1/*
2 * Copyright (c) 2023 Shenzhen Kaihong Digital Industry Development 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#include "h264_frame.h"
17#include "common/common_macro.h"
18#include "common/sharing_log.h"
19
20namespace OHOS {
21namespace Sharing {
22size_t PrefixSize(const char *ptr, size_t len)
23{
24    if (ptr == nullptr) {
25        return 0;
26    }
27
28    if (len < 4) { // 4:byte offset
29        return 0;
30    }
31    if (ptr[0] != 0x00 || ptr[1] != 0x00) {
32        return 0;
33    }
34    if (ptr[2] == 0x00 && ptr[3] == 0x01) { // 2:byte offset, 3:byte offset
35        return 4;                           // 4:prefix size
36    }
37    if (ptr[2] == 0x01) { // 2:byte offset
38        return 3;         // 3:prefix size
39    }
40
41    return 0;
42}
43
44static const char *MemFind(const char *buf, ssize_t len, const char *subBuf, ssize_t subLen)
45{
46    if (buf == nullptr || subBuf == nullptr) {
47        return NULL;
48    }
49
50    for (auto i = 0; i < len - subLen; ++i) {
51        if (memcmp(buf + i, subBuf, subLen) == 0) {
52            return buf + i;
53        }
54    }
55
56    return NULL;
57}
58
59void SplitH264(const char *ptr, size_t len, size_t prefix, const std::function<void(const char *, size_t, size_t)> &cb)
60{
61    RETURN_IF_NULL(ptr);
62    if (prefix <= 0) {
63        prefix = PrefixSize(ptr, len);
64    }
65    auto start = ptr + prefix;
66    auto end = ptr + len;
67    size_t nextPrefix;
68    while (true) {
69        auto nextStart = MemFind(start, end - start, "\x00\x00\x01", 3);
70        if (nextStart) {
71            if (*(nextStart - 1) == 0x00) {
72                nextStart -= 1;
73                nextPrefix = 4; // 4:prefix size
74            } else {
75                nextPrefix = 3; // 3:prefix size
76            }
77
78            cb(start - prefix, nextStart - start + prefix, prefix);
79
80            start = nextStart + nextPrefix;
81
82            prefix = nextPrefix;
83            continue;
84        }
85
86        cb(start - prefix, end - start + prefix, prefix);
87        break;
88    }
89}
90} // namespace Sharing
91} // namespace OHOS