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# SPDX-FileCopyrightText: 2016 Ole Martin Bjorndalen <ombdalen@gmail.com>
#
# SPDX-License-Identifier: MIT
"""Mido amidi backend
Very experimental backend using amidi to access the ALSA rawmidi
interface.
TODO:
* use parser instead of from_hex()?
* default port name
* do sysex messages work?
* starting amidi for every message sent is costly
"""
import select
import subprocess
import threading
from ..messages import Message
from ._common import InputMethods, OutputMethods, PortMethods
"""
Dir Device Name
IO hw:1,0,0 UM-1 MIDI 1
IO hw:2,0,0 nanoKONTROL2 MIDI 1
IO hw:2,0,0 MPK mini MIDI 1
"""
def get_devices():
devices = []
lines = subprocess.check_output(
["amidi", "-l"],
encoding="utf-8",
).splitlines()
for line in lines[1:]:
mode, device, name = line.strip().split(None, 2)
devices.append({'name': name.strip(),
'device': device,
'is_input': 'I' in mode,
'is_output': 'O' in mode,
})
return devices
def _get_device(name, mode):
for dev in get_devices():
if name == dev['name'] and dev[mode]:
return dev
else:
raise OSError(f'unknown port {name!r}')
class Input(PortMethods, InputMethods):
def __init__(self, name=None, **kwargs):
self.name = name
self.closed = False
self._proc = None
self._poller = select.poll()
self._lock = threading.RLock()
dev = _get_device(self.name, 'is_input')
self._proc = subprocess.Popen(['amidi', '-d',
'-p', dev['device']],
stdout=subprocess.PIPE)
self._poller.register(self._proc.stdout, select.POLLIN)
def _read_message(self):
line = self._proc.stdout.readline().strip().decode('ascii')
if line:
return Message.from_hex(line)
else:
# The first line is sometimes blank.
return None
def receive(self, block=True):
if not block:
return self.poll()
while True:
msg = self.poll()
if msg:
return msg
# Wait for message.
self._poller.poll()
def poll(self):
with self._lock:
while self._poller.poll(0):
msg = self._read_message()
if msg is not None:
return msg
def close(self):
if not self.closed:
if self._proc:
self._proc.kill()
self._proc = None
self.closed = True
class Output(PortMethods, OutputMethods):
def __init__(self, name=None, autoreset=False, **kwargs):
self.name = name
self.autoreset = autoreset
self.closed = False
self._dev = _get_device(self.name, 'is_output')
def send(self, msg):
proc = subprocess.Popen(['amidi', '--send-hex', msg.hex(),
'-p', self._dev['device']])
proc.wait()
def close(self):
if not self.closed:
if self.autoreset:
self.reset()
self.closed = True
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