SYS_Time.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        SYS_Time.h (SYS Library, C++)
 *
 * COMMENTS:    Platform-independent time structures
 */

#ifndef __SYS_TIME_H_INCLUDED__
#define __SYS_TIME_H_INCLUDED__

#include "SYS_API.h"
#include "SYS_Types.h"
#include <time.h>

#ifdef WIN32
struct SYS_TimeVal
{
    exint   tv_sec;         /* seconds */
    exint   tv_usec;        /* and microseconds */
};

#define timegm _mkgmtime

#else

#include <sys/time.h>

typedef struct timeval SYS_TimeVal;

#endif

/// SYSgettimeofday() fills in tval with the "current" time, which cannot be
/// given any particular meaning. These values are only useful for comparing
/// against each other.
SYS_API int SYSgettimeofday(SYS_TimeVal *tval);

/// Return a number of milliseconds since the process started. This function
/// will wrap values every 50 days or so.
SYS_API time_t  SYSclock();

/// Return the number of seconds since some arbitrary start time as a real
/// number.  Returns -1 if there was an error computing the time.
SYS_API fpreal  SYStime();

/// Return the number of seconds expressed in the given time value.
SYS_API fpreal  SYStime(const SYS_TimeVal &tval);

/// Return the system resource usage times (user and system) for the current
/// process.
SYS_API void    SYSrusage(SYS_TimeVal &user, SYS_TimeVal &sys);

/// Return the number of seconds (with floating point precision) between the
/// start and end times. The end time should be later than the start time.
inline fpreal64
SYStimeDiff(const SYS_TimeVal &end, const SYS_TimeVal &start)
{
    return fpreal64(end.tv_sec - start.tv_sec) +
           1.0e-6 * (end.tv_usec - start.tv_usec);
}

#endif // __SYS_TIME_H_INCLUDED__