[mirror_edk2.git] / MdePkg / Library / BaseLib / SynchronizationMsc.c

/** @file\r
  Implementation of synchronization functions.\r
\r
  Copyright (c) 2006 - 2007, Intel Corporation<BR>\r
  All rights reserved. This program and the accompanying materials\r
  are licensed and made available under the terms and conditions of the BSD License\r
  which accompanies this distribution.  The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
//\r
// Include common header file for this module.\r
//\r
\r
\r
#include "BaseLibInternals.h"\r
\r
//\r
// Microsoft Visual Studio 7.1 Function Prototypes for read write barrier Intrinsics\r
//\r
void    _ReadWriteBarrier (void);\r
#pragma intrinsic(_ReadWriteBarrier)\r
\r
\r
#define SPIN_LOCK_RELEASED          ((UINTN) 1)\r
#define SPIN_LOCK_ACQUIRED          ((UINTN) 2)\r
\r
/**\r
  Retrieves the architecture specific spin lock alignment requirements for\r
  optimal spin lock performance.\r
\r
  This function retrieves the spin lock alignment requirements for optimal\r
  performance on a given CPU architecture. The spin lock alignment must be a\r
  power of two and is returned by this function. If there are no alignment\r
  requirements, then 1 must be returned. The spin lock synchronization\r
  functions must function correctly if the spin lock size and alignment values\r
  returned by this function are not used at all. These values are hints to the\r
  consumers of the spin lock synchronization functions to obtain optimal spin\r
  lock performance.\r
\r
  @return The architecture specific spin lock alignment.\r
\r
**/\r
UINTN\r
EFIAPI\r
GetSpinLockProperties (\r
  VOID\r
  )\r
{\r
  // @bug May use a PCD entry to determine this alignment.\r
  return 32;\r
}\r
\r
/**\r
  Initializes a spin lock to the released state and returns the spin lock.\r
\r
  This function initializes the spin lock specified by SpinLock to the released\r
  state, and returns SpinLock. Optimal performance can be achieved by calling\r
  GetSpinLockProperties() to determine the size and alignment requirements for\r
  SpinLock.\r
\r
  If SpinLock is NULL, then ASSERT().\r
\r
  @param  SpinLock  A pointer to the spin lock to initialize to the released\r
                    state.\r
\r
  @return SpinLock\r
\r
**/\r
SPIN_LOCK *\r
EFIAPI\r
InitializeSpinLock (\r
  OUT     SPIN_LOCK                 *SpinLock\r
  )\r
{\r
  ASSERT (SpinLock != NULL);\r
\r
  _ReadWriteBarrier();\r
  *SpinLock = SPIN_LOCK_RELEASED;\r
  _ReadWriteBarrier();\r
\r
  return SpinLock;\r
}\r
\r
/**\r
  Waits until a spin lock can be placed in the acquired state.\r
\r
  This function checks the state of the spin lock specified by SpinLock. If\r
  SpinLock is in the released state, then this function places SpinLock in the\r
  acquired state and returns SpinLock. Otherwise, this function waits\r
  indefinitely for the spin lock to be released, and then places it in the\r
  acquired state and returns SpinLock. All state transitions of SpinLock must\r
  be performed using MP safe mechanisms.\r
\r
  If SpinLock is NULL, then ASSERT().\r
  If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
  If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in\r
  PcdSpinLockTimeout microseconds, then ASSERT().\r
\r
  @param  SpinLock  A pointer to the spin lock to place in the acquired state.\r
\r
  @return SpinLock\r
\r
**/\r
SPIN_LOCK *\r
EFIAPI\r
AcquireSpinLock (\r
  IN OUT  SPIN_LOCK                 *SpinLock\r
  )\r
{\r
  UINT64  Current;\r
  UINT64  Previous;\r
  UINT64  Total;\r
