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78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/** @file
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Copyright (C) 2020, vit9696. All rights reserved.
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All rights reserved.
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include "../OcCpuInternals.h"
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#include <Library/BaseLib.h>
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#include <Library/IoLib.h>
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VOID
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EFIAPI
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AsmMeasureTicks (
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IN UINT32 AcpiTicksDuration,
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IN UINT16 TimerAddr,
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OUT UINT32 *AcpiTicksDelta,
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OUT UINT64 *TscTicksDelta
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)
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{
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UINT32 AcpiTick0;
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UINT32 AcpiTick1;
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UINT32 AcpiCurrentDelta;
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UINT64 Tsc0;
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UINT64 Tsc1;
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AcpiTick0 = IoRead32 (TimerAddr);
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Tsc0 = AsmReadTsc ();
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do {
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CpuPause ();
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//
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// Check how many AcpiTicks have passed since we started.
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//
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AcpiTick1 = IoRead32 (TimerAddr);
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if (AcpiTick0 <= AcpiTick1) {
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//
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// No overflow.
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//
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AcpiCurrentDelta = AcpiTick1 - AcpiTick0;
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} else if (AcpiTick0 - AcpiTick1 <= 0x00FFFFFF) {
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//
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// Overflow, 24-bit timer.
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//
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AcpiCurrentDelta = 0x00FFFFFF - AcpiTick0 + AcpiTick1;
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} else {
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//
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// Overflow, 32-bit timer.
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//
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AcpiCurrentDelta = MAX_UINT32 - AcpiTick0 + AcpiTick1;
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}
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//
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// Keep checking AcpiTicks until target is reached.
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//
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} while (AcpiCurrentDelta < AcpiTicksDuration);
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Tsc1 = AsmReadTsc ();
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//
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// On some systems we may end up waiting for notably longer than 100ms,
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// despite disabling all events. Divide by actual time passed as suggested
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// by asava's Clover patch r2668.
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//
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*TscTicksDelta = Tsc1 - Tsc0;
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*AcpiTicksDelta = AcpiCurrentDelta;
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}
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