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/*
Copyright (c) 2009-2012 250bpm s.r.o.
Copyright (c) 2007-2009 iMatix Corporation
Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
This file is part of Crossroads I/O project.
Crossroads I/O 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.
Crossroads 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/>.
*/
#ifndef __XS_ATOMIC_COUNTER_HPP_INCLUDED__
#define __XS_ATOMIC_COUNTER_HPP_INCLUDED__
#include "stdint.hpp"
#include "platform.hpp"
#if defined XS_FORCE_MUTEXES
#define XS_ATOMIC_COUNTER_MUTEX
#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
#define XS_ATOMIC_COUNTER_X86
#elif defined XS_HAVE_WINDOWS
#define XS_ATOMIC_COUNTER_WINDOWS
#elif (defined XS_HAVE_SOLARIS || defined XS_HAVE_NETBSD)
#define XS_ATOMIC_COUNTER_ATOMIC_H
#else
#define XS_ATOMIC_COUNTER_MUTEX
#endif
#if defined XS_ATOMIC_COUNTER_MUTEX
#include "mutex.hpp"
#elif defined XS_ATOMIC_COUNTER_WINDOWS
#include "windows.hpp"
#elif defined XS_ATOMIC_COUNTER_ATOMIC_H
#include <atomic.h>
#endif
namespace xs
{
// This class represents an integer that can be incremented/decremented
// in atomic fashion.
class atomic_counter_t
{
public:
typedef uint32_t integer_t;
inline atomic_counter_t (integer_t value_ = 0) :
value (value_)
{
}
inline ~atomic_counter_t ()
{
}
// Set counter value (not thread-safe).
inline void set (integer_t value_)
{
value = value_;
}
// Atomic addition. Returns the old value.
inline integer_t add (integer_t increment_)
{
integer_t old_value;
#if defined XS_ATOMIC_COUNTER_WINDOWS
old_value = InterlockedExchangeAdd ((LONG*) &value, increment_);
#elif defined XS_ATOMIC_COUNTER_ATOMIC_H
integer_t new_value = atomic_add_32_nv (&value, increment_);
old_value = new_value - increment_;
#elif defined XS_ATOMIC_COUNTER_X86
__asm__ volatile (
"lock; xadd %0, %1 \n\t"
: "=r" (old_value), "=m" (value)
: "0" (increment_), "m" (value)
: "cc", "memory");
#elif defined XS_ATOMIC_COUNTER_MUTEX
sync.lock ();
old_value = value;
value += increment_;
sync.unlock ();
#else
#error atomic_counter is not implemented for this platform
#endif
return old_value;
}
// Atomic subtraction. Returns false if the counter drops to zero.
inline bool sub (integer_t decrement)
{
#if defined XS_ATOMIC_COUNTER_WINDOWS
LONG delta = - ((LONG) decrement);
integer_t old = InterlockedExchangeAdd ((LONG*) &value, delta);
return old - decrement != 0;
#elif defined XS_ATOMIC_COUNTER_ATOMIC_H
int32_t delta = - ((int32_t) decrement);
integer_t nv = atomic_add_32_nv (&value, delta);
return nv != 0;
#elif defined XS_ATOMIC_COUNTER_X86
integer_t oldval = -decrement;
volatile integer_t *val = &value;
__asm__ volatile ("lock; xaddl %0,%1"
: "=r" (oldval), "=m" (*val)
: "0" (oldval), "m" (*val)
: "cc", "memory");
return oldval != decrement;
#elif defined XS_ATOMIC_COUNTER_MUTEX
sync.lock ();
value -= decrement;
bool result = value ? true : false;
sync.unlock ();
return result;
#else
#error atomic_counter is not implemented for this platform
#endif
}
inline integer_t get ()
{
return value;
}
private:
volatile integer_t value;
#if defined XS_ATOMIC_COUNTER_MUTEX
mutex_t sync;
#endif
atomic_counter_t (const atomic_counter_t&);
const atomic_counter_t& operator = (const atomic_counter_t&);
};
}
// Remove macros local to this file.
#if defined XS_ATOMIC_COUNTER_WINDOWS
#undef XS_ATOMIC_COUNTER_WINDOWS
#endif
#if defined XS_ATOMIC_COUNTER_ATOMIC_H
#undef XS_ATOMIC_COUNTER_ATOMIC_H
#endif
#if defined XS_ATOMIC_COUNTER_X86
#undef XS_ATOMIC_COUNTER_X86
#endif
#if defined XS_ATOMIC_COUNTER_MUTEX
#undef XS_ATOMIC_COUNTER_MUTEX
#endif
#endif
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