Add base/memory.h.

/*

 * Copyright (C) 2015 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef BASE_MEMORY_H

#define BASE_MEMORY_H

namespace android {

namespace base {

// Use packed structures for access to unaligned data on targets with alignment

// restrictions.  The compiler will generate appropriate code to access these

// structures without generating alignment exceptions.

template <typename T>

static inline T get_unaligned(const T* address) {

  struct unaligned {

    T v;

  } __attribute__((packed));

  const unaligned* p = reinterpret_cast<const unaligned*>(address);

  return p->v;

}

template <typename T>

static inline void put_unaligned(T* address, T v) {

  struct unaligned {

    T v;

  } __attribute__((packed));

  unaligned* p = reinterpret_cast<unaligned*>(address);

  p->v = v;

}

} // namespace base

} // namespace android

#endif // BASE_MEMORY_H