system_wrappers/interface/aligned_malloc.h

/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_ALIGNED_MALLOC_H_
#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_ALIGNED_MALLOC_H_

// The functions declared here
// 1) Allocates block of aligned memory.
// 2) Re-calculates a pointer such that it is aligned to a higher or equal
//    address.
// Note: alignment must be a power of two. The alignment is in bytes.

#include <stddef.h>

#include "system_wrappers/interface/scoped_ptr.h"

namespace webrtc {

// Returns a pointer to the first boundry of |alignment| bytes following the
// address of |ptr|.
// Note that there is no guarantee that the memory in question is available.
// |ptr| has no requirements other than it can't be NULL.
void* GetRightAlign(const void* ptr, size_t alignment);

// Allocates memory of |size| bytes aligned on an |alignment| boundry.
// The return value is a pointer to the memory. Note that the memory must
// be de-allocated using AlignedFree.
void* AlignedMalloc(size_t size, size_t alignment);
// De-allocates memory created using the AlignedMalloc() API.
void AlignedFree(void* mem_block);

// Templated versions to facilitate usage of aligned malloc without casting
// to and from void*.
template<typename T>
T* GetRightAlign(const T* ptr, size_t alignment) {
  return reinterpret_cast<T*>(GetRightAlign(reinterpret_cast<const void*>(ptr),
                                            alignment));
}
template<typename T>
T* AlignedMalloc(size_t size, size_t alignment) {
  return reinterpret_cast<T*>(AlignedMalloc(size, alignment));
}

// Scoped pointer to AlignedMalloc-memory.
template<typename T>
struct Allocator {
  typedef scoped_ptr_malloc<T, AlignedFree> scoped_ptr_aligned;
};

}  // namespace webrtc

#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_ALIGNED_MALLOC_H_