mirror of https://github.com/CGAL/cgal
110 lines
3.6 KiB
C++
110 lines
3.6 KiB
C++
// Copyright (c) 1997 Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
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// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
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// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Lutz Kettner <kettner@inf.ethz.ch>
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// Matthias Baesken <baesken@informatik.uni-halle.de>
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#include <CGAL/Real_timer.h>
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#if defined (_MSC_VER)
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# include <sys/timeb.h>
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# include <sys/types.h>
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#elif defined (__MINGW32__)
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# include <sys/timeb.h>
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# include <sys/types.h>
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#else
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// If none of the above PC compilers, use POSIX fct. gettimeofday()
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# include <sys/time.h>
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#endif
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CGAL_BEGIN_NAMESPACE
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// Static member variable for Real_timer
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// =====================================
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bool Real_timer::m_failed = false;
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// Member functions for Real_timer
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// =====================================
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double Real_timer::get_real_time() const {
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// Depends on the operating system.
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// Returns a (weakly ;-) monotone increasing time in seconds (with
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// possible wrap-around in case of overflow, see max()), or 0.0
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// if the system call for the time failed. If the system call
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// failed the static flag 'm_failed' is set and can be used
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// by the caller.
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#if defined(_MSC_VER)
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struct _timeb t;
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_ftime(&t);
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return double(t.time) + double(t.millitm) / 1000.0;
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#elif defined (__MINGW32__)
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struct timeb t;
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ftime(&t);
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return double(t.time) + double(t.millitm) / 1000.0;
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#else // ! _MSC_VER && ! __MINGW32__//
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struct timeval t;
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int ret = gettimeofday( &t, NULL);
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CGAL_warning_msg( ret == 0, "Call to gettimeofday() in class "
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"CGAL::Real_timer failed - timings will be 0.");
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if ( ret == 0) {
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return double(t.tv_sec) + double(t.tv_usec) / 1000000;
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}
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m_failed = true;
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return 0.0;
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#endif // ! _MSC_VER && ! __MINGW32__//
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}
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double Real_timer::compute_precision() const {
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// Computes timer precision in seconds dynamically. Note that
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// the timer system call is probably non-trivial and will show
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// up in this time here (probably for one call). But that is just
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// fine that the call to the timer itself if reported as noise
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// in the precision.
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double min_res = DBL_MAX;
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for ( int i = 0; i < 5; ++i) {
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double current = get_real_time();
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if ( m_failed)
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return -1.0;
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double next = get_real_time();
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while ( current >= next) { // wait until timer increases
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next = get_real_time();
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if ( m_failed)
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return -1.0;
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}
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// Get the minimum timing difference of all runs.
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if ( min_res > next - current)
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min_res = next - current;
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}
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return min_res;
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}
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double Real_timer::precision() const {
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// computes precision upon first call
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// returns -1.0 if timer system call fails.
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static double prec = compute_precision();
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return prec;
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}
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CGAL_END_NAMESPACE
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