123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109 |
- // Copyright 2013 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "media/midi/midi_message_queue.h"
- #include <algorithm>
- #include "base/check_op.h"
- #include "base/notreached.h"
- #include "media/midi/message_util.h"
- namespace midi {
- MidiMessageQueue::MidiMessageQueue(bool allow_running_status)
- : allow_running_status_(allow_running_status) {}
- MidiMessageQueue::~MidiMessageQueue() = default;
- void MidiMessageQueue::Add(const std::vector<uint8_t>& data) {
- queue_.insert(queue_.end(), data.begin(), data.end());
- }
- void MidiMessageQueue::Add(const uint8_t* data, size_t length) {
- queue_.insert(queue_.end(), data, data + length);
- }
- void MidiMessageQueue::Get(std::vector<uint8_t>* message) {
- message->clear();
- while (true) {
- // Check if |next_message_| is already a complete MIDI message or not.
- if (!next_message_.empty()) {
- const uint8_t status_byte = next_message_.front();
- const size_t target_len = GetMessageLength(status_byte);
- if (target_len == 0) {
- DCHECK_EQ(kSysExByte, status_byte);
- if (next_message_.back() == kEndOfSysExByte) {
- // OK, this is a complete SysEx message.
- std::swap(*message, next_message_);
- DCHECK(next_message_.empty());
- return;
- }
- } else if (next_message_.size() == target_len) {
- // OK, this is a complete non-SysEx message.
- std::swap(*message, next_message_);
- DCHECK(next_message_.empty());
- if (allow_running_status_ && !IsSystemMessage(status_byte)) {
- // Speculatively keep the status byte in case of running status.
- // If this assumption is not true, |next_message_| will be cleared
- // anyway. Note that system common messages should reset the
- // running status.
- next_message_.push_back(status_byte);
- }
- return;
- } else if (next_message_.size() > target_len) {
- NOTREACHED();
- }
- }
- if (queue_.empty())
- return;
- // "System Real Time Messages" is a special MIDI message, which can appear
- // at an arbitrary byte position of MIDI stream. Here we reorder
- // "System Real Time Messages" prior to |next_message_| so that each message
- // can be clearly separated as a complete MIDI message.
- const uint8_t next = queue_.front();
- if (IsSystemRealTimeMessage(next)) {
- message->push_back(next);
- queue_.pop_front();
- return;
- }
- if (next_message_.empty()) {
- const size_t target_len = GetMessageLength(next);
- // If |target_len| is zero, it means either |next| is not a valid status
- // byte or |next| is a valid status byte but the message length is
- // unpredictable. For the latter case, only SysEx can be accepted.
- if (target_len > 0 || next == kSysExByte) {
- next_message_.push_back(next);
- }
- // Consume |next| always, since if |next| isn't status byte, which means
- // that |next| is just corrupted data, or a data byte followed by
- // reserved message, which we are unable to understand and deal with
- // anyway.
- queue_.pop_front();
- continue;
- }
- const uint8_t status_byte = next_message_.front();
- // If we receive a new non-data byte before completing the pending message,
- // drop the pending message and respin the loop to re-evaluate |next|.
- // This also clears the running status byte speculatively added above, as
- // well as any broken incomplete messages.
- if (!IsDataByte(next) &&
- !(status_byte == kSysExByte && next == kEndOfSysExByte)) {
- next_message_.clear();
- continue;
- }
- // OK to consume this byte.
- next_message_.push_back(next);
- queue_.pop_front();
- }
- }
- } // namespace midi
|