/** @file
Implementation of synchronization functions.
Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
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.
**/
#include "BaseSynchronizationLibInternals.h"
#define SPIN_LOCK_RELEASED ((UINTN) 1)
#define SPIN_LOCK_ACQUIRED ((UINTN) 2)
/**
Retrieves the architecture specific spin lock alignment requirements for
optimal spin lock performance.
This function retrieves the spin lock alignment requirements for optimal
performance on a given CPU architecture. The spin lock alignment is byte alignment.
It must be a power of two and is returned by this function. If there are no alignment
requirements, then 1 must be returned. The spin lock synchronization
functions must function correctly if the spin lock size and alignment values
returned by this function are not used at all. These values are hints to the
consumers of the spin lock synchronization functions to obtain optimal spin
lock performance.
@return The architecture specific spin lock alignment.
**/
UINTN
EFIAPI
GetSpinLockProperties (
VOID
)
{
return 32;
}
/**
Initializes a spin lock to the released state and returns the spin lock.
This function initializes the spin lock specified by SpinLock to the released
state, and returns SpinLock. Optimal performance can be achieved by calling
GetSpinLockProperties() to determine the size and alignment requirements for
SpinLock.
If SpinLock is NULL, then ASSERT().
@param SpinLock A pointer to the spin lock to initialize to the released
state.
@return SpinLock is in release state.
**/
SPIN_LOCK *
EFIAPI
InitializeSpinLock (
OUT SPIN_LOCK *SpinLock
)
{
ASSERT (SpinLock != NULL);
*SpinLock = SPIN_LOCK_RELEASED;
return SpinLock;
}
/**
Waits until a spin lock can be placed in the acquired state.
This function checks the state of the spin lock specified by SpinLock. If
SpinLock is in the released state, then this function places SpinLock in the
acquired state and returns SpinLock. Otherwise, this function waits
indefinitely for the spin lock to be released, and then places it in the
acquired state and returns SpinLock. All state transitions of SpinLock must
be performed using MP safe mechanisms.
If SpinLock is NULL, then ASSERT().
If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
PcdSpinLockTimeout microseconds, then ASSERT().
@param SpinLock A pointer to the spin lock to place in the acquired state.
@return SpinLock acquired the lock.
**/
SPIN_LOCK *
EFIAPI
AcquireSpinLock (
IN OUT SPIN_LOCK *SpinLock
)
{
UINT64 Current;
UINT64 Previous;
UINT64 Total;
UINT64 Start;
UINT64 End;
UINT64 Timeout;
INT64 Cycle;
INT64 Delta;
if (PcdGet32 (PcdSpinLockTimeout) > 0) {
//
// Get the current timer value
//
Current = GetPerformanceCounter();
//
// Initialize local variables
//
Start = 0;
End = 0;
Total = 0;
//
// Retrieve the performance counter properties and compute the number of performance
// counter ticks required to reach the timeout
//
Timeout = DivU64x32 (
MultU64x32 (
GetPerformanceCounterProperties (&Start, &End),
PcdGet32 (PcdSpinLockTimeout)
),
1000000
);
Cycle = End - Start;
if (Cycle < 0) {
Cycle = -Cycle;
}
Cycle++;
while (!AcquireSpinLockOrFail (SpinLock)) {
CpuPause ();
Previous = Current;
Current = GetPerformanceCounter();
Delta = (INT64) (Current - Previous);
if (Start > End) {
Delta = -Delta;
}
if (Delta < 0) {
Delta += Cycle;
}
Total += Delta;
ASSERT (Total < Timeout);
}
} else {
while (!AcquireSpinLockOrFail (SpinLock)) {
CpuPause ();
}
}
return SpinLock;
}
/**
Attempts to place a spin lock in the acquired state.
This function checks the state of the spin lock specified by SpinLock. If
SpinLock is in the released state, then this function places SpinLock in the
acquired state and returns TRUE. Otherwise, FALSE is returned. All state
transitions of SpinLock must be performed using MP safe mechanisms.
If SpinLock is NULL, then ASSERT().
If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
@param SpinLock A pointer to the spin lock to place in the acquired state.
@retval TRUE SpinLock was placed in the acquired state.
@retval FALSE SpinLock could not be acquired.
**/
BOOLEAN
EFIAPI
AcquireSpinLockOrFail (
IN OUT SPIN_LOCK *SpinLock
)
{
SPIN_LOCK LockValue;
ASSERT (SpinLock != NULL);
LockValue = *SpinLock;
ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
return (BOOLEAN)(
InterlockedCompareExchangePointer (
(VOID**)SpinLock,
(VOID*)SPIN_LOCK_RELEASED,
(VOID*)SPIN_LOCK_ACQUIRED
) == (VOID*)SPIN_LOCK_RELEASED
);
}
/**
Releases a spin lock.
This function places the spin lock specified by SpinLock in the release state
and returns SpinLock.
