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1 // Copyright 2013 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 #include "media/midi/message_util.h" | |
6 | |
7 #include "base/logging.h" | |
8 #include "base/metrics/histogram_macros.h" | |
9 | |
10 namespace midi { | |
11 | |
12 size_t GetMessageLength(uint8_t status_byte) { | |
13 if (status_byte < 0x80) | |
14 return 0; | |
15 if (0x80 <= status_byte && status_byte <= 0xbf) | |
16 return 3; | |
17 if (0xc0 <= status_byte && status_byte <= 0xdf) | |
18 return 2; | |
19 if (0xe0 <= status_byte && status_byte <= 0xef) | |
20 return 3; | |
21 | |
22 switch (status_byte) { | |
23 case 0xf0: | |
24 return 0; | |
25 case 0xf1: | |
26 return 2; | |
27 case 0xf2: | |
28 return 3; | |
29 case 0xf3: | |
30 return 2; | |
31 case 0xf4: // Reserved | |
32 case 0xf5: // Reserved | |
33 return 0; | |
34 case 0xf6: | |
35 return 1; | |
36 case 0xf7: | |
37 return 0; | |
38 case 0xf8: | |
39 case 0xf9: | |
40 case 0xfa: | |
41 case 0xfb: | |
42 case 0xfc: | |
43 case 0xfd: | |
44 case 0xfe: | |
45 case 0xff: | |
46 return 1; | |
47 default: | |
48 NOTREACHED(); | |
49 return 0; | |
50 } | |
51 } | |
52 | |
53 bool IsDataByte(uint8_t data) { | |
54 return (data & 0x80) == 0; | |
55 } | |
56 | |
57 bool IsSystemRealTimeMessage(uint8_t data) { | |
58 return 0xf8 <= data; | |
59 } | |
60 | |
61 bool IsSystemMessage(uint8_t data) { | |
62 return 0xf0 <= data; | |
63 } | |
64 | |
65 bool IsValidWebMIDIData(const std::vector<uint8_t>& data) { | |
66 bool in_sysex = false; | |
67 size_t sysex_start_offset = 0; | |
68 size_t waiting_data_length = 0; | |
69 for (size_t i = 0; i < data.size(); ++i) { | |
70 const uint8_t current = data[i]; | |
71 if (IsSystemRealTimeMessage(current)) | |
72 continue; // Real time message can be placed at any point. | |
73 if (waiting_data_length > 0) { | |
74 if (!IsDataByte(current)) | |
75 return false; // Error: |current| should have been data byte. | |
76 --waiting_data_length; | |
77 continue; // Found data byte as expected. | |
78 } | |
79 if (in_sysex) { | |
80 if (data[i] == kEndOfSysExByte) { | |
81 in_sysex = false; | |
82 UMA_HISTOGRAM_COUNTS("Media.Midi.SysExMessageSizeUpTo1MB", | |
83 i - sysex_start_offset + 1); | |
84 } else if (!IsDataByte(current)) { | |
85 return false; // Error: |current| should have been data byte. | |
86 } | |
87 continue; // Found data byte as expected. | |
88 } | |
89 if (current == kSysExByte) { | |
90 in_sysex = true; | |
91 sysex_start_offset = i; | |
92 continue; // Found SysEX | |
93 } | |
94 waiting_data_length = midi::GetMessageLength(current); | |
yukawa
2016/10/19 20:11:20
Can we drop midi:: ?
waiting_data_length = G
Takashi Toyoshima
2016/10/20 05:18:17
Done.
| |
95 if (waiting_data_length == 0) | |
96 return false; // Error: |current| should have been a valid status byte. | |
97 --waiting_data_length; // Found status byte | |
98 } | |
99 return waiting_data_length == 0 && !in_sysex; | |
100 } | |
101 | |
102 } // namespace midi | |
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