/usr/share/libsigrokdecode/decoders/midi/pd.py is in libsigrokdecode4 0.5.0-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2013-2016 Uwe Hermann <uwe@hermann-uwe.de>
## Copyright (C) 2016 Chris Dreher <chrisdreher@hotmail.com>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, see <http://www.gnu.org/licenses/>.
##
import sigrokdecode as srd
from .lists import *
RX = 0
TX = 1
class Decoder(srd.Decoder):
api_version = 2
id = 'midi'
name = 'MIDI'
longname = 'Musical Instrument Digital Interface'
desc = 'Musical Instrument Digital Interface (MIDI) protocol.'
license = 'gplv2+'
inputs = ['uart']
outputs = ['midi']
annotations = (
('text-verbose', 'Human-readable text (verbose)'),
('text-sysreal-verbose', 'Human-readable SysReal text (verbose)'),
('text-error', 'Human-readable Error text'),
)
annotation_rows = (
('normal', 'Normal', (0, 2)),
('sys-real', 'SysReal', (1,)),
)
def __init__(self):
self.state = 'IDLE'
self.status_byte = 0
self.explicit_status_byte = False
self.cmd = []
self.ss = None
self.es = None
self.ss_block = None
self.es_block = None
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
def putx(self, data):
self.put(self.ss_block, self.es_block, self.out_ann, data)
def get_note_name(self, channel, note):
if channel != 10:
return chromatic_notes[note]
else:
return 'assuming ' + percussion_notes.get(note, 'undefined')
def check_for_garbage_flush(self, is_flushed):
if is_flushed:
if self.explicit_status_byte:
self.cmd.insert(0, self.status_byte)
self.handle_garbage_msg(None)
def soft_clear_status_byte(self):
self.explicit_status_byte = False
def hard_clear_status_byte(self):
self.status_byte = 0
self.explicit_status_byte = False
def set_status_byte(self, newbyte):
self.status_byte = newbyte
self.explicit_status_byte = True
def handle_channel_msg_0x80(self, is_flushed):
# Note off: 8n kk vv
# n = channel, kk = note, vv = velocity
c = self.cmd
if len(c) < 2:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
note, velocity = c[0], c[1]
note_name = self.get_note_name(chan, note)
self.putx([0, ['Channel %d: %s (note = %d \'%s\', velocity = %d)' % \
(chan, status_bytes[msg][0], note, note_name, velocity),
'ch %d: %s %d, velocity = %d' % \
(chan, status_bytes[msg][1], note, velocity),
'%d: %s %d, vel %d' % \
(chan, status_bytes[msg][2], note, velocity)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0x90(self, is_flushed):
# Note on: 9n kk vv
# n = channel, kk = note, vv = velocity
# If velocity == 0 that actually means 'note off', though.
c = self.cmd
if len(c) < 2:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
note, velocity = c[0], c[1]
s = status_bytes[0x80] if (velocity == 0) else status_bytes[msg]
note_name = self.get_note_name(chan, note)
self.putx([0, ['Channel %d: %s (note = %d \'%s\', velocity = %d)' % \
(chan, s[0], note, note_name, velocity),
'ch %d: %s %d, velocity = %d' % \
(chan, s[1], note, velocity),
'%d: %s %d, vel %d' % \
(chan, s[2], note, velocity)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0xa0(self, is_flushed):
# Polyphonic key pressure / aftertouch: An kk vv
# n = channel, kk = polyphonic key pressure, vv = pressure value
c = self.cmd
if len(c) < 2:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
note, pressure = c[0], c[1]
note_name = self.get_note_name(chan, note)
self.putx([0, ['Channel %d: %s of %d for note = %d \'%s\'' % \
(chan, status_bytes[msg][0], pressure, note, note_name),
'ch %d: %s %d for note %d' % \
(chan, status_bytes[msg][1], pressure, note),
'%d: %s %d, N %d' % \
(chan, status_bytes[msg][2], pressure, note)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_controller_0x44(self):
