clockWC.cpp

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/**
 * @file clockWC.cpp
 *    Definitions for a simple class that implements an Ansi C wall clock timer
 *     (see \ref Cantera::clockWC).
 */
/*
 * $Author: hkmoffa $
 * $Revision: 368 $
 * $Date: 2010-01-03 19:46:26 -0500 (Sun, 03 Jan 2010) $
 */
/*
 * Copywrite 2004 Sandia Corporation. Under the terms of Contract
 * DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government
 * retains certain rights in this software.
 * See file License.txt for licensing information.
 */

#include <time.h>
#include "clockWC.h"
namespace Cantera {

 
  clockWC::clockWC() :
    last_num_ticks(clock()),
    clock_rollovers(0u),
    start_ticks(0),
    inv_clocks_per_sec(1./(double)CLOCKS_PER_SEC),
    clock_width((double)(1L<<((int)sizeof(clock_t)*8-2))*4./(double)CLOCKS_PER_SEC)
  {
    start_ticks = last_num_ticks;
  }

  /*
   * Reinitialize the tick counters within the object
   */
  double clockWC::start()
  {
    start_ticks = last_num_ticks = clock();
    clock_rollovers = 0u;
    return 0.0;
  }

  /*
   *    Returns system cpu and wall clock time in seconds. This
   *    is a strictly Ansi C timer, since clock() is defined as an
   *    Ansi C function. On some machines clock() returns type
   *    unsigned long (HP) and on others (SUN) it returns type long.
   *       An attempt to recover the actual time for clocks which have
   *    rolled over is made also. However, it only works if this 
   *    function is called fairly regularily during
   *    the solution procedure.
   *
   *    clock() -> returns the time in microseconds. Division by
   *               the macro CLOCKS_PER_SEC recovers the time in seconds.
   */
  double clockWC::secondsWC()
  {
    clock_t num_ticks = clock();
    if (num_ticks < last_num_ticks) clock_rollovers++;
    double value = (num_ticks - start_ticks) * inv_clocks_per_sec;
    if (clock_rollovers) value += clock_rollovers * clock_width;
    last_num_ticks = num_ticks;
    return(value);
  }
}