MICROSECOND;
       this->normalize();
     }

     /// The seconds component remains unchanged.
     /// @brief Set the nanoseconds component using a number of milliseconds.
     void milliseconds ( int32_t millis ) {
       this->nanos_ = millis * NANOSECONDS_PER_MILLISECOND;
       this->normalize();
     }

     /// @brief Converts from microsecond format to TimeValue format
     void usec( int64_t microseconds ) {
       this->seconds_ = microseconds / MICROSECONDS_PER_SECOND;
       this->nanos_ = NanoSecondsType(microseconds % MICROSECONDS_PER_SECOND) *
         NANOSECONDS_PER_MICROSECOND;
       this->normalize();
     }

     /// @brief Converts from millisecond format to TimeValue format
     void msec( int64_t milliseconds ) {
       this->seconds_ = milliseconds / MILLISECONDS_PER_SECOND;
       this->nanos_ = NanoSecondsType(milliseconds % MILLISECONDS_PER_SECOND) *
         NANOSECONDS_PER_MILLISECOND;
       this->normalize();
     }

     /// Converts the \p seconds argument from PosixTime to the corresponding
     /// TimeValue and assigns that value to \p this.
     /// @brief Convert seconds form PosixTime to TimeValue
     void fromEpochTime( SecondsType seconds ) {
       seconds_ = seconds + PosixZeroTimeSeconds;
       nanos_ = 0;
       this->normalize();
     }

     /// Converts the \p win32Time argument from Windows FILETIME to the
     /// corresponding TimeValue and assigns that value to \p this.
     /// @brief Convert seconds form Windows FILETIME to TimeValue
     void fromWin32Time( uint64_t win32Time ) {
       this->seconds_ = win32Time / 10000000 + Win32ZeroTimeSeconds;
       this->nanos_ = NanoSecondsType(win32Time  % 10000000) * 100;
     }

   /// @}
   /// @name Implementation
   /// @{
   private:
     /// This causes the values to be represented so that the fractional
     /// part is minimized, possibly incrementing the seconds part.
     /// @brief Normalize to canonical form.
     void normalize();

   /// @}
   /// @name Data
   /// @{
   private:
     /// Store the values as a <timeval>.
     SecondsType      seconds_;///< Stores the seconds part of the TimeVal
     NanoSecondsType  nanos_;  ///< Stores the nanoseconds part of the TimeVal

     static const SecondsType PosixZeroTimeSeconds;
     static const SecondsType Win32ZeroTimeSeconds;
   /// @}

   };

 inline TimeValue operator + (const TimeValue &tv1, const TimeValue &tv2) {
   TimeValue sum (tv1.seconds_ + tv2.seconds_, tv1.nanos_ + tv2.nanos_);
   sum.normalize ();
   return sum;
 }

 inline TimeValue operator - (const TimeValue &tv1, const TimeValue &tv2) {
   TimeValue difference (tv1.seconds_ - tv2.seconds_, tv1.nanos_ - tv2.nanos_ );
   difference.normalize ();
   return difference;
 }

 }
 }

 #endif
	//===-- TimeValue.h - Declare OS TimeValue Concept --------------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This header file declares the operating system TimeValue concept.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_SUPPORT_TIMEVALUE_H
	#define LLVM_SUPPORT_TIMEVALUE_H

	#include "llvm/Support/DataTypes.h"
	#include <string>

	namespace llvm {
	namespace sys {
	/// This class is used where a precise fixed point in time is required. The
	/// range of TimeValue spans many hundreds of billions of years both past and
	/// present. The precision of TimeValue is to the nanosecond. However, the
	/// actual precision of its values will be determined by the resolution of
	/// the system clock. The TimeValue class is used in conjunction with several
	/// other lib/System interfaces to specify the time at which a call should
	/// timeout, etc.
	/// @since 1.4
	/// @brief Provides an abstraction for a fixed point in time.
	class TimeValue {

	/// @name Constants
	/// @{
	public:

	/// A constant TimeValue representing the smallest time
	/// value permissible by the class. MinTime is some point
	/// in the distant past, about 300 billion years BCE.
	/// @brief The smallest possible time value.
	static TimeValue MinTime() {
	return TimeValue ( INT64_MIN,0 );
	}

	/// A constant TimeValue representing the largest time
	/// value permissible by the class. MaxTime is some point
	/// in the distant future, about 300 billion years AD.
	/// @brief The largest possible time value.
	static TimeValue MaxTime() {
	return TimeValue ( INT64_MAX,0 );
	}