# Legato footswitch: Bn 44 vv
# n = channel, vv = value (<= 0x3f: normal, > 0x3f: legato)
c = self.cmd
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
vv = c[1]
t = ('normal', 'no') if vv <= 0x3f else ('legato', 'yes')
self.putx([0, ['Channel %d: %s \'%s\' = %s' % \
(chan, status_bytes[msg][0],
control_functions[0x44][0], t[0]),
'ch %d: %s \'%s\' = %s' % \
(chan, status_bytes[msg][1],
control_functions[0x44][1], t[0]),
'%d: %s \'%s\' = %s' % \
(chan, status_bytes[msg][2],
control_functions[0x44][2], t[1])]])
def handle_controller_0x54(self):
# Portamento control (PTC): Bn 54 kk
# n = channel, kk = source note for pitch reference
c = self.cmd
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
kk = c[1]
kk_name = self.get_note_name(chan, kk)
self.putx([0, ['Channel %d: %s \'%s\' (source note = %d / %s)' % \
(chan, status_bytes[msg][0],
control_functions[0x54][0], kk, kk_name),
'ch %d: %s \'%s\' (source note = %d)' % \
(chan, status_bytes[msg][1],
control_functions[0x54][1], kk),
'%d: %s \'%s\' (src N %d)' % \
(chan, status_bytes[msg][2],
control_functions[0x54][2], kk)]])
def handle_controller_generic(self):
c = self.cmd
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
fn, param = c[0], c[1]
default_name = 'undefined'
ctrl_fn = control_functions.get(fn, default_name)
if ctrl_fn == default_name:
ctrl_fn = ('undefined 0x%02x' % fn, 'undef 0x%02x' % fn, '0x%02x' % fn)
self.putx([0, ['Channel %d: %s \'%s\' (param = 0x%02x)' % \
(chan, status_bytes[msg][0], ctrl_fn[0], param),
'ch %d: %s \'%s\' (param = 0x%02x)' % \
(chan, status_bytes[msg][1], ctrl_fn[1], param),
'%d: %s \'%s\' is 0x%02x' % \
(chan, status_bytes[msg][2], ctrl_fn[2], param)]])
def handle_channel_mode(self):
# Channel Mode: Bn mm vv
# n = channel, mm = mode number (120 - 127), vv = value
c = self.cmd
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
mm, vv = c[0], c[1]
mode_fn = control_functions.get(mm, ('undefined', 'undef', 'undef'))
# Decode the value based on the mode number.
vv_string = ('', '')
if mm == 122: # mode = local control?
if vv == 0:
vv_string = ('off', 'off')
elif vv == 127: # mode = poly mode on?
vv_string = ('on', 'on')
else:
vv_string = ('(non-standard param value of 0x%02x)' % vv,
'0x%02x' % vv)
elif mm == 126: # mode = mono mode on?
if vv != 0:
vv_string = ('(%d channels)' % vv, '(%d ch)' % vv)
else:
vv_string = ('(channels \'basic\' through 16)',
'(ch \'basic\' thru 16)')
elif vv != 0: # All other channel mode messages expect vv == 0.
vv_string = ('(non-standard param value of 0x%02x)' % vv,
'0x%02x' % vv)
self.putx([0, ['Channel %d: %s \'%s\' %s' % \
(chan, status_bytes[msg][0], mode_fn[0], vv_string[0]),
'ch %d: %s \'%s\' %s' % \
(chan, status_bytes[msg][1], mode_fn[1], vv_string[1]),
'%d: %s \'%s\' %s' % \
(chan, status_bytes[msg][2], mode_fn[2], vv_string[1])]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0xb0(self, is_flushed):
# Control change (or channel mode messages): Bn cc vv
# n = channel, cc = control number (0 - 119), vv = control value
c = self.cmd
if len(c) < 2:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
if c[0] in range(0x78, 0x7f + 1):
self.handle_channel_mode()
return
handle_ctrl = getattr(self, 'handle_controller_0x%02x' % c[0],
self.handle_controller_generic)
handle_ctrl()
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0xc0(self, is_flushed):
# Program change: Cn pp
# n = channel, pp = program number (0 - 127)
c = self.cmd
if len(c) < 1:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
pp = self.cmd[0] + 1
change_type = 'instrument'
name = ''
if chan != 10: # channel != percussion
name = gm_instruments.get(pp, 'undefined')
else:
change_type = 'drum kit'
