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73 lines
2.6 KiB
C++
73 lines
2.6 KiB
C++
// boost timer.hpp header file ---------------------------------------------//
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// Copyright Beman Dawes 1994-99. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// See http://www.boost.org/libs/timer for documentation.
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// Revision History
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// 01 Apr 01 Modified to use new <boost/limits.hpp> header. (JMaddock)
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// 12 Jan 01 Change to inline implementation to allow use without library
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// builds. See docs for more rationale. (Beman Dawes)
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// 25 Sep 99 elapsed_max() and elapsed_min() added (John Maddock)
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// 16 Jul 99 Second beta
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// 6 Jul 99 Initial boost version
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#ifndef BOOST_TIMER_HPP
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#define BOOST_TIMER_HPP
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#include <boost/config.hpp>
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#include <ctime>
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#include <boost/limits.hpp>
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# ifdef BOOST_NO_STDC_NAMESPACE
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namespace std { using ::clock_t; using ::clock; }
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# endif
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namespace boost {
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// timer -------------------------------------------------------------------//
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// A timer object measures elapsed time.
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// It is recommended that implementations measure wall clock rather than CPU
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// time since the intended use is performance measurement on systems where
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// total elapsed time is more important than just process or CPU time.
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// Warnings: The maximum measurable elapsed time may well be only 596.5+ hours
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// due to implementation limitations. The accuracy of timings depends on the
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// accuracy of timing information provided by the underlying platform, and
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// this varies a great deal from platform to platform.
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class timer
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{
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public:
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timer() { _start_time = std::clock(); } // postcondition: elapsed()==0
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// timer( const timer& src ); // post: elapsed()==src.elapsed()
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// ~timer(){}
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// timer& operator=( const timer& src ); // post: elapsed()==src.elapsed()
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void restart() { _start_time = std::clock(); } // post: elapsed()==0
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double elapsed() const // return elapsed time in seconds
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{ return double(std::clock() - _start_time) / CLOCKS_PER_SEC; }
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double elapsed_max() const // return estimated maximum value for elapsed()
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// Portability warning: elapsed_max() may return too high a value on systems
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// where std::clock_t overflows or resets at surprising values.
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{
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return (double((std::numeric_limits<std::clock_t>::max)())
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- double(_start_time)) / double(CLOCKS_PER_SEC);
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}
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double elapsed_min() const // return minimum value for elapsed()
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{ return double(1)/double(CLOCKS_PER_SEC); }
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private:
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std::clock_t _start_time;
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}; // timer
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} // namespace boost
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#endif // BOOST_TIMER_HPP
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