  UINT64  Start;\r
  UINT64  End;\r
  UINT64  Timeout;\r
  INT64   Cycle;\r
  INT64   Delta;\r
\r
  if (PcdGet32 (PcdSpinLockTimeout) > 0) {\r
    //\r
    // Get the current timer value\r
    //\r
    Current = GetPerformanceCounter();\r
\r
    //\r
    // Initialize local variables\r
    //\r
    Start = 0;\r
    End   = 0;\r
    Total = 0;\r
\r
    //\r
    // Retrieve the performance counter properties and compute the number of performance\r
    // counter ticks required to reach the timeout\r
    //\r
    Timeout = DivU64x32 (\r
                MultU64x32 (\r
                  GetPerformanceCounterProperties (&Start, &End),\r
                  PcdGet32 (PcdSpinLockTimeout)\r
                  ),\r
                1000000\r
                );\r
    Cycle = End - Start;\r
    if (Cycle < 0) {\r
      Cycle = -Cycle;\r
    }\r
    Cycle++;\r
\r
    while (!AcquireSpinLockOrFail (SpinLock)) {\r
      CpuPause ();\r
      Previous = Current;\r
      Current  = GetPerformanceCounter();\r
      Delta = (INT64) (Current - Previous);\r
      if (Start > End) {\r
        Delta = -Delta;\r
      }\r
      if (Delta < 0) {\r
        Delta += Cycle;\r
      }\r
      Total += Delta;\r
      ASSERT (Total < Timeout);\r
    }\r
  } else {\r
    while (!AcquireSpinLockOrFail (SpinLock)) {\r
      CpuPause ();\r
    }\r
  }\r
  return SpinLock;\r
}\r
\r
/**\r
  Attempts to place a spin lock in the acquired state.\r
\r
  This function checks the state of the spin lock specified by SpinLock. If\r
  SpinLock is in the released state, then this function places SpinLock in the\r
  acquired state and returns TRUE. Otherwise, FALSE is returned. All state\r
  transitions of SpinLock must be performed using MP safe mechanisms.\r
\r
  If SpinLock is NULL, then ASSERT().\r
  If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
\r
  @param  SpinLock  A pointer to the spin lock to place in the acquired state.\r
\r
  @retval TRUE  SpinLock was placed in the acquired state.\r
  @retval FALSE SpinLock could not be acquired.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
AcquireSpinLockOrFail (\r
  IN OUT  SPIN_LOCK                 *SpinLock\r
  )\r
{\r
  SPIN_LOCK   LockValue;\r
  VOID        *Result;\r
  \r
  ASSERT (SpinLock != NULL);\r
\r
  LockValue = *SpinLock;\r
  ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);\r
\r
  _ReadWriteBarrier ();\r
  Result = InterlockedCompareExchangePointer (\r
             (VOID**)SpinLock,\r
             (VOID*)SPIN_LOCK_RELEASED,\r
             (VOID*)SPIN_LOCK_ACQUIRED\r
           );\r
\r
  _ReadWriteBarrier ();\r
  return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);\r
}\r
\r
/**\r
  Releases a spin lock.\r
\r
  This function places the spin lock specified by SpinLock in the release state\r
  and returns SpinLock.\r
\r
  If SpinLock is NULL, then ASSERT().\r
  If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
\r
  @param  SpinLock  A pointer to the spin lock to release.\r
\r
  @return SpinLock\r
\r
**/\r
SPIN_LOCK *\r
EFIAPI\r
ReleaseSpinLock (\r
  IN OUT  SPIN_LOCK                 *SpinLock\r
  )\r
{\r
  SPIN_LOCK    LockValue;\r
\r
  ASSERT (SpinLock != NULL);\r
\r
  LockValue = *SpinLock;\r
  ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);\r
\r
  _ReadWriteBarrier ();\r
  *SpinLock = SPIN_LOCK_RELEASED;\r
  _ReadWriteBarrier ();\r
\r
  return SpinLock;\r
}\r
\r
/**\r
  Performs an atomic increment of an 32-bit unsigned integer.\r
\r
  Performs an atomic increment of the 32-bit unsigned integer specified by\r