name = drum_kit.get(pp, 'undefined')
self.putx([0, ['Channel %d: %s to %s %d (assuming %s)' % \
(chan, status_bytes[msg][0], change_type, pp, name),
'ch %d: %s to %s %d' % \
(chan, status_bytes[msg][1], change_type, pp),
'%d: %s %d' % \
(chan, status_bytes[msg][2], pp)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0xd0(self, is_flushed):
# Channel pressure / aftertouch: Dn vv
# n = channel, vv = pressure value
c = self.cmd
if len(c) < 1:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
vv = self.cmd[0]
self.putx([0, ['Channel %d: %s %d' % (chan, status_bytes[msg][0], vv),
'ch %d: %s %d' % (chan, status_bytes[msg][1], vv),
'%d: %s %d' % (chan, status_bytes[msg][2], vv)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_0xe0(self, is_flushed):
# Pitch bend change: En ll mm
# n = channel, ll = pitch bend change LSB, mm = pitch bend change MSB
c = self.cmd
if len(c) < 2:
self.check_for_garbage_flush(is_flushed)
return
self.es_block = self.es
msg, chan = self.status_byte & 0xf0, (self.status_byte & 0x0f) + 1
ll, mm = self.cmd[0], self.cmd[1]
decimal = (mm << 7) + ll
self.putx([0, ['Channel %d: %s 0x%02x 0x%02x (%d)' % \
(chan, status_bytes[msg][0], ll, mm, decimal),
'ch %d: %s 0x%02x 0x%02x (%d)' % \
(chan, status_bytes[msg][1], ll, mm, decimal),
'%d: %s (%d)' % \
(chan, status_bytes[msg][2], decimal)]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg_generic(self, is_flushed):
# TODO: It should not be possible to hit this code.
# It currently can not be unit tested.
msg_type = self.status_byte & 0xf0
self.es_block = self.es
self.putx([2, ['Unknown channel message type: 0x%02x' % msg_type]])
self.cmd, self.state = [], 'IDLE'
self.soft_clear_status_byte()
def handle_channel_msg(self, newbyte):
if newbyte is not None:
if newbyte >= 0x80:
self.set_status_byte(newbyte)
else:
self.cmd.append(newbyte)
msg_type = self.status_byte & 0xf0
handle_msg = getattr(self, 'handle_channel_msg_0x%02x' % msg_type,
self.handle_channel_msg_generic)
handle_msg(newbyte is None)
def handle_sysex_msg(self, newbyte):
# SysEx message: 1 status byte, 1-3 manuf. bytes, x data bytes, EOX byte
#
# SysEx messages are variable length, can be terminated by EOX or
# by any non-SysReal status byte, and it clears self.status_byte.
#
# Note: All System message codes don't utilize self.status_byte.
self.hard_clear_status_byte()
if newbyte != 0xf7 and newbyte is not None: # EOX
self.cmd.append(newbyte)
return
self.es_block = self.es
# Note: Unlike other methods, this code pops bytes out of self.cmd
# to isolate the data.
msg = self.cmd.pop(0)
if len(self.cmd) < 1:
self.putx([2, ['%s: truncated manufacturer code (<1 bytes)' % \
status_bytes[msg][0],
'%s: truncated manufacturer (<1 bytes)' % \
status_bytes[msg][1],
'%s: trunc. manu.' % status_bytes[msg][2]]])
self.cmd, self.state = [], 'IDLE'
return
# Extract the manufacturer name (or SysEx realtime or non-realtime).
m1 = self.cmd.pop(0)
manu = (m1,)
if m1 == 0x00: # If byte == 0, then 2 more manufacturer bytes follow.
if len(self.cmd) < 2:
self.putx([2, ['%s: truncated manufacturer code (<3 bytes)' % \
status_bytes[msg][0],
'%s: truncated manufacturer (<3 bytes)' % \
status_bytes[msg][1],
'%s: trunc. manu.' % status_bytes[msg][2]]])
self.cmd, self.state = [], 'IDLE'
return
manu = (m1, self.cmd.pop(0), self.cmd.pop(0))
default_name = 'undefined'
manu_name = sysex_manufacturer_ids.get(manu, default_name)
if manu_name == default_name:
if len(manu) == 3:
manu_name = ('%s (0x%02x 0x%02x 0x%02x)' % \
(default_name, manu[0], manu[1], manu[2]),
default_name)
else:
manu_name = ('%s (0x%02x)' % (default_name, manu[0]),
default_name)
else:
manu_name = (manu_name, manu_name)