	/// A constant TimeValue representing the base time,
	/// or zero time of 00:00:00 (midnight) January 1st, 2000.
	/// @brief 00:00:00 Jan 1, 2000 UTC.
	static TimeValue ZeroTime() {
	return TimeValue ( 0,0 );
	}

	/// A constant TimeValue for the Posix base time which is
	/// 00:00:00 (midnight) January 1st, 1970.
	/// @brief 00:00:00 Jan 1, 1970 UTC.
	static TimeValue PosixZeroTime() {
	return TimeValue ( PosixZeroTimeSeconds,0 );
	}

	/// A constant TimeValue for the Win32 base time which is
	/// 00:00:00 (midnight) January 1st, 1601.
	/// @brief 00:00:00 Jan 1, 1601 UTC.
	static TimeValue Win32ZeroTime() {
	return TimeValue ( Win32ZeroTimeSeconds,0 );
	}

	/// @}
	/// @name Types
	/// @{
	public:
	typedef int64_t SecondsType; ///< Type used for representing seconds.
	typedef int32_t NanoSecondsType;///< Type used for representing nanoseconds.

	enum TimeConversions {
	NANOSECONDS_PER_SECOND = 1000000000, ///< One Billion
	MICROSECONDS_PER_SECOND = 1000000, ///< One Million
	MILLISECONDS_PER_SECOND = 1000, ///< One Thousand
	NANOSECONDS_PER_MICROSECOND = 1000, ///< One Thousand
	NANOSECONDS_PER_MILLISECOND = 1000000,///< One Million
	NANOSECONDS_PER_WIN32_TICK = 100 ///< Win32 tick is 10^7 Hz (10ns)
	};

	/// @}
	/// @name Constructors
	/// @{
	public:
	/// \brief Default construct a time value, initializing to ZeroTime.
	TimeValue() : seconds_(0), nanos_(0) {}

	/// Caller provides the exact value in seconds and nanoseconds. The
	/// \p nanos argument defaults to zero for convenience.
	/// @brief Explicit constructor
	explicit TimeValue (SecondsType seconds, NanoSecondsType nanos = 0)
	: seconds_( seconds ), nanos_( nanos ) { this->normalize(); }

	/// Caller provides the exact value as a double in seconds with the
	/// fractional part representing nanoseconds.
	/// @brief Double Constructor.
	explicit TimeValue( double new_time )
	: seconds_( 0 ) , nanos_ ( 0 ) {
	SecondsType integer_part = static_cast<SecondsType>( new_time );
	seconds_ = integer_part;
	nanos_ = static_cast<NanoSecondsType>( (new_time -
	static_cast<double>(integer_part)) * NANOSECONDS_PER_SECOND );
	this->normalize();
	}

	/// This is a static constructor that returns a TimeValue that represents
	/// the current time.
	/// @brief Creates a TimeValue with the current time (UTC).
	static TimeValue now();

	/// @}
	/// @name Operators
	/// @{
	public:
	/// Add \p that to \p this.
	/// @returns this
	/// @brief Incrementing assignment operator.
	TimeValue& operator += (const TimeValue& that ) {
	this->seconds_ += that.seconds_ ;
	this->nanos_ += that.nanos_ ;
	this->normalize();
	return *this;
	}

	/// Subtract \p that from \p this.
	/// @returns this
	/// @brief Decrementing assignment operator.
	TimeValue& operator -= (const TimeValue &that ) {
	this->seconds_ -= that.seconds_ ;
	this->nanos_ -= that.nanos_ ;
	this->normalize();
	return *this;
	}

	/// Determine if \p this is less than \p that.
	/// @returns True iff *this < that.
	/// @brief True if this < that.
	int operator < (const TimeValue &that) const { return that > *this; }

	/// Determine if \p this is greather than \p that.
	/// @returns True iff *this > that.
	/// @brief True if this > that.
	int operator > (const TimeValue &that) const {
	if ( this->seconds_ > that.seconds_ ) {
	return 1;
	} else if ( this->seconds_ == that.seconds_ ) {
	if ( this->nanos_ > that.nanos_ ) return 1;
	}
	return 0;
	}

	/// Determine if \p this is less than or equal to \p that.
	/// @returns True iff *this <= that.
	/// @brief True if this <= that.
	int operator <= (const TimeValue &that) const { return that >= *this; }

