mirror of
https://github.com/ApfelTeeSaft/reactos.git
synced 2026-08-26 19:33:31 +00:00
Dmitry Borisov
82ef7e5d04
Do not rely on a hardcoded ASM instruction offset.
Addendum to commit 45e6d49a29.
CORE-17977
151 lines
4.4 KiB
C
151 lines
4.4 KiB
C
/*
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* PROJECT: NEC PC-98 series HAL
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* LICENSE: GPL-2.0-or-later (https://spdx.org/licenses/GPL-2.0-or-later)
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* PURPOSE: TSC calibration for the busy-wait loop routine
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* COPYRIGHT: Copyright 2011 Timo Kreuzer <[email protected]>
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* Copyright 2026 Dmitry Borisov <[email protected]>
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*/
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/* INCLUDES ******************************************************************/
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#include <hal.h>
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#define NDEBUG
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#include <debug.h>
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#include "delay.h"
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/* GLOBALS *******************************************************************/
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#define SAMPLE_FREQUENCY 1024 // 0.977 ms
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VOID
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__cdecl
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HalpTscCalibrationISR(VOID);
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extern volatile ULONG TscCalibrationPhase;
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extern ULONG64 TscCalibrationArray[NUM_SAMPLES];
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extern UCHAR HalpStallExecutionSerialize;
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/* FUNCTIONS *****************************************************************/
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static
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CODE_SEG("INIT")
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VOID
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HalpPrepareStallExecution(VOID)
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{
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PUCHAR Instruction = &HalpStallExecutionSerialize;
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PKPRCB Prcb = KeGetCurrentPrcb();
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/* xor eax, eax; cpuid */
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ASSERT((Instruction[1] == 0xC0) && // The byte [0] has different encodings
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(Instruction[2] == 0x0F) &&
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(Instruction[3] == 0xA2));
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/*
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* Starting with the Pentium Pro processor it is necessary to force
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* the in-order execution of the RDTSC instruction using a serializing instruction.
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* For more details, please refer to Section 3.1 of
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* Intel "Using the RDTSC Instruction for Performance Monitoring".
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*
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* Patch the KeStallExecutionProcessor function to remove the serializing instruction
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* for the Pentium and Pentium MMX processors because the CPUID instruction is slow.
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*/
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if ((Prcb->CpuType < 6) && !strcmp(Prcb->VendorString, "GenuineIntel"))
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{
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/* Replace "xor eax, eax; cpuid" with "lea esi, [esi+0]" */
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Instruction[0] = 0x8D;
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Instruction[1] = 0x74;
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Instruction[2] = 0x26;
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Instruction[3] = 0x00;
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KeSweepICache(Instruction, 4);
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}
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}
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static
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CODE_SEG("INIT")
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ULONG64
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HalpDoLinearRegression(
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_In_ ULONG XMax,
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_In_reads_(XMax + 1) const ULONG64* ArrayY)
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{
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ULONG X, SumXX;
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ULONG64 SumXY;
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/* Calculate the sum of the squares of X */
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SumXX = (XMax * (XMax + 1) * (2 * XMax + 1)) / 6;
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/* Calculate the sum of the differences to the first value weighted by X */
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for (SumXY = 0, X = 1; X <= XMax; X++)
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{
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SumXY += X * (ArrayY[X] - ArrayY[0]);
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}
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/* Account for sample frequency */
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SumXY *= SAMPLE_FREQUENCY;
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/* Return the quotient of the sums */
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return (SumXY + (SumXX / 2)) / SumXX;
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}
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CODE_SEG("INIT")
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VOID
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NTAPI
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HalpCalibrateStallExecution(VOID)
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{
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ULONG_PTR Flags;
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PVOID PreviousHandler;
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TIMER_CONTROL_PORT_REGISTER TimerControl;
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ULONG TimerFrequency;
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USHORT Period;
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ULONG64 CpuClockFrequency;
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/* Check if the CPU supports RDTSC */
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if (!(KeGetCurrentPrcb()->FeatureBits & KF_RDTSC))
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{
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KeBugCheck(HAL_INITIALIZATION_FAILED);
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}
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Flags = __readeflags();
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_disable();
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PreviousHandler = KeQueryInterruptHandler(PIC_TIMER_IRQ);
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KeRegisterInterruptHandler(PRIMARY_VECTOR_BASE + PIC_TIMER_IRQ, HalpTscCalibrationISR);
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/* Program the PIT for binary mode */
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TimerControl.BcdMode = FALSE;
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TimerControl.OperatingMode = PitOperatingMode2;
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TimerControl.Channel = PitChannel0;
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TimerControl.AccessMode = PitAccessModeLowHigh;
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if (__inbyte(0x42) & 0x20)
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TimerFrequency = TIMER_FREQUENCY_1;
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else
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TimerFrequency = TIMER_FREQUENCY_2;
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Period = (TimerFrequency + (SAMPLE_FREQUENCY / 2)) / SAMPLE_FREQUENCY;
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__outbyte(TIMER_CONTROL_PORT, TimerControl.Bits);
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__outbyte(TIMER_CHANNEL0_DATA_PORT, Period & 0xFF);
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__outbyte(TIMER_CHANNEL0_DATA_PORT, Period >> 8);
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HalEnableSystemInterrupt(PRIMARY_VECTOR_BASE + PIC_TIMER_IRQ, CLOCK2_LEVEL, Latched);
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/* Collect the sample data */
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_enable();
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while (TscCalibrationPhase != (NUM_SAMPLES + 1))
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NOTHING;
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_disable();
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HalDisableSystemInterrupt(PRIMARY_VECTOR_BASE + PIC_TIMER_IRQ, CLOCK2_LEVEL);
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KeRegisterInterruptHandler(PRIMARY_VECTOR_BASE + PIC_TIMER_IRQ, PreviousHandler);
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/* Calculate an average, using simplified linear regression */
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CpuClockFrequency = HalpDoLinearRegression(NUM_SAMPLES - 1, TscCalibrationArray);
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KeGetPcr()->StallScaleFactor = (ULONG)(CpuClockFrequency / 1000000);
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HalpPrepareStallExecution();
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__writeeflags(Flags);
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}
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