How to create a Timer in C of fixed Duration [closed] - c++

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How to create a timer of 200µs in C/C++?
Just perform some task in that time and then timer reset and after every 200µs keeps performing the same task?

Answer 1

C++ has std::chrono::high_resolution_clock which may have nanoseconds precision.
...represents the clock with the smallest tick period provided by the
implementation.
Standard time functions in C aren't very precise. ~15ms error you can expect.
For waiting: Unix implementations provide usleep and nanosleep. On Windows you can use CreateWaitableTimer (example).
For current time: Unix provides clock_gettime, Windows QueryPerformanceCounter (more).
Implementing a timer class which uses these time functions shouldn't be much work but if you use a good framework probably a high resolution timer is already available.

Answer 2

Example windows code for a thread. Note that cpu usage will be 100% for the core running this thread.
/* code for a thread to run at fixed frequency */
typedef unsigned long long UI64; /* unsigned 64 bit int */
#define FREQ 5000 /* frequency */
LARGE_INTEGER liPerfFreq; /* 64 bit frequency */
LARGE_INTEGER liPerfTemp; /* used for query */
UI64 uFreq = FREQ; /* process frequency */
UI64 uOrig; /* original tick */
UI64 uWait; /* tick rate / freq */
UI64 uRem = 0; /* tick rate % freq */
UI64 uPrev; /* previous tick based on original tick */
UI64 uDelta; /* current tick - previous */
/* ... */ /* wait for some event to start thread */
QueryPerformanceFrequency(&liPerfFreq);
QueryPerformanceCounter((PLARGE_INTEGER)&liPerfTemp);
uOrig = uPrev = liPerfTemp.QuadPart;
while(1){
/* update uWait and uRem based on uRem */
uWait = ((UI64)(liPerfFreq.QuadPart) + uRem) / uFreq;
uRem = ((UI64)(liPerfFreq.QuadPart) + uRem) % uFreq;
/* wait for uWait ticks */
while(1){
QueryPerformanceCounter((PLARGE_INTEGER)&liPerfTemp);
uDelta = (UI64)(liPerfTemp.QuadPart - uPrev);
if(uDelta >= uWait)
break;
}
uPrev += uWait;
/* fixed frequency code goes here */
/* along with some type of break when done */
}