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Public API Reference

csutil/threading/atomicops_gcc_arm.h
00001 /*
00002   Copyright (C) 2010 by Stefano Angeleri
00003                 2006 by Marten Svanfeldt
00004 
00005   This library is free software; you can redistribute it and/or
00006   modify it under the terms of the GNU Lesser General Public
00007   License as published by the Free Software Foundation; either
00008   version 2 of the License, or (at your option) any later version.
00009 
00010   This library is distributed in the hope that it will be useful,
00011   but WITHOUT ANY WARRANTY; without even the implied warranty of
00012   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013   Library General Public License for more details.
00014 
00015   You should have received a copy of the GNU Library General Public
00016   License along with this library; if not, write to the Free
00017   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00018 */
00019 
00020 #ifndef __CS_CSUTIL_ATOMICOPS_GCC_ARM_H__
00021 #define __CS_CSUTIL_ATOMICOPS_GCC_ARM_H__
00022 
00023 #ifndef DOXYGEN_RUN
00024 
00025 namespace CS
00026 {
00027 namespace Threading
00028 {
00029   class CS_CRYSTALSPACE_EXPORT AtomicOperationsArmGCC
00030   {
00031 
00032     private:
00033 
00034     //NOTE: This could be a big problem with static linking but 
00035     //      I couldn't find a better way to implement it.
00036     //      (Each plugin will have his copy making the lock useless)
00037     static char AtomicLock;
00038 
00039     inline static char Swpb(volatile char *target, char value)
00040     {
00041        register char ret;
00042        asm volatile("swpb %0 , %2, [%3]"
00043                     : "=&r"(ret), "=m" (*target)
00044                     : "r"(value), "r"(target)
00045                     : "cc", "memory");
00046        return ret;
00047     }
00048 
00049     public:
00050 
00051     inline static int32 Set (int32* target, int32 value)
00052     {
00053        while(Swpb(&AtomicLock, ~0) != 0);
00054        *target = value;
00055        Swpb(&AtomicLock, 0);
00056        return value;
00057     }
00058 
00059     inline static void* Set (void** target, void* value)
00060     {
00061        return (void*)Set ((int32*)target, (int32)value);
00062     }
00063 
00064     inline static int32 CompareAndSet (int32* target, int32 value,
00065       int32 comparand)
00066     {
00067 
00068        while(Swpb(&AtomicLock, ~0) != 0);
00069        int32 oldvalue = *target;
00070        if(*target == comparand)
00071          *target = value;
00072        Swpb(&AtomicLock, 0);
00073        return oldvalue;
00074     }
00075 
00076     inline static void* CompareAndSet (void** target, void* value,
00077       void* comparand)
00078     {
00079        return (void*)CompareAndSet ((int32*)target, (int32)value,
00080         (int32)comparand);
00081     }
00082 
00083     inline static int32 Increment (int32* target, register int32 incr = 1)
00084     {
00085        while(Swpb(&AtomicLock, ~0) != 0);
00086        *target += incr;
00087        int32 ret = *target;
00088        Swpb(&AtomicLock, 0);
00089        return ret;
00090     }
00091 
00092     inline static int32 Decrement (int32* target)
00093     {
00094        return (int32)Increment (target, -1);
00095     }
00096   };
00097 }
00098 }
00099 
00100 #endif // DOXYGEN_RUN
00101 
00102 #endif // __CS_CSUTIL_ATOMICOPS_GCC_ARM_H__

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