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/********************************************************************************
* *
* S p i n l o c k C l a s s *
* *
*********************************************************************************
* Copyright (C) 2004,2022 by Jeroen van der Zijp. All Rights Reserved. *
*********************************************************************************
* This library is free software; you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as published by *
* the Free Software Foundation; either version 3 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 Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/> *
********************************************************************************/
#include "xincs.h"
#include "fxver.h"
#include "fxdefs.h"
#include "FXSpinLock.h"
/*
Notes:
- Spin lock variable.
- Extra fluff data is not useless; it is intentionally there to pad the
spin-variable to a cache line, thus reducing false-sharing in case other
"hot" data is nearby.
- Ticket spinlock flavor does not support more than 256 simultaneous threads.
*/
using namespace FX;
/*******************************************************************************/
namespace FX {
// Initialize spinlock
FXSpinLock::FXSpinLock(){
#if defined(WIN32)
data[0]=data[1]=data[2]=data[3]=0;
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
data[0]=data[1]=data[2]=data[3]=0;
#elif defined(__APPLE__)
// If this fails on your machine, determine what value
// of sizeof(pthread_mutex_t) is supposed to be on your
// machine and mail it to: jeroen@fox-toolkit.net!!
//FXTRACE((150,"sizeof(OSSpinLock)=%d\n",sizeof(OSSpinLock)));
FXASSERT_STATIC(sizeof(data)>=sizeof(OSSpinLock));
data[0]=data[1]=data[2]=data[3]=0;
*((OSSpinLock*)data)=OS_SPINLOCK_INIT;
#else
// If this fails on your machine, determine what value
// of sizeof(pthread_spinlock_t) is supposed to be on your
// machine and mail it to: jeroen@fox-toolkit.net!!
//FXTRACE((150,"sizeof(pthread_spinlock_t)=%d\n",sizeof(pthread_spinlock_t)));
FXASSERT_STATIC(sizeof(data)>=sizeof(pthread_spinlock_t));
data[0]=data[1]=data[2]=data[3]=0;
pthread_spin_init((pthread_spinlock_t*)(void*)data,PTHREAD_PROCESS_PRIVATE);
#endif
}
// Lock the spinlock
void FXSpinLock::lock(){
#if defined(WIN32)
while(_InterlockedExchange((LONG*)data,1L)){
YieldProcessor();
}
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
__asm__ __volatile__ ("movw $0x0100, %%ax \n\t"
"lock\n\t"
"xaddw %%ax, %0 \n\t"
"1: \n\t"
"cmpb %%ah, %%al\n\t"
"je 2f\n\t"
"rep; nop\n\t"
"movb %0, %%al\n\t"
"jmp 1b\n\t"
"2:" : "+m" (data) : : "memory", "ax", "cc");
#elif defined(__APPLE__)
OSSpinLockLock((OSSpinLock*)data);
#else
pthread_spin_lock((pthread_spinlock_t*)(void*)data);
#endif
}
// Try lock the spinlock
FXbool FXSpinLock::trylock(){
#if defined(WIN32)
return !_InterlockedExchange((LONG*)data,1L);
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
FXbool ret;
__asm__ __volatile__ ("movw %1,%%ax\n\t"
"cmpb %%ah, %%al\n\t"
"jne 1f\n\t"
"movw %%ax,%%cx\n\t"
"addw $0x0100,%%cx\n\t"
"lock\n\t"
"cmpxchgw %%cx,%1\n\t"
"1:\n\t"
"sete %b0\n\t" :"=a" (ret), "+m" (data) : : "ecx", "memory", "cc");
return ret;
#elif defined(__APPLE__)
return OSSpinLockTry((OSSpinLock*)data);
#else
return pthread_spin_trylock((pthread_spinlock_t*)(void*)data)==0;
#endif
}
// Unlock spinlock
void FXSpinLock::unlock(){
#if defined(WIN32)
_InterlockedExchange((LONG*)data,0L);
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
__asm__ __volatile__ ("lock\n\t"
"incb %0\n\t" : "+m" (data) : : "memory", "cc");
#elif defined(__APPLE__)
OSSpinLockUnlock((OSSpinLock*)data);
#else
pthread_spin_unlock((pthread_spinlock_t*)(void*)data);
#endif
}
// Test if locked
FXbool FXSpinLock::locked(){
#if defined(WIN32)
return (data[0]!=0);
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
FXbool ret;
__asm__ __volatile__ ("movw %1,%%ax\n\t"
"cmpb %%ah, %%al\n\t"
"setne %%al\n\t" :"=a" (ret), "+m" (data) : : "memory", "cc");
return ret;
#elif defined(__APPLE__)
if(OSSpinLockTry((OSSpinLock*)data)){
OSSpinLockUnlock((OSSpinLock*)data);
return false;
}
return true;
#else
if(pthread_spin_trylock((pthread_spinlock_t*)(void*)data)==0){
pthread_spin_unlock((pthread_spinlock_t*)(void*)data);
return false;
}
return true;
#endif
}
// Delete spinlock
FXSpinLock::~FXSpinLock(){
#if defined(WIN32)
// NOP //
#elif (defined(__GNUC__) || defined(__INTEL_COMPILER)) && (defined(__i386__) || defined(__x86_64__))
// NOP //
#elif defined(__APPLE__)
// NOP //
#else
pthread_spin_destroy((pthread_spinlock_t*)(void*)data);
#endif
}
}
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