Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 124 insertions, 0 deletions

diff --git a/dom/midi/MIDIUtils.cpp b/dom/midi/MIDIUtils.cpp
new file mode 100644
index 0000000000..6e2a7f75af
--- /dev/null
+++ b/dom/midi/MIDIUtils.cpp
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/MIDITypes.h"
+#include "mozilla/dom/MIDIUtils.h"
+#include "mozilla/UniquePtr.h"
+
+// Taken from MIDI IMPLEMENTATION CHART INSTRUCTIONS, MIDI Spec v1.0, Pg. 97
+static const uint8_t kCommandByte = 0x80;
+static const uint8_t kSysexMessageStart = 0xF0;
+static const uint8_t kSystemMessage = 0xF0;
+static const uint8_t kSysexMessageEnd = 0xF7;
+static const uint8_t kSystemRealtimeMessage = 0xF8;
+// Represents the length of all possible command messages.
+// Taken from MIDI Spec, Pg. 101v 1.0, Table 2
+static const uint8_t kCommandLengths[] = {3, 3, 3, 3, 2, 2, 3};
+// Represents the length of all possible system messages. The length of sysex
+// messages is variable, so we just put zero since it won't be checked anyways.
+// Taken from MIDI Spec v1.0, Pg. 105, Table 5
+static const uint8_t kSystemLengths[] = {0, 2, 3, 2, 1, 1, 1, 1};
+
+namespace mozilla::dom::MIDIUtils {
+
+// Checks validity of MIDIMessage passed to it. Throws debug warnings and
+// returns false if message is not valid.
+bool IsValidMessage(const MIDIMessage* aMsg) {
+  if (NS_WARN_IF(!aMsg)) {
+    return false;
+  }
+  // Assert on parser problems
+  MOZ_ASSERT(aMsg->data().Length() > 0,
+             "Created a MIDI Message of Length 0. This should never happen!");
+  uint8_t cmd = aMsg->data()[0];
+  // If first byte isn't a command, something is definitely wrong.
+  MOZ_ASSERT((cmd & kCommandByte) == kCommandByte,
+             "Constructed a MIDI packet where first byte is not command!");
+  if (cmd == kSysexMessageStart) {
+    // All we can do with sysex is make sure it starts and  ends with the
+    // correct command bytes.
+    if (aMsg->data()[aMsg->data().Length() - 1] != kSysexMessageEnd) {
+      NS_WARNING("Last byte of Sysex Message not 0xF7!");
+      return false;
+    }
+    return true;
+  }
+  // For system realtime messages, the length should always be 1.
+  if ((cmd & kSystemRealtimeMessage) == kSystemRealtimeMessage) {
+    return aMsg->data().Length() == 1;
+  }
+  // Otherwise, just use the correct array for testing lengths. We can't tell
+  // much about message validity other than that.
+  if ((cmd & kSystemMessage) == kSystemMessage) {
+    if (cmd - kSystemMessage >=
+        static_cast<uint8_t>(ArrayLength(kSystemLengths))) {
+      NS_WARNING("System Message Command byte not valid!");
+      return false;
+    }
+    return aMsg->data().Length() == kSystemLengths[cmd - kSystemMessage];
+  }
+  // For non system commands, we only care about differences in the high nibble
+  // of the first byte. Shift this down to give the index of the expected packet
+  // length.
+  uint8_t cmdIndex = (cmd - kCommandByte) >> 4;
+  if (cmdIndex >= ArrayLength(kCommandLengths)) {
+    // If our index is bigger than our array length, command byte is unknown;
+    NS_WARNING("Unknown MIDI command!");
+    return false;
+  }
+  return aMsg->data().Length() == kCommandLengths[cmdIndex];
+}
+
+uint32_t ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
+                       const TimeStamp& aTimestamp,
+                       nsTArray<MIDIMessage>& aMsgArray) {
+  uint32_t bytesRead = 0;
+  bool inSysexMessage = false;
+  UniquePtr<MIDIMessage> currentMsg;
+  for (auto& byte : aByteBuffer) {
+    bytesRead++;
+    if ((byte & kSystemRealtimeMessage) == kSystemRealtimeMessage) {
+      MIDIMessage rt_msg;
+      rt_msg.data().AppendElement(byte);
+      rt_msg.timestamp() = aTimestamp;
+      aMsgArray.AppendElement(rt_msg);
+      continue;
+    }
+    if (byte == kSysexMessageEnd) {
+      if (!inSysexMessage) {
+        MOZ_ASSERT(inSysexMessage);
+        NS_WARNING(
+            "Got sysex message end with no sysex message being processed!");
+      }
+      inSysexMessage = false;
+    } else if (byte & kCommandByte) {
+      if (currentMsg && IsValidMessage(currentMsg.get())) {
+        aMsgArray.AppendElement(*currentMsg);
+      }
+      currentMsg = MakeUnique<MIDIMessage>();
+      currentMsg->timestamp() = aTimestamp;
+    }
+    currentMsg->data().AppendElement(byte);
+    if (byte == kSysexMessageStart) {
+      inSysexMessage = true;
+    }
+  }
+  if (currentMsg && IsValidMessage(currentMsg.get())) {
+    aMsgArray.AppendElement(*currentMsg);
+  }
+  return bytesRead;
+}
+
+bool IsSysexMessage(const MIDIMessage& aMsg) {
+  if (aMsg.data().Length() == 0) {
+    return false;
+  }
+  if (aMsg.data()[0] == kSysexMessageStart) {
+    return true;
+  }
+  return false;
+}
+}  // namespace mozilla::dom::MIDIUtils