sysGetCurrentTime seems wrong

[Fewnity]

I was trying to measure time to check my code execution time, I saw these functions:
sysGetCurrentTime, sysGetSystemTime, __gettime and std::chrono::high_resolution_clock::now(), I tried them all and I don't understand sysGetCurrentTime. (Other function works great)

Here is a test code:

uint64_t sec = 0;
uint64_t nsecStart = 0;
uint64_t nsecEnd = 0;
sysGetCurrentTime(&sec , &nsecStart);
sysSleep(1); // Wait 1 sec
sysGetCurrentTime(&sec , &nsecEnd);

nsec values seems wrong, nsecStart = 942584962 and nsecEnd = 972889799
972889799 - 942584962 = 30304837

Is this function broken? I tried to see the implementation in the cell sdk and to recode it and I still have weird values.
I tried to use the value from sysGetTimebaseFrequency and make something with it but I can't. Any idea?