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+/*
+ Copyright (c) 2007-2010 iMatix Corporation
+
+ This file is part of 0MQ.
+
+ 0MQ is free software; you can redistribute it and/or modify it under
+ the terms of the Lesser GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ 0MQ 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
+ Lesser GNU General Public License for more details.
+
+ You should have received a copy of the Lesser GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_ATOMIC_COUNTER_HPP_INCLUDED__
+#define __ZMQ_ATOMIC_COUNTER_HPP_INCLUDED__
+
+#include "stdint.hpp"
+#include "platform.hpp"
+
+#if defined ZMQ_FORCE_MUTEXES
+#define ZMQ_ATOMIC_COUNTER_MUTEX
+#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
+#define ZMQ_ATOMIC_COUNTER_X86
+#elif defined ZMQ_HAVE_WINDOWS
+#define ZMQ_ATOMIC_COUNTER_WINDOWS
+#elif (defined ZMQ_HAVE_SOLARIS || defined ZMQ_HAVE_NETBSD)
+#define ZMQ_ATOMIC_COUNTER_ATOMIC_H
+#else
+#define ZMQ_ATOMIC_COUNTER_MUTEX
+#endif
+
+#if defined ZMQ_ATOMIC_COUNTER_MUTEX
+#include "mutex.hpp"
+#elif defined ZMQ_ATOMIC_COUNTER_WINDOWS
+#include "windows.hpp"
+#elif defined ZMQ_ATOMIC_COUNTER_ATOMIC_H
+#include <atomic.h>
+#endif
+
+namespace zmq
+{
+
+ // 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 ZMQ_ATOMIC_COUNTER_WINDOWS
+ old_value = InterlockedExchangeAdd ((LONG*) &value, increment_);
+#elif defined ZMQ_ATOMIC_COUNTER_ATOMIC_H
+ integer_t new_value = atomic_add_32_nv (&value, increment_);
+ old_value = new_value - increment_;
+#elif defined ZMQ_ATOMIC_COUNTER_X86
+ __asm__ volatile (
+ "lock; xadd %0, %1 \n\t"
+ : "=r" (old_value), "=m" (value)
+ : "0" (increment_), "m" (value)
+ : "cc", "memory");
+#elif defined ZMQ_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 ZMQ_ATOMIC_COUNTER_WINDOWS
+ LONG delta = - ((LONG) decrement);
+ integer_t old = InterlockedExchangeAdd ((LONG*) &value, delta);
+ return old - decrement != 0;
+#elif defined ZMQ_ATOMIC_COUNTER_ATOMIC_H
+ int32_t delta = - ((int32_t) decrement);
+ integer_t nv = atomic_add_32_nv (&value, delta);
+ return nv != 0;
+#elif defined ZMQ_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 ZMQ_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 ZMQ_ATOMIC_COUNTER_MUTEX
+ mutex_t sync;
+#endif
+
+ atomic_counter_t (const atomic_counter_t&);
+ void operator = (const atomic_counter_t&);
+ };
+
+}
+
+// Remove macros local to this file.
+#if defined ZMQ_ATOMIC_COUNTER_WINDOWS
+#undef ZMQ_ATOMIC_COUNTER_WINDOWS
+#endif
+#if defined ZMQ_ATOMIC_COUNTER_ATOMIC_H
+#undef ZMQ_ATOMIC_COUNTER_ATOMIC_H
+#endif
+#if defined ZMQ_ATOMIC_COUNTER_X86
+#undef ZMQ_ATOMIC_COUNTER_X86
+#endif
+#if defined ZMQ_ATOMIC_COUNTER_MUTEX
+#undef ZMQ_ATOMIC_COUNTER_MUTEX
+#endif
+
+#endif
+