Introduce USB MIDI descriptor parser
[chromium-blink-merge.git] / media / midi / usb_midi_descriptor_parser.cc
blobd454ff9469152c7fd9f39df314eaa2775b16a673
1 // Copyright 2014 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.
5 #include "media/midi/usb_midi_descriptor_parser.h"
7 #include <algorithm>
9 #include "base/logging.h"
11 namespace media {
13 namespace {
15 // The constants below are specified in USB spec, USB audio spec
16 // and USB midi spec.
18 enum DescriptorType {
19 TYPE_DEVICE = 1,
20 TYPE_CONFIGURATION = 2,
21 TYPE_STRING = 3,
22 TYPE_INTERFACE = 4,
23 TYPE_ENDPOINT = 5,
24 TYPE_DEVICE_QUALIFIER = 6,
25 TYPE_OTHER_SPEED_CONFIGURATION = 7,
26 TYPE_INTERFACE_POWER = 8,
28 TYPE_CS_INTERFACE = 36,
29 TYPE_CS_ENDPOINT = 37,
32 enum DescriptorSubType {
33 SUBTYPE_MS_DESCRIPTOR_UNDEFINED = 0,
34 SUBTYPE_MS_HEADER = 1,
35 SUBTYPE_MIDI_IN_JACK = 2,
36 SUBTYPE_MIDI_OUT_JACK = 3,
37 SUBTYPE_ELEMENT = 4,
40 enum JackType {
41 JACK_TYPE_UNDEFINED = 0,
42 JACK_TYPE_EMBEDDED = 1,
43 JACK_TYPE_EXTERNAL = 2,
46 const uint8 kAudioInterfaceClass = 1;
47 const uint8 kAudioMidiInterfaceSubclass = 3;
49 class JackMatcher {
50 public:
51 explicit JackMatcher(uint8 id) : id_(id) {}
53 bool operator() (const UsbMidiJack& jack) const {
54 return jack.jack_id == id_;
57 private:
58 uint8 id_;
61 } // namespace
63 UsbMidiDescriptorParser::UsbMidiDescriptorParser()
64 : is_parsing_usb_midi_interface_(false),
65 current_endpoint_address_(0),
66 current_cable_number_(0) {}
68 UsbMidiDescriptorParser::~UsbMidiDescriptorParser() {}
70 bool UsbMidiDescriptorParser::Parse(UsbMidiDevice* device,
71 const uint8* data,
72 size_t size,
73 std::vector<UsbMidiJack>* jacks) {
74 jacks->clear();
75 bool result = ParseInternal(device, data, size, jacks);
76 if (!result)
77 jacks->clear();
78 Clear();
79 return result;
82 bool UsbMidiDescriptorParser::ParseInternal(UsbMidiDevice* device,
83 const uint8* data,
84 size_t size,
85 std::vector<UsbMidiJack>* jacks) {
86 for (const uint8* current = data;
87 current < data + size;
88 current += current[0]) {
89 uint8 length = current[0];
90 if (length < 2) {
91 DVLOG(1) << "Descriptor Type is not accessible.";
92 return false;
94 if (current + length > data + size) {
95 DVLOG(1) << "The header size is incorrect.";
96 return false;
98 DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
99 if (descriptor_type != TYPE_INTERFACE && !is_parsing_usb_midi_interface_)
100 continue;
102 switch (descriptor_type) {
103 case TYPE_INTERFACE:
104 if (!ParseInterface(current, length))
105 return false;
106 break;
107 case TYPE_CS_INTERFACE:
108 // We are assuming that the corresponding INTERFACE precedes
109 // the CS_INTERFACE descriptor, as specified.
110 if (!ParseCSInterface(device, current, length))
111 return false;
112 break;
113 case TYPE_ENDPOINT:
114 // We are assuming that endpoints are contained in an interface.
115 if (!ParseEndpoint(current, length))
116 return false;
117 break;
118 case TYPE_CS_ENDPOINT:
119 // We are assuming that the corresponding ENDPOINT precedes
120 // the CS_ENDPOINT descriptor, as specified.
