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Macros
#define	NUM_SAMPLES 4

#define	MSR_RDTSC 0x10

#define	KiGetIdtEntry(Pcr, Vector) &((Pcr)->IDT[Vector])

Functions
void __cdecl	TscCalibrationISR (void)

VOID NTAPI	HalpInitializeTsc (void)

Variables
LARGE_INTEGER	HalpCpuClockFrequency

Macro Definition Documentation

◆ KiGetIdtEntry

#define KiGetIdtEntry	(	Pcr,
		Vector
	)	&((Pcr)->IDT[Vector])

Definition at line 17 of file tsc.h.

◆ MSR_RDTSC

#define MSR_RDTSC 0x10

Definition at line 6 of file tsc.h.

◆ NUM_SAMPLES

#define NUM_SAMPLES 4

Definition at line 5 of file tsc.h.

Function Documentation

◆ HalpInitializeTsc()

VOID NTAPI HalpInitializeTsc ( void )

Definition at line 55 of file tsc.c.

 {
     ULONG_PTR Flags;
     PVOID PreviousHandler;
     UCHAR RegisterA, RegisterB;
 
     /* Check if the CPU supports RDTSC */
     if (!(KeGetCurrentPrcb()->FeatureBits & KF_RDTSC))
     {
         KeBugCheck(HAL_INITIALIZATION_FAILED);
     }
 
      /* Save flags and disable interrupts */
     Flags = __readeflags();
     _disable();
 
     /* Enable the periodic interrupt in the CMOS */
     RegisterB = HalpReadCmos(RTC_REGISTER_B);
     HalpWriteCmos(RTC_REGISTER_B, RegisterB | RTC_REG_B_PI);
 
     /* Modify register A to RTC_MODE to get SAMPLE_FREQUENCY */
     RegisterA = HalpReadCmos(RTC_REGISTER_A);
     RegisterA = (RegisterA & 0xF0) | RTC_MODE;
     HalpWriteCmos(RTC_REGISTER_A, RegisterA);
 
     /* Save old IDT entry */
     PreviousHandler = KeQueryInterruptHandler(APIC_CLOCK_VECTOR);
 
     /* Set the calibration ISR */
     KeRegisterInterruptHandler(APIC_CLOCK_VECTOR, TscCalibrationISR);
 
     /* Reset TSC value to 0 */
     __writemsr(MSR_RDTSC, 0);
 
     /* Enable the timer interrupt */
     HalEnableSystemInterrupt(APIC_CLOCK_VECTOR, CLOCK_LEVEL, Latched);
 
     /* Read register C, so that the next interrupt can happen */
     HalpReadCmos(RTC_REGISTER_C);
 
     /* Wait for completion */
     _enable();
     while (TscCalibrationPhase < NUM_SAMPLES) _ReadWriteBarrier();
     _disable();
 
     /* Disable the periodic interrupt in the CMOS */
     HalpWriteCmos(RTC_REGISTER_B, RegisterB & ~RTC_REG_B_PI);
 
     /* Disable the timer interrupt */
     HalDisableSystemInterrupt(APIC_CLOCK_VECTOR, CLOCK_LEVEL);
 
     /* Restore the previous handler */
     KeRegisterInterruptHandler(APIC_CLOCK_VECTOR, PreviousHandler);
 
     /* Calculate an average, using simplified linear regression */
     HalpCpuClockFrequency.QuadPart = DoLinearRegression(NUM_SAMPLES - 1,
                                                         TscCalibrationArray);
 
     /* Restore flags */
     __writeeflags(Flags);
 
 }

Referenced by HalpCalibrateStallExecution().

◆ TscCalibrationISR()

void __cdecl TscCalibrationISR ( void )

Referenced by HalpInitializeTsc().

Variable Documentation

◆ HalpCpuClockFrequency

LARGE_INTEGER HalpCpuClockFrequency

Definition at line 17 of file tsc.c.

Referenced by HalpCalibrateStallExecution(), HalpInitializeTsc(), and KeQueryPerformanceCounter().

Macros

Functions

Variables