1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_
6#define PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_
7
8#include <limits>
9
10#include "base/basictypes.h"
11#include "ppapi/shared_impl/ppapi_shared_export.h"
12
13namespace ppapi {
14
15enum PPIdType {
16  PP_ID_TYPE_MODULE,
17  PP_ID_TYPE_INSTANCE,
18  PP_ID_TYPE_RESOURCE,
19  PP_ID_TYPE_VAR,
20
21  // Not a real type, must be last.
22  PP_ID_TYPE_COUNT
23};
24
25PPAPI_SHARED_EXPORT extern const unsigned int kPPIdTypeBits;
26
27extern const int32 kMaxPPId;
28
29// The least significant bits are the type, the rest are the value.
30template <typename T>
31inline T MakeTypedId(T value, PPIdType type) {
32  return (value << kPPIdTypeBits) | static_cast<T>(type);
33}
34
35template <typename T>
36inline bool CheckIdType(T id, PPIdType type) {
37  // Say a resource of 0 is always valid, since that means "no resource."
38  // You shouldn't be passing 0 var, instance, or module IDs around so those
39  // are still invalid.
40  if (type == PP_ID_TYPE_RESOURCE && !id)
41    return true;
42  const T mask = (static_cast<T>(1) << kPPIdTypeBits) - 1;
43  return (id & mask) == type;
44}
45
46}  // namespace ppapi
47
48#endif  // PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_
49