	/// Determine if \p this is greater than or equal to \p that.
	/// @returns True iff *this >= that.
	int operator >= (const TimeValue &that) const {
	if ( this->seconds_ > that.seconds_ ) {
	return 1;
	} else if ( this->seconds_ == that.seconds_ ) {
	if ( this->nanos_ >= that.nanos_ ) return 1;
	}
	return 0;
	}

	/// Determines if two TimeValue objects represent the same moment in time.
	/// @returns True iff *this == that.
	int operator == (const TimeValue &that) const {
	return (this->seconds_ == that.seconds_) &&
	(this->nanos_ == that.nanos_);
	}

	/// Determines if two TimeValue objects represent times that are not the
	/// same.
	/// @returns True iff *this != that.
	int operator != (const TimeValue &that) const { return !(*this == that); }

	/// Adds two TimeValue objects together.
	/// @returns The sum of the two operands as a new TimeValue
	/// @brief Addition operator.
	friend TimeValue operator + (const TimeValue &tv1, const TimeValue &tv2);

	/// Subtracts two TimeValue objects.
	/// @returns The difference of the two operands as a new TimeValue
	/// @brief Subtraction operator.
	friend TimeValue operator - (const TimeValue &tv1, const TimeValue &tv2);

	/// @}
	/// @name Accessors
	/// @{
	public:

	/// Returns only the seconds component of the TimeValue. The nanoseconds
	/// portion is ignored. No rounding is performed.
	/// @brief Retrieve the seconds component
	SecondsType seconds() const { return seconds_; }

	/// Returns only the nanoseconds component of the TimeValue. The seconds
	/// portion is ignored.
	/// @brief Retrieve the nanoseconds component.
	NanoSecondsType nanoseconds() const { return nanos_; }

	/// Returns only the fractional portion of the TimeValue rounded down to the
	/// nearest microsecond (divide by one thousand).
	/// @brief Retrieve the fractional part as microseconds;
	uint32_t microseconds() const {
	return nanos_ / NANOSECONDS_PER_MICROSECOND;
	}

	/// Returns only the fractional portion of the TimeValue rounded down to the
	/// nearest millisecond (divide by one million).
	/// @brief Retrieve the fractional part as milliseconds;
	uint32_t milliseconds() const {
	return nanos_ / NANOSECONDS_PER_MILLISECOND;
	}

	/// Returns the TimeValue as a number of microseconds. Note that the value
	/// returned can overflow because the range of a uint64_t is smaller than
	/// the range of a TimeValue. Nevertheless, this is useful on some operating
	/// systems and is therefore provided.
	/// @brief Convert to a number of microseconds (can overflow)
	uint64_t usec() const {
	return seconds_ * MICROSECONDS_PER_SECOND +
	( nanos_ / NANOSECONDS_PER_MICROSECOND );
	}

	/// Returns the TimeValue as a number of milliseconds. Note that the value
	/// returned can overflow because the range of a uint64_t is smaller than
	/// the range of a TimeValue. Nevertheless, this is useful on some operating
	/// systems and is therefore provided.
	/// @brief Convert to a number of milliseconds (can overflow)
	uint64_t msec() const {
	return seconds_ * MILLISECONDS_PER_SECOND +
	( nanos_ / NANOSECONDS_PER_MILLISECOND );
	}

	/// Converts the TimeValue into the corresponding number of seconds
	/// since the epoch (00:00:00 Jan 1,1970).
	uint64_t toEpochTime() const {
	return seconds_ - PosixZeroTimeSeconds;
	}

	/// Converts the TimeValue into the corresponding number of "ticks" for
	/// Win32 platforms, correcting for the difference in Win32 zero time.
	/// @brief Convert to Win32's FILETIME
	/// (100ns intervals since 00:00:00 Jan 1, 1601 UTC)
	uint64_t toWin32Time() const {
	uint64_t result = (uint64_t)10000000 * (seconds_ - Win32ZeroTimeSeconds);
	result += nanos_ / NANOSECONDS_PER_WIN32_TICK;
	return result;
	}

	/// Provides the seconds and nanoseconds as results in its arguments after
	/// correction for the Posix zero time.
	/// @brief Convert to timespec time (ala POSIX.1b)
	void getTimespecTime( uint64_t& seconds, uint32_t& nanos ) const {
	seconds = seconds_ - PosixZeroTimeSeconds;
	nanos = nanos_;
	}

