/usr/include/crystalspace-2.0/csutil/spinlock.h is in libcrystalspace-dev 2.0+dfsg-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Copyright (C) 2006 by Frank Richter
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef __CS_CSUTIL_SPINLOCK_H__
#define __CS_CSUTIL_SPINLOCK_H__
/**\file
*/
#ifndef CS_PLATFORM_WIN32
#include <pthread.h>
#include <sched.h>
#endif
/**\addtogroup util
* @{ */
namespace CS
{
class SpinLock
{
#ifdef CS_PLATFORM_WIN32
typedef DWORD ThreadID;
#else
typedef pthread_t ThreadID;
#endif
#if defined (CS_PROCESSOR_X86) && defined (CS_COMPILER_GCC)
volatile ThreadID threadid;
volatile uint l;
#elif defined(CS_PLATFORM_WIN32)
volatile ThreadID threadid;
volatile LONG l;
#else
pthread_mutex_t l;
#endif
volatile uint c;
static const int spinsPerYield = 63;
#if defined(CS_PLATFORM_WIN32)
CS_FORCEINLINE ThreadID CurrentThreadID()
{ return GetCurrentThreadId(); }
#else
CS_FORCEINLINE ThreadID CurrentThreadID()
{ return pthread_self(); }
#endif
// Spinlock implementation from ptmalloc3's malloc.c
#if defined (CS_PROCESSOR_X86) && defined (CS_COMPILER_GCC)
CS_FORCEINLINE bool DoLockWait()
{
ThreadID mythreadid = CurrentThreadID();
if(mythreadid == threadid)
++c;
else
{
int spins = 0;
for (;;) {
int ret;
__asm__ __volatile__ ("lock; cmpxchgl %2,(%1)" : "=a" (ret) : "r" (&l), "r" (1), "a" (0));
if(!ret)
{
CS_ASSERT(!threadid);
threadid = mythreadid;
c = 1;
break;
}
if ((++spins & spinsPerYield) == 0) {
#if defined(CS_PLATFORM_UNIX)
sched_yield();
#elif defined(CS_PLATFORM_WIN32)
SleepEx (0, FALSE);
#else /* no-op yield on unknown systems */
;
#endif /* CS_PLATFORM_UNIX, CS_PLATFORM_WIN32 */
}
}
}
return true;
}
CS_FORCEINLINE bool DoLockTry()
{
int ret;
__asm__ __volatile__ ("lock; cmpxchgl %2,(%1)" : "=a" (ret) : "r" (&l), "r" (1), "a" (0));
if(!ret){
CS_ASSERT(!threadid);
threadid = CurrentThreadID();
c=1;
return true;
}
return false;
}
CS_FORCEINLINE void DoRelease()
{
int ret;
CS_ASSERT(CurrentThreadID() == threadid);
if (!--c) {
threadid=0;
__asm__ __volatile__ ("xchgl %2,(%1)" : "=r" (ret) : "r" (&l), "0" (0));
}
}
CS_FORCEINLINE void Init() { threadid = 0; c = 0; l = 0; }
CS_FORCEINLINE void Destroy() {}
//------------------------------------------------------------------------
#elif defined(CS_PLATFORM_WIN32)
CS_FORCEINLINE bool DoLockWait()
{
ThreadID mythreadid = CurrentThreadID();
if(mythreadid == threadid)
++c;
else {
int spins = 0;
for (;;) {
if (!_InterlockedExchange(&l, 1)) {
CS_ASSERT(!threadid);
threadid = mythreadid;
c = 1;
break;
}
if ((++spins & spinsPerYield) == 0)
SleepEx (0, FALSE);
}
}
return true;
}
CS_FORCEINLINE bool DoLockTry()
{
if (!_InterlockedExchange (&l, 1)) {
CS_ASSERT (!threadid);
threadid = CurrentThreadID();
c = 1;
return true;
}
return false;
}
CS_FORCEINLINE void DoRelease()
{
CS_ASSERT (CurrentThreadID() == threadid);
if (!--c) {
threadid = 0;
_InterlockedExchange (&l, 0);
}
}
CS_FORCEINLINE void Init() { threadid = 0; c = 0; l = 0; }
CS_FORCEINLINE void Destroy() {}
//------------------------------------------------------------------------
#else
CS_FORCEINLINE bool DoLockWait()
{
if(!pthread_mutex_lock(&l)){
c++;
return true;
}
return false;
}
CS_FORCEINLINE bool DoLockTry()
{
if(!pthread_mutex_trylock(&l)){
c++;
return true;
}
return false;
}
CS_FORCEINLINE void DoRelease()
{
--c;
pthread_mutex_unlock(&l);
}
CS_FORCEINLINE void Init()
{
pthread_mutexattr_t attr;
c=0;
if(pthread_mutexattr_init (&attr)) return;
if(pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE)) return;
if(pthread_mutex_init (&l, &attr)) return;
pthread_mutexattr_destroy (&attr);
}
CS_FORCEINLINE void Destroy() {}
#endif
public:
SpinLock()
{ Init(); }
~SpinLock() { Destroy(); }
CS_FORCEINLINE bool LockWait()
{ return DoLockWait(); }
CS_FORCEINLINE bool LockTry()
{ return DoLockTry(); }
CS_FORCEINLINE void Release()
{ DoRelease(); }
};
} // namespace CS
/** @} */
#endif // __CS_CSUTIL_SPINLOCK_H__
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