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88 lines
2.4 KiB
C
88 lines
2.4 KiB
C
/** @file
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UEFI Miscellaneous boot Services Stall service implementation
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Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
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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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//
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// Include statements
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//
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#include "DxeMain.h"
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/**
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Internal worker function to call the Metronome Architectural Protocol for
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the number of ticks specified by the UINT64 Counter value. WaitForTick()
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service of the Metronome Architectural Protocol uses a UINT32 for the number
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of ticks to wait, so this function loops when Counter is larger than 0xffffffff.
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@param Counter Number of ticks to wait.
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**/
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VOID
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CoreInternalWaitForTick (
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IN UINT64 Counter
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)
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{
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while ((Counter & 0xffffffff00000000ULL) != 0) {
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gMetronome->WaitForTick (gMetronome, 0xffffffff);
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Counter -= 0xffffffff;
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}
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gMetronome->WaitForTick (gMetronome, (UINT32)Counter);
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}
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/**
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Introduces a fine-grained stall.
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@param Microseconds The number of microseconds to stall execution.
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@retval EFI_SUCCESS Execution was stalled for at least the requested
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amount of microseconds.
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@retval EFI_NOT_AVAILABLE_YET gMetronome is not available yet
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**/
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EFI_STATUS
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EFIAPI
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CoreStall (
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IN UINTN Microseconds
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)
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{
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UINT32 Counter;
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UINT32 Remainder;
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if (gMetronome == NULL) {
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return EFI_NOT_AVAILABLE_YET;
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}
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//
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// Calculate the number of ticks by dividing the number of microseconds by
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// the TickPeriod.
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// Calculation is based on 100ns unit.
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//
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Counter = (UINT32) DivU64x32Remainder (
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Microseconds * 10,
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gMetronome->TickPeriod,
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&Remainder
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);
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//
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// Call WaitForTick for Counter + 1 ticks to try to guarantee Counter tick
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// periods, thus attempting to ensure Microseconds of stall time.
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//
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if (Remainder != 0) {
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Counter++;
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}
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gMetronome->WaitForTick (gMetronome, Counter);
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return EFI_SUCCESS;
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}
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