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Driver HRTHPET

The IA-PC HPET (High Precision Event Timers) is available on most ACPI systems. It typically runs at a rate of several to several hundred MHz. If no ACPI BIOS is found at run time, the Pentium Time Stamp Counter is used instead and this driver behaves exactly as the HRTPENT driver.

Due to the limited range of the HPET timer running in 32 bit mode, applications must read the timer using FTReadTime at least once every few seconds while a time period is being measured. The actual time period depends on the resolution of the timer and can be determined with this code:

RTKFineTime T; 
T.TimeLow  = 0x80000000; 
T.TimeHigh = 0; 
printf("FTReadTime() must be called at least every %i seconds.\n", FTTimeToSeconds(&T));

Typical values are 8 to 500 seconds.

If you prefere to run the driver in 64 bit mode, apply flag DF_HPET_64BIT in RTKConfig.DriverFlags. in this case, periodic reading the timer is not required.

The HPET driver is suitable for single- and multiprocessor applications and is faster than driver HRTPM.

Requirements: Intel Pentium or higher CPU, ACPI BIOS. Incompatible with clock driver CLKHRTPC.

High Resolution Timer

Driver HRTPM

Driver HRTVMF