  Value and returns the incremented value. The increment operation must be\r
  performed using MP safe mechanisms. The state of the return value is not\r
  guaranteed to be MP safe.\r
\r
  If Value is NULL, then ASSERT().\r
\r
  @param  Value A pointer to the 32-bit value to increment.\r
\r
  @return The incremented value.\r
\r
**/\r
UINT32\r
EFIAPI\r
InterlockedIncrement (\r
  IN      UINT32                    *Value\r
  )\r
{\r
  ASSERT (Value != NULL);\r
  return InternalSyncIncrement (Value);\r
}\r
\r
/**\r
  Performs an atomic decrement of an 32-bit unsigned integer.\r
\r
  Performs an atomic decrement of the 32-bit unsigned integer specified by\r
  Value and returns the decremented value. The decrement operation must be\r
  performed using MP safe mechanisms. The state of the return value is not\r
  guaranteed to be MP safe.\r
\r
  If Value is NULL, then ASSERT().\r
\r
  @param  Value A pointer to the 32-bit value to decrement.\r
\r
  @return The decremented value.\r
\r
**/\r
UINT32\r
EFIAPI\r
InterlockedDecrement (\r
  IN      UINT32                    *Value\r
  )\r
{\r
  ASSERT (Value != NULL);\r
  return InternalSyncDecrement (Value);\r
}\r
\r
/**\r
  Performs an atomic compare exchange operation on a 32-bit unsigned integer.\r
\r
  Performs an atomic compare exchange operation on the 32-bit unsigned integer\r
  specified by Value.  If Value is equal to CompareValue, then Value is set to \r
  ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,\r
  then Value is returned.  The compare exchange operation must be performed using \r
  MP safe mechanisms.\r
\r
  If Value is NULL, then ASSERT().\r
\r
  @param  Value         A pointer to the 32-bit value for the compare exchange\r
                        operation.\r
  @param  CompareValue  32-bit value used in compare operation.\r
  @param  ExchangeValue 32-bit value used in exchange operation.\r
\r
  @return The original *Value before exchange.\r
\r
**/\r
UINT32\r
EFIAPI\r
InterlockedCompareExchange32 (\r
  IN OUT  UINT32                    *Value,\r
  IN      UINT32                    CompareValue,\r
  IN      UINT32                    ExchangeValue\r
  )\r
{\r
  ASSERT (Value != NULL);\r
  return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);\r
}\r
\r
/**\r
  Performs an atomic compare exchange operation on a 64-bit unsigned integer.\r
\r
  Performs an atomic compare exchange operation on the 64-bit unsigned integer specified \r
  by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and \r
  CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned. \r
  The compare exchange operation must be performed using MP safe mechanisms.\r
\r
  If Value is NULL, then ASSERT().\r
\r
  @param  Value         A pointer to the 64-bit value for the compare exchange\r
                        operation.\r
  @param  CompareValue  64-bit value used in compare operation.\r
  @param  ExchangeValue 64-bit value used in exchange operation.\r
\r
  @return The original *Value before exchange.\r
\r
**/\r
UINT64\r
EFIAPI\r
InterlockedCompareExchange64 (\r
  IN OUT  UINT64                    *Value,\r
  IN      UINT64                    CompareValue,\r
  IN      UINT64                    ExchangeValue\r
  )\r
{\r
  ASSERT (Value != NULL);\r
  return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);\r
}\r
\r
/**\r
  Performs an atomic compare exchange operation on a pointer value.\r
\r
  Performs an atomic compare exchange operation on the pointer value specified\r
