Revert 237558 "Use MIDIMessageQueue/IsValidWebMIDIData for MIDI ..."

trunk/src/media/midi/midi_message_queue.cc

-// 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/logging.h"
-#include "media/midi/midi_message_util.h"
-
-namespace media {
-namespace {
-
-const uint8 kSysEx = 0xf0;
-const uint8 kEndOfSysEx = 0xf7;
-
-bool IsDataByte(uint8 data) {
-  return (data & 0x80) == 0;
-}
-
-bool IsFirstStatusByte(uint8 data) {
-  return !IsDataByte(data) && data != kEndOfSysEx;
-}
-
-bool IsSystemRealTimeMessage(uint8 data) {
-  return 0xf8 <= data && data <= 0xff;
-}
-
-}  // namespace
-
-MIDIMessageQueue::MIDIMessageQueue(bool allow_running_status)
-    : allow_running_status_(allow_running_status) {}
-
-MIDIMessageQueue::~MIDIMessageQueue() {}
-
-void MIDIMessageQueue::Add(const std::vector<uint8>& data) {
-  queue_.insert(queue_.end(), data.begin(), data.end());
-}
-
-void MIDIMessageQueue::Add(const uint8* data, size_t length) {
-  queue_.insert(queue_.end(), data, data + length);
-}
-
-void MIDIMessageQueue::Get(std::vector<uint8>* message) {
-  message->clear();
-
-  while (true) {
-    if (queue_.empty())
-      return;
-
-    const uint8 next = queue_.front();
-    queue_.pop_front();
-
-    // "System Real Time Messages" is a special kind of MIDI messages, which can
-    // appear at 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.
-    if (IsSystemRealTimeMessage(next)) {
-      message->push_back(next);
-      return;
-    }
-
-    // Here |next_message_[0]| may contain the previous status byte when
-    // |allow_running_status_| is true. Following condition fixes up
-    // |next_message_| if running status condition is not fulfilled.
-    if (!next_message_.empty() &&
-        ((next_message_[0] == kSysEx && IsFirstStatusByte(next)) ||
-         (next_message_[0] != kSysEx && !IsDataByte(next)))) {
-      // An invalid data sequence is found or running status condition is not
-      // fulfilled.
-      next_message_.clear();
-    }
-
-    if (next_message_.empty()) {
-      if (IsFirstStatusByte(next)) {
-        next_message_.push_back(next);
-      } else {
-        // MIDI protocol doesn't provide any error correction mechanism in
-        // physical layers, and incoming messages can be corrupted, and should
-        // be corrected here.
-      }
-      continue;
-    }
-
-    // Here we can assume |next_message_| starts with a valid status byte.
-    const uint8 status_byte = next_message_[0];
-    next_message_.push_back(next);
-
-    if (status_byte == kSysEx) {
-      if (next == kEndOfSysEx) {
-        std::swap(*message, next_message_);
-        next_message_.clear();
-        return;
-      }
-      continue;
-    }
-
-    DCHECK(IsDataByte(next));
-    DCHECK_NE(kSysEx, status_byte);
-    const size_t target_len = GetMIDIMessageLength(status_byte);
-    if (next_message_.size() < target_len)
-      continue;
-    if (next_message_.size() == target_len) {
-      std::swap(*message, next_message_);
-      next_message_.clear();
-      if (allow_running_status_) {
-        // Speculatively keep the status byte in case of running status. If this
-        // assumption is not true, |next_message_| will be cleared anyway.
-        next_message_.push_back(status_byte);
-      }
-      return;
-    }
-
-    NOTREACHED();
-  }
-}
-
-}  // namespace media