Atomicity encapsulation for android arm devices.

armv6_atomic

#ifndef _VISION_PLAY_ARMV6_ATOMIC_H_
#define _VISION_PLAY_ARMV6_ATOMIC_H_

#if defined(__ARMEL__) &&  defined(__linux__)

typedef void (*LinuxKernelMemoryBarrierFunc)(void);

// Using the highly optimized device-specific memory barrier function.
inline void MemoryBarrier() {
  (*(LinuxKernelMemoryBarrierFunc)0xffff0fa0)();
}

#else
//# error Not on Android ARM linux devices.
// Make a compiler error here
int a[-1];
#endif

namespace visionplay {

// @class A templated atomicity encapsulation.
// T should be POD type, as simple as possible.
// Best practice is using char, int, void* only.
template <typename T>
class Atomic {
 public:
  Atomic() : value_((T)0) {}
  explicit Atomic(const T& t) : value_(t) {}
  T NoBarrier_Load() const {return value_;}
  void NoBarrier_Store(const T& t) {value_ = t;}
  T Acquire_Load() const {
    T res = value_;
    MemoryBarrier();
    return res;
  }
  void Release_Store(const T& t) {
    MemoryBarrier();
    value_ = t;
  }
 private:
  T value_;
};


}  // namespace visionplay

#endif  // _VISION_PLAY_ARMV6_ATOMIC_H_