  by Value. If Value is equal to CompareValue, then Value is set to\r
  ExchangeValue and CompareValue is returned. If Value is not equal to\r
  CompareValue, then Value is returned. The compare exchange operation must be\r
  performed using MP safe mechanisms.\r
\r
  If Value is NULL, then ASSERT().\r
\r
  @param  Value         A pointer to the pointer value for the compare exchange\r
                        operation.\r
  @param  CompareValue  Pointer value used in compare operation.\r
  @param  ExchangeValue Pointer value used in exchange operation.\r
\r
**/\r
VOID *\r
EFIAPI\r
InterlockedCompareExchangePointer (\r
  IN OUT  VOID                      **Value,\r
  IN      VOID                      *CompareValue,\r
  IN      VOID                      *ExchangeValue\r
  )\r
{\r
  UINT8  SizeOfValue;\r
\r
  SizeOfValue = sizeof (*Value);\r
\r
  switch (SizeOfValue) {\r
    case sizeof (UINT32):\r
      return (VOID*)(UINTN)InterlockedCompareExchange32 (\r
                             (UINT32*)Value,\r
                             (UINT32)(UINTN)CompareValue,\r
                             (UINT32)(UINTN)ExchangeValue\r
                             );\r
    case sizeof (UINT64):\r
      return (VOID*)(UINTN)InterlockedCompareExchange64 (\r
                             (UINT64*)Value,\r
                             (UINT64)(UINTN)CompareValue,\r
                             (UINT64)(UINTN)ExchangeValue\r
                             );\r
    default:\r
      ASSERT (FALSE);\r
      return NULL;\r
  }\r
}\r
Commit	Line	Data
e1f414b6	1	/** @file\r
	2	Implementation of synchronization functions.\r
	3	\r
	4	Copyright (c) 2006 - 2007, Intel Corporation<BR>\r
	5	All rights reserved. This program and the accompanying materials\r
	6	are licensed and made available under the terms and conditions of the BSD License\r
	7	which accompanies this distribution. The full text of the license may be found at\r
	8	http://opensource.org/licenses/bsd-license.php\r
	9	\r
	10	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	11	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	12	\r
e1f414b6	13	**/\r
	14	\r
	15	//\r
	16	// Include common header file for this module.\r
	17	//\r
f734a10a	18	\r
e1f414b6	19	\r
	20	#include "BaseLibInternals.h"\r
	21	\r
	22	//\r
	23	// Microsoft Visual Studio 7.1 Function Prototypes for read write barrier Intrinsics\r
	24	//\r
	25	void _ReadWriteBarrier (void);\r
	26	#pragma intrinsic(_ReadWriteBarrier)\r
	27	\r
	28	\r
	29	#define SPIN_LOCK_RELEASED ((UINTN) 1)\r
	30	#define SPIN_LOCK_ACQUIRED ((UINTN) 2)\r
	31	\r
	32	/**\r
	33	Retrieves the architecture specific spin lock alignment requirements for\r
	34	optimal spin lock performance.\r
	35	\r
	36	This function retrieves the spin lock alignment requirements for optimal\r
	37	performance on a given CPU architecture. The spin lock alignment must be a\r
	38	power of two and is returned by this function. If there are no alignment\r
	39	requirements, then 1 must be returned. The spin lock synchronization\r
	40	functions must function correctly if the spin lock size and alignment values\r
	41	returned by this function are not used at all. These values are hints to the\r
	42	consumers of the spin lock synchronization functions to obtain optimal spin\r
	43	lock performance.\r
	44	\r
	45	@return The architecture specific spin lock alignment.\r
	46	\r
	47	**/\r
	48	UINTN\r
	49	EFIAPI\r
	50	GetSpinLockProperties (\r
	51	VOID\r
	52	)\r
	53	{\r
	54	// @bug May use a PCD entry to determine this alignment.\r
	55	return 32;\r
	56	}\r
