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fixed check for monotony (was a no-op); added resolution check (previously guessed 1ms)

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This was SVN commit r586.
This commit is contained in:
janwas 2004-06-22 16:05:44 +00:00
parent fd701dc5d9
commit d5424bcb41
1 changed files with 13 additions and 6 deletions
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19
source/lib/timer.cpp
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@ -24,9 +24,11 @@
#include <numeric>
#include <math.h>
// wrapper over gettimeofday, instead of emulating it for Windows,
// because double return type allows higher resolution (e.g. if using TSC),
// and gettimeofday is not guaranteed to be monotonic.
// rationale for wrapping gettimeofday and clock_gettime, instead of emulating
// them where not available: allows returning higher-resolution timer values
// than their µs / ns interface, via double [seconds]. they're also not
// guaranteed to be monotonic.
double get_time()
{
@ -62,8 +64,9 @@ double get_time()
// make sure time is monotonic (never goes backwards)
static double t_last;
if(t_last != 0.0 && t < t_last)
if(t < t_last)
t = t_last;
t_last = t;
return t;
}
@ -79,8 +82,12 @@ double timer_res()
#else
// guess millisecond-class
return 1e-3;
double t0, t1, t2;
t0 = get_time();
do t1 = get_time(); while(t1 == t0);
do t2 = get_time(); while(t2 == t1);
return t2-t1;
#endif
}