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/*++
Copyright (c) 2004 - 2007, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
Module Name:
tpl.c
Abstract:
Task priority function
--*/
#include "exec.h"
STATIC
VOID
CoreSetInterruptState (
IN BOOLEAN Enable
)
/*++
Routine Description:
Set Interrupt State
Arguments:
Enable - The state of enable or disable interrupt
Returns:
None
--*/
{
if (gCpu != NULL) {
if (Enable) {
gCpu->EnableInterrupt(gCpu);
} else {
gCpu->DisableInterrupt(gCpu);
}
}
}
//
// Return the highest set bit
//
UINTN
CoreHighestSetBit (
IN UINTN Number
)
/*++
Routine Description:
Return the highest set bit
Arguments:
Number - The value to check
Returns:
Bit position of the highest set bit
--*/
{
UINTN msb;
msb = 31;
while ((msb > 0) && ((Number & ((UINTN)1 << msb)) == 0)) {
msb--;
}
return msb;
}
EFI_BOOTSERVICE
EFI_TPL
EFIAPI
CoreRaiseTpl (
IN EFI_TPL NewTpl
)
/*++
Routine Description:
Raise the task priority level to the new level.
High level is implemented by disabling processor interrupts.
Arguments:
NewTpl - New task priority level
Returns:
The previous task priority level
--*/
{
EFI_TPL OldTpl;
OldTpl = gEfiCurrentTpl;
ASSERT (OldTpl <= NewTpl);
ASSERT (VALID_TPL (NewTpl));
//
// If raising to high level, disable interrupts
//
if (NewTpl >= EFI_TPL_HIGH_LEVEL && OldTpl < EFI_TPL_HIGH_LEVEL) {
CoreSetInterruptState (FALSE);
}
//
// Set the new value
//
gEfiCurrentTpl = NewTpl;
return OldTpl;
}
EFI_BOOTSERVICE
VOID
EFIAPI
CoreRestoreTpl (
IN EFI_TPL NewTpl
)
/*++
Routine Description:
Lowers the task priority to the previous value. If the new
priority unmasks events at a higher priority, they are dispatched.
Arguments:
NewTpl - New, lower, task priority
Returns:
None
--*/
{
EFI_TPL OldTpl;
OldTpl = gEfiCurrentTpl;
ASSERT (NewTpl <= OldTpl);
ASSERT (VALID_TPL (NewTpl));
//
// If lowering below HIGH_LEVEL, make sure
// interrupts are enabled
//
if (OldTpl >= EFI_TPL_HIGH_LEVEL && NewTpl < EFI_TPL_HIGH_LEVEL) {
gEfiCurrentTpl = EFI_TPL_HIGH_LEVEL;
}
//
// Dispatch any pending events
//
while ((-2 << NewTpl) & gEventPending) {
gEfiCurrentTpl = CoreHighestSetBit (gEventPending);
if (gEfiCurrentTpl < EFI_TPL_HIGH_LEVEL) {
CoreSetInterruptState (TRUE);
}
CoreDispatchEventNotifies (gEfiCurrentTpl);
}
//
// Set the new value
//
gEfiCurrentTpl = NewTpl;
//
// If lowering below HIGH_LEVEL, make sure
// interrupts are enabled
//
if (gEfiCurrentTpl < EFI_TPL_HIGH_LEVEL) {
CoreSetInterruptState (TRUE);
}
}
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