internal void CalibrateTimerWithHpet(Hpet hpet, ulong tsc_delay)
{
/* set up the hpet */
ulong init_hpet = 0x0;
hpet.SetMainCounter(init_hpet);
init_hpet = hpet.ReadMainCounter();
/* set up the lapic timer as masked, one shot, divisor of 1 */
uint lapic_val = 0xffffffff;
//uint lapic_div = 11; /* bits 0, 1 and 3 set the divisor */
uint lapic_reg = 0x00010000; /* masked, one-shot, vector 0 */
WriteConfDword(LVT_timer_offset, lapic_reg);
//WriteConfDword(Divide_Conf_offset, lapic_div);
WriteConfDword(Initial_Count_offset, lapic_val);
/* start the hpet */
hpet.EnableMainCounter();
/* perform a delay using the tsc */
ulong init_tsc = libsupcs.x86_64.Cpu.Tsc;
ulong cur_tsc = init_tsc;
while (cur_tsc < (init_tsc + tsc_delay))
{
cur_tsc = libsupcs.x86_64.Cpu.Tsc;
}
/* get the final values of the timers */
ulong lapic_final_val = ReadConfDword(Current_Count_offset);
hpet.DisableMainCounter();
ulong hpet_final_val = hpet.ReadMainCounter();
ulong delta_hpet = hpet_final_val - init_hpet;
ulong delta_lapic = lapic_val - lapic_final_val;
/* At this point:
*
* actual time delay = delta_hpet / hpet_frequency _or_ delta_hpet * hpet_cycle_length
* bus_cycles = delta_lapic * lapic_divisor
*
* bus_frequency = bus_cycles / actual time delay
*/
double actual_time_delay = Convert.ToDouble((long)delta_hpet) * hpet.MainCounterCycleLength;
ulong bus_cycles = delta_lapic * LApicTimerDivisor;
double bus_frequency = Convert.ToDouble((long)bus_cycles) / actual_time_delay;
double bus_frequency_mhz = bus_frequency * 0.000001;
Program.arch.DebugOutput.Write("Bus frequency " + bus_frequency_mhz.ToString() + " Mhz\n");
Formatter.Write(" delta_tsc: ", Program.arch.DebugOutput);
Formatter.Write(cur_tsc - init_tsc, "X", Program.arch.DebugOutput);
Formatter.Write(" init_hpet: ", Program.arch.DebugOutput);
Formatter.Write(init_hpet, "X", Program.arch.DebugOutput);
Formatter.Write(" final_hpet: ", Program.arch.DebugOutput);
Formatter.Write(hpet_final_val, "X", Program.arch.DebugOutput);
Formatter.Write(" delta_hpet: ", Program.arch.DebugOutput);
Formatter.Write(delta_hpet, "d", Program.arch.DebugOutput);
Formatter.Write(" delta_lapic: ", Program.arch.DebugOutput);
Formatter.Write(delta_lapic, "d", Program.arch.DebugOutput);
Formatter.WriteLine(Program.arch.DebugOutput);
lapic_base_freq = bus_frequency;
calibrated = true;
}
internal void CalibrateTimerWithHpet(Hpet hpet)
{
CalibrateTimerWithHpet(hpet, 0x1000000);
}