	57	\r
	58	/**\r
	59	Initializes a spin lock to the released state and returns the spin lock.\r
	60	\r
	61	This function initializes the spin lock specified by SpinLock to the released\r
	62	state, and returns SpinLock. Optimal performance can be achieved by calling\r
	63	GetSpinLockProperties() to determine the size and alignment requirements for\r
	64	SpinLock.\r
	65	\r
	66	If SpinLock is NULL, then ASSERT().\r
	67	\r
	68	@param SpinLock A pointer to the spin lock to initialize to the released\r
	69	state.\r
	70	\r
	71	@return SpinLock\r
	72	\r
	73	**/\r
	74	SPIN_LOCK *\r
	75	EFIAPI\r
	76	InitializeSpinLock (\r
	77	OUT SPIN_LOCK *SpinLock\r
	78	)\r
	79	{\r
	80	ASSERT (SpinLock != NULL);\r
	81	\r
	82	_ReadWriteBarrier();\r
83	*SpinLock = SPIN_LOCK_RELEASED;\r
84	_ReadWriteBarrier();\r
85	\r
86	return SpinLock;\r
87	}\r
88	\r
89	/**\r
90	Waits until a spin lock can be placed in the acquired state.\r
91	\r
92	This function checks the state of the spin lock specified by SpinLock. If\r
93	SpinLock is in the released state, then this function places SpinLock in the\r
94	acquired state and returns SpinLock. Otherwise, this function waits\r
95	indefinitely for the spin lock to be released, and then places it in the\r
96	acquired state and returns SpinLock. All state transitions of SpinLock must\r
97	be performed using MP safe mechanisms.\r
98	\r
99	If SpinLock is NULL, then ASSERT().\r
100	If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
101	If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in\r
102	PcdSpinLockTimeout microseconds, then ASSERT().\r
103	\r
104	@param SpinLock A pointer to the spin lock to place in the acquired state.\r
105	\r
106	@return SpinLock\r
107	\r
108	**/\r
109	SPIN_LOCK *\r
110	EFIAPI\r
111	AcquireSpinLock (\r
112	IN OUT SPIN_LOCK *SpinLock\r
113	)\r
114	{\r
a82da388	115	UINT64 Current;\r
	116	UINT64 Previous;\r
	117	UINT64 Total;\r
	118	UINT64 Start;\r
	119	UINT64 End;\r
	120	UINT64 Timeout;\r
	121	INT64 Cycle;\r
	122	INT64 Delta;\r
e1f414b6	123	\r
e1f414b6	124	if (PcdGet32 (PcdSpinLockTimeout) > 0) {\r
a82da388	125	//\r
	126	// Get the current timer value\r
	127	//\r
	128	Current = GetPerformanceCounter();\r
	129	\r
	130	//\r
	131	// Initialize local variables\r
	132	//\r
	133	Start = 0;\r
	134	End = 0;\r
	135	Total = 0;\r
	136	\r
	137	//\r
	138	// Retrieve the performance counter properties and compute the number of performance\r
	139	// counter ticks required to reach the timeout\r
	140	//\r
e1f414b6	141	Timeout = DivU64x32 (\r
	142	MultU64x32 (\r
	143	GetPerformanceCounterProperties (&Start, &End),\r
	144	PcdGet32 (PcdSpinLockTimeout)\r
	145	),\r
	146	1000000\r
	147	);\r
a82da388	148	Cycle = End - Start;\r
	149	if (Cycle < 0) {\r
	150	Cycle = -Cycle;\r
	151	}\r
	152	Cycle++;\r
	153	\r
	154	while (!AcquireSpinLockOrFail (SpinLock)) {\r
	155	CpuPause ();\r
	156	Previous = Current;\r
	157	Current = GetPerformanceCounter();\r
	158	Delta = (INT64) (Current - Previous);\r
	159	if (Start > End) {\r
	160	Delta = -Delta;\r
	161	}\r
	162	if (Delta < 0) {\r
	163	Delta += Cycle;\r
	164	}\r
	165	Total += Delta;\r
	166	ASSERT (Total < Timeout);\r
	167	}\r
	168	} else {\r
	169	while (!AcquireSpinLockOrFail (SpinLock)) {\r
	170	CpuPause ();\r
e1f414b6	171	}\r
e1f414b6	172	}\r
	173	return SpinLock;\r
	174	}\r
	175	\r
	176	/**\r
	177	Attempts to place a spin lock in the acquired state.\r
	178	\r
	179	This function checks the state of the spin lock specified by SpinLock. If\r
	180	SpinLock is in the released state, then this function places SpinLock in the\r