121 if (!ParseCSEndpoint(current, length, jacks))
122 return false;
123 break;
124 default:
125 // Ignore uninteresting types.
126 break;
129 return true;
132 bool UsbMidiDescriptorParser::ParseInterface(const uint8* data, size_t size) {
133 if (size != 9) {
134 DVLOG(1) << "INTERFACE header size is incorrect.";
135 return false;
137 incomplete_jacks_.clear();
139 uint8 interface_class = data[5];
140 uint8 interface_subclass = data[6];
142 // All descriptors of endpoints contained in this interface
143 // precede the next INTERFACE descriptor.
144 is_parsing_usb_midi_interface_ =
145 interface_class == kAudioInterfaceClass &&
146 interface_subclass == kAudioMidiInterfaceSubclass;
147 return true;
150 bool UsbMidiDescriptorParser::ParseCSInterface(UsbMidiDevice* device,
151 const uint8* data,
152 size_t size) {
153 // Descriptor Type and Descriptor Subtype should be accessible.
154 if (size < 3) {
155 DVLOG(1) << "CS_INTERFACE header size is incorrect.";
156 return false;
159 DescriptorSubType subtype = static_cast<DescriptorSubType>(data[2]);
161 if (subtype != SUBTYPE_MIDI_OUT_JACK &&
162 subtype != SUBTYPE_MIDI_IN_JACK)
163 return true;
165 if (size < 6) {
166 DVLOG(1) << "CS_INTERFACE (MIDI JACK) header size is incorrect.";
167 return false;
169 uint8 jack_type = data[3];
170 uint8 id = data[4];
171 if (jack_type == JACK_TYPE_EMBEDDED) {
172 // We can't determine the associated endpoint now.
173 incomplete_jacks_.push_back(UsbMidiJack(device, id, 0, 0));
175 return true;
178 bool UsbMidiDescriptorParser::ParseEndpoint(const uint8* data, size_t size) {
179 if (size < 4) {
180 DVLOG(1) << "ENDPOINT header size is incorrect.";
181 return false;
183 current_endpoint_address_ = data[2];
184 current_cable_number_ = 0;
185 return true;
188 bool UsbMidiDescriptorParser::ParseCSEndpoint(const uint8* data,
189 size_t size,
190 std::vector<UsbMidiJack>* jacks) {
191 const size_t kSizeForEmptyJacks = 4;
192 // CS_ENDPOINT must be of size 4 + n where n is the number of associated
193 // jacks.
194 if (size < kSizeForEmptyJacks) {
195 DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
196 return false;
198 uint8 num_jacks = data[3];
199 if (size != kSizeForEmptyJacks + num_jacks) {
200 DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
201 return false;
204 for (size_t i = 0; i < num_jacks; ++i) {
205 uint8 jack = data[kSizeForEmptyJacks + i];
206 std::vector<UsbMidiJack>::iterator it =
207 std::find_if(incomplete_jacks_.begin(),
208 incomplete_jacks_.end(),
209 JackMatcher(jack));
210 if (it == incomplete_jacks_.end()) {
211 DVLOG(1) << "A non-existing MIDI jack is associated.";
212 return false;
214 if (current_cable_number_ > 0xf) {
215 DVLOG(1) << "Cable number should range from 0x0 to 0xf.";
216 return false;
218 // CS_ENDPOINT follows ENDPOINT and hence we can use the following
219 // member variables.
220 it->cable_number = current_cable_number_++;
221 it->endpoint_address = current_endpoint_address_;
222 jacks->push_back(*it);
223 incomplete_jacks_.erase(it);
225 return true;
228 void UsbMidiDescriptorParser::Clear() {
229 is_parsing_usb_midi_interface_ = false;
230 current_endpoint_address_ = 0;
231 current_cable_number_ = 0;
232 incomplete_jacks_.clear();
235 } // namespace media