Add MIDI Time Code Quarter Frame message support

Author: rdoursenaud

adafruit_midi/mtc_quarter_frame.py

@@ -0,0 +1,69 @@
+# SPDX-FileCopyrightText: 2021 Raphaël Doursenaud
+#
+# SPDX-License-Identifier: MIT
+
+"""
+`adafruit_midi.mtc_quarter_frame`
+================================================================================
+
+MIDI Time Code (MTC) Quarter Frame message.
+
+
+* Author(s): Raphaël Doursenaud
+
+Implementation Notes
+--------------------
+
+Based upon the official MMA0001 / RP004 / RP008 v4.2.1 MIDI Time Code Specification
+
+"""
+
+from adafruit_midi.midi_message import MIDIMessage
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MIDI.git"
+
+
+class MtcQuarterFrame(MIDIMessage):
+    """MIDI Time Code (MTC) Quarter Frame message.
+
+    :param msgtype: The quarter frame message type:
+        - 0: Frame count LS nibble
+        - 1: Frame count MS nibble
+        - 2: Seconds count LS nibble
+        - 3: Seconds count MS nibble
+        - 4: Minutes count LS nibble
+        - 5: Minutes count MS nibble
+        - 6: Hours count LS nibble
+        - 7: Hours count MS nibble and SMPTE Type
+    :param value: The quarter frame value for the specified type.
+    """
+
+    _STATUS = 0xF1
+    _STATUSMASK = 0xFF
+    LENGTH = 2
+
+    def __init__(self, msgtype, value):
+        self.type = msgtype
+        self.value = value
+        super().__init__()
+        if not 0 <= self.type <= 7 or not 0 <= self.value <= 0x0F:
+            raise self._EX_VALUEERROR_OOR
+
+    def __bytes__(self):
+        return bytes(
+            [
+                self._STATUS,
+                (self.type << 4) + self.value  # Assemble low and high nibbles
+            ]
+        )
+
+    @classmethod
+    def from_bytes(cls, msg_bytes):
+        return cls(
+            msg_bytes[1] >> 4,  # High nibble
+            msg_bytes[1] & 15  # Low nibble
+        )
+
+
+MtcQuarterFrame.register_message_type()