1/*
2 * Copyright (C) 2023 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 *     http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16#ifndef OHOS_MEDIA_AV_SHARED_MEMORY_H
17#define OHOS_MEDIA_AV_SHARED_MEMORY_H
18
19#ifndef MEDIA_NO_OHOS
20#ifndef MEDIA_OHOS
21#define MEDIA_OHOS
22#endif
23#else
24#ifdef MEDIA_OHOS
25#undef MEDIA_OHOS
26#endif
27#endif
28
29#include <memory>
30#include <string>
31
32namespace OHOS {
33namespace Media {
34/**
35 * @brief Provides a unified interface to implement convenient memory sharing
36 * mechanism. For those platforms that do not support multi-process, it may
37 * simply encapsulate ordinary memory blocks, not really multi-process shareable memory.
38 */
39class __attribute__((visibility("default"))) AVSharedMemory {
40public:
41    virtual ~AVSharedMemory() = default;
42
43    /**
44     * @brief Enumerates the flag bits used to create a new shared memory.
45     */
46    enum Flags : uint32_t {
47        /**
48         * This flag bit indicates that the remote process is allowed to read and write
49         * the shared memory. If no flags are specified, this is the default memory
50         * sharing policy. If the FLAGS_READ_ONLY bit is set, this flag bit is ignored.
51         */
52        FLAGS_READ_WRITE = 0x1,
53        /**
54         * For platforms that support multiple processes, this flag bit indicates that the
55         * remote process can only read data in the shared memory. If this flag is not set,
56         * the remote process has both read and write permissions by default. Adding this
57         * flag does not affect the process that creates the memory, which always has the
58         * read and write permission on the shared memory. For platforms that do not support
59         * multi-processes, the memory read and write permission control capability may
60         * not be available. In this case, this flag is invalid.
61         */
62        FLAGS_READ_ONLY = 0x2,
63    };
64
65    /**
66     * @brief Get the memory's virtual address
67     * @return the memory's virtual address if the memory is valid, otherwise nullptr.
68     */
69    virtual uint8_t *GetBase() const = 0;
70
71    /**
72     * @brief Get the memory's size
73     * @return the memory's size if the memory is valid, otherwise -1.
74     */
75    virtual int32_t GetSize() const = 0;
76
77    /**
78     * @brief Get the memory's flags set by the creator, refer to {@Flags}
79     * @return the memory's flags if the memory is valid, otherwise 0.
80     */
81    virtual uint32_t GetFlags() const = 0;
82};
83} // namespace Media
84} // namespace OHOS
85#endif // AVSHAREDMEMORY_H