AtomicInt32.h

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#ifndef G3D_ATOMICINT32_H
#define G3D_ATOMICINT32_H

#include "G3D/platform.h"
#include "G3D/g3dmath.h"

#if defined(G3D_OSX)
# include <libkern/OSAtomic.h>
#endif

namespace G3D {

class AtomicInt32 {
private:
# if defined(G3D_WINDOWS) 
 volatile long m_value;
# elif defined(G3D_OSX)
 int32_t m_value;
# else
 volatile int32 m_value;
# endif


public:

 AtomicInt32() {}

 explicit AtomicInt32(const int32 x) {
 m_value = x;
 }

 AtomicInt32(const AtomicInt32& x) {
 m_value = x.m_value;
 }

 const AtomicInt32& operator=(const int32 x) {
 m_value = x;
 return *this;
 }

 void operator=(const AtomicInt32& x) {
 m_value = x.m_value;
 }

 int32 value() const {
 return m_value;
 }

 int32 add(const int32 x) {
# if defined(G3D_WINDOWS)

 return InterlockedExchangeAdd(&m_value, x);

# elif defined(G3D_LINUX) || defined(G3D_FREEBSD)

 int32 old;
 asm volatile ("lock; xaddl %0,%1"
 : "=r"(old), "=m"(m_value) /* outputs */
 : "0"(x), "m"(m_value) /* inputs */
 : "memory", "cc");
 return old;
 
# elif defined(G3D_OSX)

 int32 old = m_value;
 OSAtomicAdd32(x, &m_value);
 return old;

# endif
 }

 int32 sub(const int32 x) {
 return add(-x);
 }

 void increment() {
# if defined(G3D_WINDOWS)
 // Note: returns the newly incremented value
 InterlockedIncrement(&m_value);
# elif defined(G3D_LINUX) || defined(G3D_FREEBSD)
 add(1);
# elif defined(G3D_OSX)
 // Note: returns the newly incremented value
 OSAtomicIncrement32(&m_value);
# endif
 }

 int32 decrement() {
# if defined(G3D_WINDOWS)
 // Note: returns the newly decremented value
 return InterlockedDecrement(&m_value);
# elif defined(G3D_LINUX) || defined(G3D_FREEBSD)
 unsigned char nz;

 asm volatile ("lock; decl %1;\n\t"
 "setnz %%al"
 : "=a" (nz)
 : "m" (m_value)
 : "memory", "cc");
 return nz;
# elif defined(G3D_OSX)
 // Note: returns the newly decremented value
 return OSAtomicDecrement32(&m_value);
# endif
 }


 int32 compareAndSet(const int32 comperand, const int32 exchange) {
# if defined(G3D_WINDOWS)
 return InterlockedCompareExchange(&m_value, exchange, comperand);
# elif defined(G3D_LINUX) || defined(G3D_FREEBSD) || defined(G3D_OSX)
 // Based on Apache Portable Runtime
 // http://koders.com/c/fid3B6631EE94542CDBAA03E822CA780CBA1B024822.aspx
 int32 ret;
 asm volatile ("lock; cmpxchgl %1, %2"
 : "=a" (ret)
 : "r" (exchange), "m" (m_value), "0"(comperand)
 : "memory", "cc");
 return ret;

 // Note that OSAtomicCompareAndSwap32 does not return a useful value for us
 // so it can't satisfy the cmpxchgl contract.
# endif
 }

};

} // namespace

#endif