If SpinLock is NULL, then ASSERT().
If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
@param SpinLock A pointer to the spin lock to release.
@return SpinLock released lock.
**/
SPIN_LOCK *
EFIAPI
ReleaseSpinLock (
IN OUT SPIN_LOCK *SpinLock
)
{
SPIN_LOCK LockValue;
ASSERT (SpinLock != NULL);
LockValue = *SpinLock;
ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
*SpinLock = SPIN_LOCK_RELEASED;
return SpinLock;
}
/**
Performs an atomic increment of an 32-bit unsigned integer.
Performs an atomic increment of the 32-bit unsigned integer specified by
Value and returns the incremented value. The increment operation must be
performed using MP safe mechanisms. The state of the return value is not
guaranteed to be MP safe.
If Value is NULL, then ASSERT().
@param Value A pointer to the 32-bit value to increment.
@return The incremented value.
**/
UINT32
EFIAPI
InterlockedIncrement (
IN UINT32 *Value
)
{
ASSERT (Value != NULL);
return InternalSyncIncrement (Value);
}
/**
Performs an atomic decrement of an 32-bit unsigned integer.
Performs an atomic decrement of the 32-bit unsigned integer specified by
Value and returns the decremented value. The decrement operation must be
performed using MP safe mechanisms. The state of the return value is not
guaranteed to be MP safe.
If Value is NULL, then ASSERT().
@param Value A pointer to the 32-bit value to decrement.
@return The decremented value.
**/
UINT32
EFIAPI
InterlockedDecrement (
IN UINT32 *Value
)
{
ASSERT (Value != NULL);
return InternalSyncDecrement (Value);
}
/**
Performs an atomic compare exchange operation on a 16-bit unsigned integer.
Performs an atomic compare exchange operation on the 16-bit unsigned integer
specified by Value. If Value is equal to CompareValue, then Value is set to
ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue,
then Value is returned. The compare exchange operation must be performed using
MP safe mechanisms.
If Value is NULL, then ASSERT().
@param Value A pointer to the 16-bit value for the compare exchange
operation.
@param CompareValue 16-bit value used in compare operation.
@param ExchangeValue 16-bit value used in exchange operation.
@return The original *Value before exchange.
**/
UINT16
EFIAPI
InterlockedCompareExchange16 (
IN OUT UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.
Performs an atomic compare exchange operation on the 32-bit unsigned integer
specified by Value. If Value is equal to CompareValue, then Value is set to
ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue,
then Value is returned. The compare exchange operation must be performed using
MP safe mechanisms.
If Value is NULL, then ASSERT().
@param Value A pointer to the 32-bit value for the compare exchange
operation.
@param CompareValue 32-bit value used in compare operation.
@param ExchangeValue 32-bit value used in exchange operation.
@return The original *Value before exchange.
**/
UINT32
EFIAPI
InterlockedCompareExchange32 (
IN OUT UINT32 *Value,
IN UINT32 CompareValue,
IN UINT32 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a 64-bit unsigned integer.
Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and
CompareValue is returned. If Value is not equal to CompareValue, then Value is returned.
The compare exchange operation must be performed using MP safe mechanisms.
If Value is NULL, then ASSERT().
@param Value A pointer to the 64-bit value for the compare exchange
operation.
@param CompareValue 64-bit value used in compare operation.
@param ExchangeValue 64-bit value used in exchange operation.
@return The original *Value before exchange.
**/
UINT64
EFIAPI
InterlockedCompareExchange64 (
IN OUT UINT64 *Value,
IN UINT64 CompareValue,
IN UINT64 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a pointer value.
Performs an atomic compare exchange operation on the pointer value specified
by Value. If Value is equal to CompareValue, then Value is set to
ExchangeValue and CompareValue is returned. If Value is not equal to
CompareValue, then Value is returned. The compare exchange operation must be
performed using MP safe mechanisms.
If Value is NULL, then ASSERT().
@param Value A pointer to the pointer value for the compare exchange
operation.
@param CompareValue Pointer value used in compare operation.
@param ExchangeValue Pointer value used in exchange operation.
@return The original *Value before exchange.
**/
VOID *
EFIAPI
InterlockedCompareExchangePointer (
IN OUT VOID **Value,
IN VOID *CompareValue,
IN VOID *ExchangeValue
)
{
UINT8 SizeOfValue;
SizeOfValue = sizeof (*Value);
switch (SizeOfValue) {
case sizeof (UINT32):
return (VOID*)(UINTN)InterlockedCompareExchange32 (
(UINT32*)Value,
(UINT32)(UINTN)CompareValue,
(UINT32)(UINTN)ExchangeValue
);
case sizeof (UINT64):
return (VOID*)(UINTN)InterlockedCompareExchange64 (
(UINT64*)Value,
(UINT64)(UINTN)CompareValue,
(UINT64)(UINTN)ExchangeValue
);
default:
ASSERT (FALSE);
return NULL;
}
}