source: NonGTP/Boost/boost/timer.hpp @ 857

Revision 857, 2.7 KB checked in by igarcia, 19 years ago (diff)
Line 
1//  boost timer.hpp header file  ---------------------------------------------//
2
3//  Copyright Beman Dawes 1994-99.  Distributed under the Boost
4//  Software License, Version 1.0. (See accompanying file
5//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6
7//  See http://www.boost.org/libs/timer for documentation.
8
9//  Revision History
10//  01 Apr 01  Modified to use new <boost/limits.hpp> header. (JMaddock)
11//  12 Jan 01  Change to inline implementation to allow use without library
12//             builds. See docs for more rationale. (Beman Dawes)
13//  25 Sep 99  elapsed_max() and elapsed_min() added (John Maddock)
14//  16 Jul 99  Second beta
15//   6 Jul 99  Initial boost version
16
17#ifndef BOOST_TIMER_HPP
18#define BOOST_TIMER_HPP
19
20#include <boost/config.hpp>
21#include <ctime>
22#include <boost/limits.hpp>
23
24# ifdef BOOST_NO_STDC_NAMESPACE
25    namespace std { using ::clock_t; using ::clock; }
26# endif
27
28
29namespace boost {
30
31//  timer  -------------------------------------------------------------------//
32
33//  A timer object measures elapsed time.
34
35//  It is recommended that implementations measure wall clock rather than CPU
36//  time since the intended use is performance measurement on systems where
37//  total elapsed time is more important than just process or CPU time.
38
39//  Warnings: The maximum measurable elapsed time may well be only 596.5+ hours
40//  due to implementation limitations.  The accuracy of timings depends on the
41//  accuracy of timing information provided by the underlying platform, and
42//  this varies a great deal from platform to platform.
43
44class timer
45{
46 public:
47         timer() { _start_time = std::clock(); } // postcondition: elapsed()==0
48//         timer( const timer& src );      // post: elapsed()==src.elapsed()
49//        ~timer(){}
50//  timer& operator=( const timer& src );  // post: elapsed()==src.elapsed()
51  void   restart() { _start_time = std::clock(); } // post: elapsed()==0
52  double elapsed() const                  // return elapsed time in seconds
53    { return  double(std::clock() - _start_time) / CLOCKS_PER_SEC; }
54
55  double elapsed_max() const   // return estimated maximum value for elapsed()
56  // Portability warning: elapsed_max() may return too high a value on systems
57  // where std::clock_t overflows or resets at surprising values.
58  {
59    return (double((std::numeric_limits<std::clock_t>::max)())
60       - double(_start_time)) / double(CLOCKS_PER_SEC);
61  }
62
63  double elapsed_min() const            // return minimum value for elapsed()
64   { return double(1)/double(CLOCKS_PER_SEC); }
65
66 private:
67  std::clock_t _start_time;
68}; // timer
69
70} // namespace boost
71
72#endif  // BOOST_TIMER_HPP
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