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      1 /** @file
      2   Implementation of synchronization functions on EBC.
      3 
      4   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
      5   This program and the accompanying materials
      6   are licensed and made available under the terms and conditions of the BSD License
      7   which accompanies this distribution.  The full text of the license may be found at
      8   http://opensource.org/licenses/bsd-license.php.
      9 
     10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
     11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
     12 
     13 **/
     14 
     15 /**
     16   Performs an atomic compare exchange operation on a 16-bit
     17   unsigned integer.
     18 
     19   Performs an atomic compare exchange operation on the 16-bit
     20   unsigned integer specified by Value.  If Value is equal to
     21   CompareValue, then Value is set to ExchangeValue and
     22   CompareValue is returned.  If Value is not equal to
     23   CompareValue, then Value is returned. The compare exchange
     24   operation must be performed using MP safe mechanisms.
     25 
     26   @param  Value         A pointer to the 16-bit value for the
     27                         compare exchange operation.
     28   @param  CompareValue  16-bit value used in compare operation.
     29   @param  ExchangeValue 16-bit value used in exchange operation.
     30 
     31   @return The original *Value before exchange.
     32 
     33 **/
     34 UINT16
     35 EFIAPI
     36 InternalSyncCompareExchange16 (
     37   IN      volatile UINT16           *Value,
     38   IN      UINT16                    CompareValue,
     39   IN      UINT16                    ExchangeValue
     40   )
     41 {
     42   return *Value != CompareValue ? *Value :
     43            ((*Value = ExchangeValue), CompareValue);
     44 }
     45 
     46 /**
     47   Performs an atomic compare exchange operation on a 32-bit
     48   unsigned integer.
     49 
     50   Performs an atomic compare exchange operation on the 32-bit
     51   unsigned integer specified by Value.  If Value is equal to
     52   CompareValue, then Value is set to ExchangeValue and
     53   CompareValue is returned.  If Value is not equal to
     54   CompareValue, then Value is returned. The compare exchange
     55   operation must be performed using MP safe mechanisms.
     56 
     57   @param  Value         A pointer to the 32-bit value for the
     58                         compare exchange operation.
     59   @param  CompareValue  32-bit value used in compare operation.
     60   @param  ExchangeValue 32-bit value used in exchange operation.
     61 
     62   @return The original *Value before exchange.
     63 
     64 **/
     65 UINT32
     66 EFIAPI
     67 InternalSyncCompareExchange32 (
     68   IN      volatile UINT32           *Value,
     69   IN      UINT32                    CompareValue,
     70   IN      UINT32                    ExchangeValue
     71   )
     72 {
     73   return *Value != CompareValue ? *Value :
     74            ((*Value = ExchangeValue), CompareValue);
     75 }
     76 
     77 /**
     78   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
     79 
     80   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
     81   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
     82   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
     83   The compare exchange operation must be performed using MP safe mechanisms.
     84 
     85   @param  Value         A pointer to the 64-bit value for the compare exchange
     86                         operation.
     87   @param  CompareValue  64-bit value used in compare operation.
     88   @param  ExchangeValue 64-bit value used in exchange operation.
     89 
     90   @return The original *Value before exchange.
     91 
     92 **/
     93 UINT64
     94 EFIAPI
     95 InternalSyncCompareExchange64 (
     96   IN      volatile UINT64           *Value,
     97   IN      UINT64                    CompareValue,
     98   IN      UINT64                    ExchangeValue
     99   )
    100 {
    101   return *Value != CompareValue ? *Value :
    102            ((*Value = ExchangeValue), CompareValue);
    103 }
    104 
    105 /**
    106   Performs an atomic increment of an 32-bit unsigned integer.
    107 
    108   Performs an atomic increment of the 32-bit unsigned integer specified by
    109   Value and returns the incremented value. The increment operation must be
    110   performed using MP safe mechanisms. The state of the return value is not
    111   guaranteed to be MP safe.
    112 
    113   @param  Value A pointer to the 32-bit value to increment.
    114 
    115   @return The incremented value.
    116 
    117 **/
    118 UINT32
    119 EFIAPI
    120 InternalSyncIncrement (
    121   IN      volatile UINT32           *Value
    122   )
    123 {
    124   return ++*Value;
    125 }
    126 
    127 /**
    128   Performs an atomic decrement of an 32-bit unsigned integer.
    129 
    130   Performs an atomic decrement of the 32-bit unsigned integer specified by
    131   Value and returns the decrement value. The decrement operation must be
    132   performed using MP safe mechanisms. The state of the return value is not
    133   guaranteed to be MP safe.
    134 
    135   @param  Value A pointer to the 32-bit value to decrement.
    136 
    137   @return The decrement value.
    138 
    139 **/
    140 UINT32
    141 EFIAPI
    142 InternalSyncDecrement (
    143   IN      volatile UINT32           *Value
    144   )
    145 {
    146   return --*Value;
    147 }
    148