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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // Time represents an absolute point in coordinated universal time (UTC), | 5 // Time represents an absolute point in coordinated universal time (UTC), |
6 // internally represented as microseconds (s/1,000,000) since the Windows epoch | 6 // internally represented as microseconds (s/1,000,000) since the Windows epoch |
7 // (1601-01-01 00:00:00 UTC) (See http://crbug.com/14734). System-dependent | 7 // (1601-01-01 00:00:00 UTC) (See http://crbug.com/14734). System-dependent |
8 // clock interface routines are defined in time_PLATFORM.cc. | 8 // clock interface routines are defined in time_PLATFORM.cc. |
9 // | 9 // |
10 // TimeDelta represents a duration of time, internally represented in | 10 // TimeDelta represents a duration of time, internally represented in |
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632 #if defined(OS_WIN) | 632 #if defined(OS_WIN) |
633 // Get the absolute value of QPC time drift. For testing. | 633 // Get the absolute value of QPC time drift. For testing. |
634 static int64 GetQPCDriftMicroseconds(); | 634 static int64 GetQPCDriftMicroseconds(); |
635 | 635 |
636 static TimeTicks FromQPCValue(LONGLONG qpc_value); | 636 static TimeTicks FromQPCValue(LONGLONG qpc_value); |
637 | 637 |
638 // Returns true if the high resolution clock is working on this system. | 638 // Returns true if the high resolution clock is working on this system. |
639 // This is only for testing. | 639 // This is only for testing. |
640 static bool IsHighResClockWorking(); | 640 static bool IsHighResClockWorking(); |
641 | 641 |
642 // Enable high resolution time for TimeTicks::Now(). This function will | |
643 // test for the availability of a working implementation of | |
644 // QueryPerformanceCounter(). If one is not available, this function does | |
645 // nothing and the resolution of Now() remains 1ms. Otherwise, all future | |
646 // calls to TimeTicks::Now() will have the higher resolution provided by QPC. | |
647 // Returns true if high resolution time was successfully enabled. | |
648 static bool SetNowIsHighResNowIfSupported(); | |
649 | |
650 // Returns a time value that is NOT rollover protected. | 642 // Returns a time value that is NOT rollover protected. |
651 static TimeTicks UnprotectedNow(); | 643 static TimeTicks UnprotectedNow(); |
652 #endif | 644 #endif |
653 | 645 |
654 // Returns true if this object has not been initialized. | 646 // Returns true if this object has not been initialized. |
655 bool is_null() const { | 647 bool is_null() const { |
656 return ticks_ == 0; | 648 return ticks_ == 0; |
657 } | 649 } |
658 | 650 |
659 // Converts an integer value representing TimeTicks to a class. This is used | 651 // Converts an integer value representing TimeTicks to a class. This is used |
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743 #endif | 735 #endif |
744 }; | 736 }; |
745 | 737 |
746 inline TimeTicks TimeDelta::operator+(TimeTicks t) const { | 738 inline TimeTicks TimeDelta::operator+(TimeTicks t) const { |
747 return TimeTicks(t.ticks_ + delta_); | 739 return TimeTicks(t.ticks_ + delta_); |
748 } | 740 } |
749 | 741 |
750 } // namespace base | 742 } // namespace base |
751 | 743 |
752 #endif // BASE_TIME_TIME_H_ | 744 #endif // BASE_TIME_TIME_H_ |
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