do i just want to be doing something like:
t1 = clock();
t2 = clock();
while ((t2-t1)/CLOCKS_PER_SEC<.01) t2 = clock();
or is there a more elegant way of pausing for a set amount of time?
pausing or waiting in c
- Thread starter bigalt
- Start date
do i just want to be doing something like:
t1 = clock();
t2 = clock();
while ((t2-t1)/CLOCKS_PER_SEC<.01) t2 = clock();
or is there a more elegant way of pausing for a set amount of time?
Depends on the OS. You might be able to sleep() or in Windows you can set a timer which fires a message.
- Oct 30, 2000
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nope. not part of the standard, but sleep(int seconds) is common in unix (unistd.h)
in windows, Sleep(millisecs) serves a similar purpose (windows.h)
POSIX specifies nanosleep() for fine-grained delays. Probably you can use usleep(), which is simpler to use than nanosleep(), but is defined (and differently at that) by BSD 4.3 and SUSv2.
sleep() is POSIX too, but it only works on whole seconds.
clock() only measures processor time for the process it runs under. Or at least that's what the spec says. Still, it's the only ANSI function that measures with the precision you look like you want. Everything else is a syscall.
Timers appear to be the Windows option. I wouldn't know if any of the above work for it (probably not).
sleep() is POSIX too, but it only works on whole seconds.
clock() only measures processor time for the process it runs under. Or at least that's what the spec says. Still, it's the only ANSI function that measures with the precision you look like you want. Everything else is a syscall.
Timers appear to be the Windows option. I wouldn't know if any of the above work for it (probably not).
well the sleep() function doesn't seem to fly with my visual c 6.0 under windows.h.
if the clock function only counts for the current process that might be kind of awkward considering I have to have multiple threads.
Maybe someone can suggest a better way to do this:
We've got a PC running windows connected to a robotic arm which wants 6 variables every 12 ms (more or less). It also wants a UDP connection kept alive the whole time (hence the separate thread.
These variables are changes in position and angle. Unfortunately the experiment we're running can only figure out these numbers ever 1 second or so.
So what my current plan is, keep this UDP process running, and have it feed off a global set of variables. I want it to send every 10 ms or so and then reset the variables to zero, so it sends that change once and no more.
I'd rather have it miss the variable and have to repeat the step a second later than have it overshoot. Neither is that big a deal, so precision isn't too much of an issue.
So my thought was to have my send loop delay about 10 ms each time. Sound reasonable?
if the clock function only counts for the current process that might be kind of awkward considering I have to have multiple threads.
Maybe someone can suggest a better way to do this:
We've got a PC running windows connected to a robotic arm which wants 6 variables every 12 ms (more or less). It also wants a UDP connection kept alive the whole time (hence the separate thread.
These variables are changes in position and angle. Unfortunately the experiment we're running can only figure out these numbers ever 1 second or so.
So what my current plan is, keep this UDP process running, and have it feed off a global set of variables. I want it to send every 10 ms or so and then reset the variables to zero, so it sends that change once and no more.
I'd rather have it miss the variable and have to repeat the step a second later than have it overshoot. Neither is that big a deal, so precision isn't too much of an issue.
So my thought was to have my send loop delay about 10 ms each time. Sound reasonable?
Sounds like you need to use this:
The SetTimer function creates a timer with the specified time-out value.
UINT_PTR SetTimer(
HWND hWnd, // handle to window
UINT_PTR nIDEvent, // timer identifier
UINT uElapse, // time-out value
TIMERPROC lpTimerFunc // timer procedure
) ;
as essentially a 10 ms "hearbeat" interrupt generator then have a message handler for the timer messages. See details at MSDN or in your books online
The SetTimer function creates a timer with the specified time-out value.
UINT_PTR SetTimer(
HWND hWnd, // handle to window
UINT_PTR nIDEvent, // timer identifier
UINT uElapse, // time-out value
TIMERPROC lpTimerFunc // timer procedure
) ;
as essentially a 10 ms "hearbeat" interrupt generator then have a message handler for the timer messages. See details at MSDN or in your books online
I forgot to mention that I'm more of a recycler than a coder, so I'm working off of code which I don't fully understand.
The timer looks like generally what I want to do, but it would take some rewriting. Basically any for/if/whiles that operate on the timer would need to be transferred to a function which would serve as my TimerFunc? and if I have no idea what a window is, how would I treat that handle?
Or up another tree, if neither my windows.h or my winuser.h seem to have the sleep function, what's the best remedy for that? Can I just download one from somewhere else with no problems?
edit: grr... i can't find settimer either. is there a place i'm supposed to update my windows.h file?
The timer looks like generally what I want to do, but it would take some rewriting. Basically any for/if/whiles that operate on the timer would need to be transferred to a function which would serve as my TimerFunc? and if I have no idea what a window is, how would I treat that handle?
Or up another tree, if neither my windows.h or my winuser.h seem to have the sleep function, what's the best remedy for that? Can I just download one from somewhere else with no problems?
edit: grr... i can't find settimer either. is there a place i'm supposed to update my windows.h file?
" Header: Declared in Winuser.h; include Windows.h." <-- The Friendly Manual (Books Online or MSDN)
If you don't know the Windows event-driven model where "messages" sent to "windows" control program flow, and don't want to work through Petzold's Programming Windows to learn it, then just keeping your current polling loops might be the way to go.
sorry I'm so slow, and thanks for your time
The windows.h I have doesn't seem to have the sleep included though.
That is, I have done an #include <windows.h> (with and without the capital)
and the compiler still doesn't recognize sleep(.01);
edit: omfg I'm retarded, it was Sleep() and not sleep()
re-edit: It does take some practice to be able to digest the friendly manual! thanks again!
Again in The Friendly Manual:
"VOID Sleep(
DWORD dwMilliseconds // sleep time
) ;
...
Header: Declared in Winbase.h; include Windows.h. '
Your error could come from using _s_leep instead of _S_leep, or from using a double instead of a DWORD (which is a 32-bit int)
"VOID Sleep(
DWORD dwMilliseconds // sleep time
) ;
...
Header: Declared in Winbase.h; include Windows.h. '
Your error could come from using _s_leep instead of _S_leep, or from using a double instead of a DWORD (which is a 32-bit int)
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