1 karl  1.3 //%2006////////////////////////////////////////////////////////////////////////

  2 mike  1.1 //
  3           // Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
  4           // Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
  5           // Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
  6           // IBM Corp.; EMC Corporation, The Open Group.
  7           // Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
  8           // IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
  9           // Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 10           // EMC Corporation; VERITAS Software Corporation; The Open Group.

 11 karl  1.3 // Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 12           // EMC Corporation; Symantec Corporation; The Open Group.

 13 mike  1.1 //
 14           // Permission is hereby granted, free of charge, to any person obtaining a copy
 15           // of this software and associated documentation files (the "Software"), to
 16           // deal in the Software without restriction, including without limitation the
 17           // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 18           // sell copies of the Software, and to permit persons to whom the Software is
 19           // furnished to do so, subject to the following conditions:

 20 karl  1.3 // 

 21 mike  1.1 // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
 22           // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
 23           // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
 24           // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 25           // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 26           // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 27           // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 28           // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 29           //
 30           //==============================================================================
 31           //
 32           // Author: Mike Brasher, Inova Europe (mike-brasher@austin.rr.com)
 33           //
 34           //%/////////////////////////////////////////////////////////////////////////////
 35           
 36           #ifndef Pegasus_SpinLock_LINUX_IX86_GNU_h
 37           #define Pegasus_SpinLock_LINUX_IX86_GNU_h
 38           
 39           #include <Pegasus/Common/Config.h>
 40           #include <machine/sys/inline.h>
 41           
 42 mike  1.1 PEGASUS_NAMESPACE_BEGIN
 43           
 44           struct SpinLock
 45           {
 46               // Available when zero.
 47               volatile Uint32 lock;
 48           };
 49           
 50           inline void SpinLockCreate(SpinLock& x)
 51           {
 52               x.lock = 0;
 53           }
 54           
 55           inline void SpinLockDestroy(SpinLock& x)
 56           {
 57           }
 58           
 59           inline void SpinLockLock(SpinLock& x)
 60           {
 61               // Spin until we are able to obtain a lock.
 62           
 63 mike  1.1     for (;;)
 64               {
 65           	// Wait until the lock is zero (unlocked) and then try to grab it
 66           	// before some other thread gets it.
 67           
 68           	if (x.lock == 0)
 69           	{
 70           	    // Try to grab the lock (by performing an increment and test
 71           	    // operation).
 72           
 73           	    uint32 tmp = _Asm_fetchadd(
 74           		(_Asm_fasz)_FASZ_W,
 75           		(_Asm_sem)_SEM_ACQ,
 76           		(volatile uint32*)&x.lock,
 77           		(int)-1,
 78           		(_Asm_ldhint)LDHINT_NONE);
 79           
 80           	    // If we got the lock then the old value was zero (available).
 81           	    // The lock is now one or greater (other threads may have 
 82           	    // incremented as well).
 83           
 84 mike  1.1 	    if (tmp == 0)
 85           		return;
 86           
 87           	    // Some other thread must have gotten it before we did (tmp will
 88           	    // be greater than one since some other thread incremented it too).
 89           	    // So decrement the lock and keep trying.
 90           
 91           	    _Asm_fetchadd(
 92           		(_Asm_fasz)_FASZ_W,
 93           		(_Asm_sem)_SEM_ACQ,
 94           		(volatile uint32*)&x.lock,
 95           		(int)-1,
 96           		(_Asm_ldhint)LDHINT_NONE);
 97           	}
 98               }
 99           }
100           
101           inline void SpinLockUnlock(SpinLock& x)
102           {
103               _Asm_fetchadd(
104           	(_Asm_fasz)_FASZ_W,
105 mike  1.1 	(_Asm_sem)_SEM_ACQ,
106           	(volatile uint32*)&x.lock,
107           	(int)-1,
108           	(_Asm_ldhint)LDHINT_NONE);
109           }
110           
111           PEGASUS_NAMESPACE_END
112           
113           #endif /* Pegasus_SpinLock_LINUX_IX86_GNU_h */