	181	acquired state and returns TRUE. Otherwise, FALSE is returned. All state\r
	182	transitions of SpinLock must be performed using MP safe mechanisms.\r
	183	\r
	184	If SpinLock is NULL, then ASSERT().\r
	185	If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
	186	\r
	187	@param SpinLock A pointer to the spin lock to place in the acquired state.\r
	188	\r
	189	@retval TRUE SpinLock was placed in the acquired state.\r
	190	@retval FALSE SpinLock could not be acquired.\r
	191	\r
	192	**/\r
	193	BOOLEAN\r
	194	EFIAPI\r
	195	AcquireSpinLockOrFail (\r
	196	IN OUT SPIN_LOCK *SpinLock\r
	197	)\r
	198	{\r
	199	SPIN_LOCK LockValue;\r
	200	VOID *Result;\r
	201	\r
	202	ASSERT (SpinLock != NULL);\r
	203	\r
	204	LockValue = *SpinLock;\r
	205	ASSERT (LockValue == SPIN_LOCK_ACQUIRED \|\| LockValue == SPIN_LOCK_RELEASED);\r
	206	\r
	207	_ReadWriteBarrier ();\r
	208	Result = InterlockedCompareExchangePointer (\r
	209	(VOID**)SpinLock,\r
	210	(VOID*)SPIN_LOCK_RELEASED,\r
	211	(VOID*)SPIN_LOCK_ACQUIRED\r
	212	);\r
	213	\r
	214	_ReadWriteBarrier ();\r
	215	return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);\r
	216	}\r
	217	\r
	218	/**\r
	219	Releases a spin lock.\r
	220	\r
	221	This function places the spin lock specified by SpinLock in the release state\r
	222	and returns SpinLock.\r
	223	\r
	224	If SpinLock is NULL, then ASSERT().\r
	225	If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().\r
	226	\r
	227	@param SpinLock A pointer to the spin lock to release.\r
	228	\r
	229	@return SpinLock\r
	230	\r
	231	**/\r
	232	SPIN_LOCK *\r
	233	EFIAPI\r
	234	ReleaseSpinLock (\r
	235	IN OUT SPIN_LOCK *SpinLock\r
236	)\r
237	{\r
238	SPIN_LOCK LockValue;\r
239	\r
240	ASSERT (SpinLock != NULL);\r
241	\r
242	LockValue = *SpinLock;\r
243	ASSERT (LockValue == SPIN_LOCK_ACQUIRED \|\| LockValue == SPIN_LOCK_RELEASED);\r
244	\r
245	_ReadWriteBarrier ();\r
246	*SpinLock = SPIN_LOCK_RELEASED;\r
247	_ReadWriteBarrier ();\r
248	\r
249	return SpinLock;\r
250	}\r
251	\r
252	/**\r
253	Performs an atomic increment of an 32-bit unsigned integer.\r
254	\r
255	Performs an atomic increment of the 32-bit unsigned integer specified by\r
256	Value and returns the incremented value. The increment operation must be\r
257	performed using MP safe mechanisms. The state of the return value is not\r
258	guaranteed to be MP safe.\r
259	\r
260	If Value is NULL, then ASSERT().\r
261	\r
262	@param Value A pointer to the 32-bit value to increment.\r
263	\r
264	@return The incremented value.\r
265	\r
266	**/\r
267	UINT32\r
268	EFIAPI\r
269	InterlockedIncrement (\r
270	IN UINT32 *Value\r
271	)\r
272	{\r
273	ASSERT (Value != NULL);\r
274	return InternalSyncIncrement (Value);\r
275	}\r
276	\r
277	/**\r
278	Performs an atomic decrement of an 32-bit unsigned integer.\r
279	\r
280	Performs an atomic decrement of the 32-bit unsigned integer specified by\r
281	Value and returns the decremented value. The decrement operation must be\r
282	performed using MP safe mechanisms. The state of the return value is not\r
283	guaranteed to be MP safe.\r
284	\r
285	If Value is NULL, then ASSERT().\r
286	\r
287	@param Value A pointer to the 32-bit value to decrement.\r
288	\r
289	@return The decremented value.\r
290	\r
291	**/\r
292	UINT32\r
293	EFIAPI\r
294	InterlockedDecrement (\r
295	IN UINT32 *Value\r
296	)\r
297	{\r
298	ASSERT (Value != NULL);\r
299	return InternalSyncDecrement (Value);\r
300	}\r
301	\r
302	/**\r
303	Performs an atomic compare exchange operation on a 32-bit unsigned integer.\r
