media/midi/usb_midi_output_stream.cc

   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.
   4
   5 #include "media/midi/usb_midi_output_stream.h"
   6
   7 #include "base/logging.h"
   8 #include "media/midi/midi_message_util.h"
   9 #include "media/midi/usb_midi_device.h"
  10
  11 namespace media {
  12
  13 UsbMidiOutputStream::UsbMidiOutputStream(const UsbMidiJack& jack)
  14     : jack_(jack), pending_size_(0), is_sending_sysex_(false) {}
  15
  16 void UsbMidiOutputStream::Send(const std::vector<uint8>& data) {
  17   // To prevent link errors caused by DCHECK_*.
  18   const size_t kPacketContentSize = UsbMidiOutputStream::kPacketContentSize;
  19   DCHECK_LT(jack_.cable_number, 16u);
  20
  21   std::vector<uint8> data_to_send;
  22   size_t current = 0;
  23   size_t size = GetSize(data);
  24   while (current < size) {
  25     uint8 first_byte = Get(data, current);
  26     if (first_byte == kSysExByte || is_sending_sysex_) {
  27       // System Exclusive messages
  28       if (!PushSysExMessage(data, &current, &data_to_send))
  29         break;
  30     } else if ((first_byte & kSysMessageBitMask) == kSysMessageBitPattern) {
  31       if (first_byte & 0x08) {
  32         // System Real-Time messages
  33         PushSysRTMessage(data, &current, &data_to_send);
  34       } else {
  35         // System Common messages
  36         if (!PushSysCommonMessage(data, &current, &data_to_send))
  37           break;
  38       }
  39     } else if (first_byte & 0x80) {
  40       if (!PushChannelMessage(data, &current, &data_to_send))
  41         break;
  42     } else {
  43       // Unknown messages
  44       DVLOG(1) << "Unknown byte: " << static_cast<unsigned int>(first_byte);
  45       ++current;
  46     }
  47   }
  48
  49   if (data_to_send.size() > 0)
  50     jack_.device->Send(jack_.endpoint_number(), data_to_send);
  51
  52   DCHECK_LE(current, size);
  53   DCHECK_LE(size - current, kPacketContentSize);
  54   // Note that this can be a self-copying and the iteration order is important.
  55   for (size_t i = current; i < size; ++i)
  56     pending_data_[i - current] = Get(data, i);
  57   pending_size_ = size - current;
  58 }
  59
  60 size_t UsbMidiOutputStream::GetSize(const std::vector<uint8>& data) const {
  61   return data.size() + pending_size_;
  62 }
  63
  64 uint8_t UsbMidiOutputStream::Get(const std::vector<uint8>& data,
  65                                size_t index) const {
  66   DCHECK_LT(index, GetSize(data));
  67   if (index < pending_size_)
  68     return pending_data_[index];
  69   return data[index - pending_size_];
  70 }
  71
  72 bool UsbMidiOutputStream::PushSysExMessage(const std::vector<uint8>& data,
  73                                            size_t* current,
  74                                            std::vector<uint8>* data_to_send) {
  75   size_t index = *current;
  76   size_t message_size = 0;
  77   const size_t kMessageSizeMax = 3;
  78   uint8 message[kMessageSizeMax] = {};
  79
  80   while (index < GetSize(data)) {
  81     if (message_size == kMessageSizeMax) {
  82       // We can't find the end-of-message mark in the three bytes.
  83       *current = index;
  84       data_to_send->push_back((jack_.cable_number << 4) | 0x4);
  85       data_to_send->insert(data_to_send->end(),
  86                            message,
  87                            message + arraysize(message));
  88       is_sending_sysex_ = true;
  89       return true;
  90     }
  91     uint8 byte = Get(data, index);
  92     if ((byte & kSysRTMessageBitMask) == kSysRTMessageBitPattern) {
  93       // System Real-Time messages interleaved in a SysEx message
  94       PushSysRTMessage(data, &index, data_to_send);
  95       continue;
  96     }
  97
  98     message[message_size] = byte;
  99     ++message_size;
 100     if (byte == kEndOfSysExByte) {
 101       uint8 code_index = message_size + 0x4;
 102       DCHECK(code_index == 0x5 || code_index == 0x6 || code_index == 0x7);
 103       data_to_send->push_back((jack_.cable_number << 4) | code_index);
 104       data_to_send->insert(data_to_send->end(),
 105                            message,
 106                            message + arraysize(message));
 107       *current = index + 1;
 108       is_sending_sysex_ = false;
 109       return true;
 110     }
 111     ++index;
 112   }
 113   return false;
 114 }
 115
 116 bool UsbMidiOutputStream::PushSysCommonMessage(
 117     const std::vector<uint8>& data,
 118     size_t* current,
 119     std::vector<uint8>* data_to_send) {
 120   size_t index = *current;
 121   uint8 first_byte = Get(data, index);
 122   DCHECK_LE(0xf1, first_byte);
 123   DCHECK_LE(first_byte, 0xf7);
 124   const size_t message_size_table[8] = {
 125     0, 2, 3, 2, 1, 1, 1, 0,
 126   };
 127   size_t message_size = message_size_table[first_byte & 0x0f];
 128   DCHECK_NE(0u, message_size);
 129   DCHECK_LE(message_size, 3u);
 130
 131   if (GetSize(data) < index + message_size) {
 132     // The message is incomplete.
 133     return false;
 134   }
 135
 136   uint8 code_index = message_size == 1 ? 0x5 : static_cast<uint8>(message_size);
 137   data_to_send->push_back((jack_.cable_number << 4) | code_index);
 138   for (size_t i = index; i < index + 3; ++i)
 139     data_to_send->push_back(i < index + message_size ? Get(data, i) : 0);
 140   *current += message_size;
 141   return true;
 142 }
 143
 144 void UsbMidiOutputStream::PushSysRTMessage(const std::vector<uint8>& data,
 145                                            size_t* current,
 146                                            std::vector<uint8>* data_to_send) {
 147   size_t index = *current;
 148   uint8 first_byte = Get(data, index);
 149   DCHECK_LE(0xf8, first_byte);
 150   DCHECK_LE(first_byte, 0xff);
 151
 152   data_to_send->push_back((jack_.cable_number << 4) | 0x5);
 153   data_to_send->push_back(first_byte);
 154   data_to_send->push_back(0);
 155   data_to_send->push_back(0);
 156   *current += 1;
 157 }
 158
 159 bool UsbMidiOutputStream::PushChannelMessage(const std::vector<uint8>& data,
 160                                            size_t* current,
 161                                            std::vector<uint8>* data_to_send) {
 162   size_t index = *current;
 163   uint8 first_byte = Get(data, index);
 164   DCHECK_LE(0x80, (first_byte & 0xf0));
 165   DCHECK_LE((first_byte & 0xf0), 0xe0);
 166
 167   const size_t message_size_table[8] = {
 168     3, 3, 3, 3, 2, 3, 3, 0,
 169   };
 170   uint8 code_index = first_byte >> 4;
 171   size_t message_size = message_size_table[code_index & 0x7];
 172   DCHECK_NE(0u, message_size);
 173   DCHECK_LE(message_size, 3u);
 174
 175   if (GetSize(data) < index + message_size) {
 176     // The message is incomplete.
 177     return false;
 178   }
 179
 180   data_to_send->push_back((jack_.cable_number << 4) | code_index);
 181   for (size_t i = index; i < index + 3; ++i)
 182     data_to_send->push_back(i < index + message_size ? Get(data, i) : 0);
 183   *current += message_size;
 184   return true;
 185 }
 186
 187 }  // namespace media