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           // Note: this lock can be eliminated for single processor systems.
 40           #define PEGASUS_ATOMIC_LOCK "lock ; "
 41           
 42 mike  1.1 #include <Pegasus/Common/Config.h>
 43           
 44           PEGASUS_NAMESPACE_BEGIN
 45           
 46           struct SpinLock
 47           {
 48               // Available when zero.
 49               volatile int lock;
 50           };
 51           
 52           inline void SpinLockCreate(SpinLock& x)
 53           {
 54               // Available when one.
 55               x.lock = 1;
 56           }
 57           
 58           inline void SpinLockDestroy(SpinLock& x)
 59           {
 60           }
 61           
 62           inline void SpinLockLock(SpinLock& x)
 63 mike  1.1 {
 64               // Spin until we are able to obtain a lock.
 65           
 66               for (;;)
 67               {
 68           	// Wait until the lock is available then try to grab it before another
 69           	// thread gets it.
 70           
 71           	if (x.lock == 1)
 72           	{
 73           	    unsigned char isZero;
 74           
 75           	    asm volatile(
 76           		PEGASUS_ATOMIC_LOCK "decl %0; sete %1"
 77           		:"=m" (x.lock), "=qm" (isZero)
 78           		:"m" (x.lock) : "memory");
 79           
 80           	    // If it became zero, then we must have locked it.
 81           
 82           	    if (isZero)
 83           		return;
 84 mike  1.1 
 85           	    // Some other thread locked it. Increment and keep trying.
 86           
 87           	    asm volatile(
 88           		PEGASUS_ATOMIC_LOCK "incl %0"
 89           		:"=m" (x.lock)
 90           		:"m" (x.lock));
 91           	}
 92               }
 93           }
 94           
 95           inline void SpinLockUnlock(SpinLock& x)
 96           {
 97               asm volatile(
 98                   PEGASUS_ATOMIC_LOCK "incl %0"
 99                   :"=m" (x.lock)
100                   :"m" (x.lock));
101           }
102           
103           PEGASUS_NAMESPACE_END
104           
105 mike  1.1 #endif /* Pegasus_SpinLock_LINUX_IX86_GNU_h */