304	\r
305	Performs an atomic compare exchange operation on the 32-bit unsigned integer\r
306	specified by Value. If Value is equal to CompareValue, then Value is set to \r
307	ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue,\r
308	then Value is returned. The compare exchange operation must be performed using \r
309	MP safe mechanisms.\r
310	\r
311	If Value is NULL, then ASSERT().\r
312	\r
313	@param Value A pointer to the 32-bit value for the compare exchange\r
314	operation.\r
315	@param CompareValue 32-bit value used in compare operation.\r
316	@param ExchangeValue 32-bit value used in exchange operation.\r
317	\r
318	@return The original *Value before exchange.\r
319	\r
320	**/\r
321	UINT32\r
322	EFIAPI\r
323	InterlockedCompareExchange32 (\r
324	IN OUT UINT32 *Value,\r
325	IN UINT32 CompareValue,\r
326	IN UINT32 ExchangeValue\r
327	)\r
328	{\r
329	ASSERT (Value != NULL);\r
330	return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);\r
331	}\r
332	\r
333	/**\r
334	Performs an atomic compare exchange operation on a 64-bit unsigned integer.\r
335	\r
336	Performs an atomic compare exchange operation on the 64-bit unsigned integer specified \r
337	by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and \r
338	CompareValue is returned. If Value is not equal to CompareValue, then Value is returned. \r
339	The compare exchange operation must be performed using MP safe mechanisms.\r
340	\r
341	If Value is NULL, then ASSERT().\r
342	\r
343	@param Value A pointer to the 64-bit value for the compare exchange\r
344	operation.\r
345	@param CompareValue 64-bit value used in compare operation.\r
346	@param ExchangeValue 64-bit value used in exchange operation.\r
347	\r
348	@return The original *Value before exchange.\r
349	\r
350	**/\r
351	UINT64\r
352	EFIAPI\r
353	InterlockedCompareExchange64 (\r
354	IN OUT UINT64 *Value,\r
355	IN UINT64 CompareValue,\r
356	IN UINT64 ExchangeValue\r
357	)\r
358	{\r
359	ASSERT (Value != NULL);\r
360	return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);\r
361	}\r
362	\r
363	/**\r
364	Performs an atomic compare exchange operation on a pointer value.\r
365	\r
366	Performs an atomic compare exchange operation on the pointer value specified\r
367	by Value. If Value is equal to CompareValue, then Value is set to\r
368	ExchangeValue and CompareValue is returned. If Value is not equal to\r
369	CompareValue, then Value is returned. The compare exchange operation must be\r
370	performed using MP safe mechanisms.\r
371	\r
372	If Value is NULL, then ASSERT().\r
373	\r
374	@param Value A pointer to the pointer value for the compare exchange\r
375	operation.\r
376	@param CompareValue Pointer value used in compare operation.\r
377	@param ExchangeValue Pointer value used in exchange operation.\r
378	\r
379	**/\r
380	VOID *\r
381	EFIAPI\r
382	InterlockedCompareExchangePointer (\r
383	IN OUT VOID **Value,\r
384	IN VOID *CompareValue,\r
385	IN VOID *ExchangeValue\r
386	)\r
387	{\r
388	UINT8 SizeOfValue;\r
389	\r
390	SizeOfValue = sizeof (*Value);\r
391	\r
392	switch (SizeOfValue) {\r
393	case sizeof (UINT32):\r
394	return (VOID*)(UINTN)InterlockedCompareExchange32 (\r
395	(UINT32*)Value,\r
396	(UINT32)(UINTN)CompareValue,\r
397	(UINT32)(UINTN)ExchangeValue\r
398	);\r
399	case sizeof (UINT64):\r
400	return (VOID*)(UINTN)InterlockedCompareExchange64 (\r
401	(UINT64*)Value,\r
402	(UINT64)(UINTN)CompareValue,\r
403	(UINT64)(UINTN)ExchangeValue\r
404	);\r
405	default:\r
406	ASSERT (FALSE);\r
407	return NULL;\r
408	}\r
409	}\r