	/// Provides conversion of the TimeValue into a readable time & date.
	/// @returns std::string containing the readable time value
	/// @brief Convert time to a string.
	std::string str() const;

	/// @}
	/// @name Mutators
	/// @{
	public:
	/// The seconds component of the TimeValue is set to \p sec without
	/// modifying the nanoseconds part. This is useful for whole second
	/// arithmetic.
	/// @brief Set the seconds component.
	void seconds (SecondsType sec ) {
	this->seconds_ = sec;
	this->normalize();
	}

	/// The nanoseconds component of the TimeValue is set to \p nanos without
	/// modifying the seconds part. This is useful for basic computations
	/// involving just the nanoseconds portion. Note that the TimeValue will be
	/// normalized after this call so that the fractional (nanoseconds) portion
	/// will have the smallest equivalent value.
	/// @brief Set the nanoseconds component using a number of nanoseconds.
	void nanoseconds ( NanoSecondsType nanos ) {
	this->nanos_ = nanos;
	this->normalize();
	}

	/// The seconds component remains unchanged.
	/// @brief Set the nanoseconds component using a number of microseconds.
	void microseconds ( int32_t micros ) {
	this->nanos_ = micros * NANOSECONDS_PER_MICROSECOND;
	this->normalize();
	}

	/// The seconds component remains unchanged.
	/// @brief Set the nanoseconds component using a number of milliseconds.
	void milliseconds ( int32_t millis ) {
	this->nanos_ = millis * NANOSECONDS_PER_MILLISECOND;
	this->normalize();
	}

	/// @brief Converts from microsecond format to TimeValue format
	void usec( int64_t microseconds ) {
	this->seconds_ = microseconds / MICROSECONDS_PER_SECOND;
	this->nanos_ = NanoSecondsType(microseconds % MICROSECONDS_PER_SECOND) *
	NANOSECONDS_PER_MICROSECOND;
	this->normalize();
	}

	/// @brief Converts from millisecond format to TimeValue format
	void msec( int64_t milliseconds ) {
	this->seconds_ = milliseconds / MILLISECONDS_PER_SECOND;
	this->nanos_ = NanoSecondsType(milliseconds % MILLISECONDS_PER_SECOND) *
	NANOSECONDS_PER_MILLISECOND;
	this->normalize();
	}

	/// Converts the \p seconds argument from PosixTime to the corresponding
	/// TimeValue and assigns that value to \p this.
	/// @brief Convert seconds form PosixTime to TimeValue
	void fromEpochTime( SecondsType seconds ) {
	seconds_ = seconds + PosixZeroTimeSeconds;
	nanos_ = 0;
	this->normalize();
	}

	/// Converts the \p win32Time argument from Windows FILETIME to the
	/// corresponding TimeValue and assigns that value to \p this.
	/// @brief Convert seconds form Windows FILETIME to TimeValue
	void fromWin32Time( uint64_t win32Time ) {
	this->seconds_ = win32Time / 10000000 + Win32ZeroTimeSeconds;
	this->nanos_ = NanoSecondsType(win32Time % 10000000) * 100;
	}

	/// @}
	/// @name Implementation
	/// @{
	private:
	/// This causes the values to be represented so that the fractional
	/// part is minimized, possibly incrementing the seconds part.
	/// @brief Normalize to canonical form.
	void normalize();

	/// @}
	/// @name Data
	/// @{
	private:
	/// Store the values as a <timeval>.
	SecondsType seconds_;///< Stores the seconds part of the TimeVal
	NanoSecondsType nanos_; ///< Stores the nanoseconds part of the TimeVal

	static const SecondsType PosixZeroTimeSeconds;
	static const SecondsType Win32ZeroTimeSeconds;
	/// @}

	};

	inline TimeValue operator + (const TimeValue &tv1, const TimeValue &tv2) {
	TimeValue sum (tv1.seconds_ + tv2.seconds_, tv1.nanos_ + tv2.nanos_);
	sum.normalize ();
	return sum;
	}

	inline TimeValue operator - (const TimeValue &tv1, const TimeValue &tv2) {
	TimeValue difference (tv1.seconds_ - tv2.seconds_, tv1.nanos_ - tv2.nanos_ );
	difference.normalize ();
	return difference;
	}

	}
	}

	#endif