# Extract the payload, display in 1 of 2 formats
# TODO: Write methods to decode SysEx realtime & non-realtime payloads.
payload0 = ''
payload1 = ''
while len(self.cmd) > 0:
byte = self.cmd.pop(0)
payload0 += '0x%02x ' % (byte)
payload1 += '%02x ' % (byte)
if payload0 == '':
payload0 = '<empty>'
payload1 = '<>'
payload = (payload0, payload1)
self.putx([0, ['%s: for \'%s\' with payload %s' % \
(status_bytes[msg][0], manu_name[0], payload[0]),
'%s: \'%s\', payload %s' % \
(status_bytes[msg][1], manu_name[1], payload[1]),
'%s: \'%s\', payload %s' % \
(status_bytes[msg][2], manu_name[1], payload[1])]])
self.cmd, self.state = [], 'IDLE'
def handle_syscommon_midi_time_code_quarter_frame_msg(self, newbyte):
# MIDI time code quarter frame: F1 nd
# n = message type
# d = values
#
# Note: All System message codes don't utilize self.status_byte,
# and System Exclusive and System Common clear it.
c = self.cmd
if len(c) < 2:
if newbyte is None:
self.handle_garbage_msg(None)
return
msg = c[0]
nn, dd = (c[1] & 0x70) >> 4, c[1] & 0x0f
group = ('System Common', 'SysCom', 'SC')
self.es_block = self.es
if nn != 7: # If message type does not contain SMPTE type.
self.putx([0, ['%s: %s of %s, value 0x%01x' % \
(group[0], status_bytes[msg][0],
quarter_frame_type[nn][0], dd),
'%s: %s of %s, value 0x%01x' % \
(group[1], status_bytes[msg][1],
quarter_frame_type[nn][1], dd),
'%s: %s of %s, value 0x%01x' % \
(group[2], status_bytes[msg][2],
quarter_frame_type[nn][1], dd)]])
self.cmd, self.state = [], 'IDLE'
return
tt = (dd & 0x6) >> 1
self.putx([0, ['%s: %s of %s, value 0x%01x for %s' % \
(group[0], status_bytes[msg][0], \
quarter_frame_type[nn][0], dd, smpte_type[tt]),
'%s: %s of %s, value 0x%01x for %s' % \
(group[1], status_bytes[msg][1], \
quarter_frame_type[nn][1], dd, smpte_type[tt]),
'%s: %s of %s, value 0x%01x for %s' % \
(group[2], status_bytes[msg][2], \
quarter_frame_type[nn][1], dd, smpte_type[tt])]])
self.cmd, self.state = [], 'IDLE'
def handle_syscommon_msg(self, newbyte):
# System common messages
#
# There are 5 simple formats (which are directly handled here) and
# 1 complex one called MIDI time code quarter frame.
#
# Note: While the MIDI lists 0xf7 as a "system common" message, it
# is actually only used with SysEx messages so it is processed there.
#
# Note: All System message codes don't utilize self.status_byte.
self.hard_clear_status_byte()
if newbyte is not None:
self.cmd.append(newbyte)
c = self.cmd
msg = c[0]
group = ('System Common', 'SysCom', 'SC')
if msg == 0xf1:
# MIDI time code quarter frame
self.handle_syscommon_midi_time_code_quarter_frame_msg(newbyte)
return
elif msg == 0xf2:
# Song position pointer: F2 ll mm
# ll = LSB position, mm = MSB position
if len(c) < 3:
if newbyte is None:
self.handle_garbage_msg(None)
return
ll, mm = c[1], c[2]
decimal = (mm << 7) + ll
self.es_block = self.es
self.putx([0, ['%s: %s 0x%02x 0x%02x (%d)' % \
(group[0], status_bytes[msg][0], ll, mm, decimal),
'%s: %s 0x%02x 0x%02x (%d)' % \
(group[1], status_bytes[msg][1], ll, mm, decimal),
'%s: %s (%d)' % \
(group[2], status_bytes[msg][2], decimal)]])
elif msg == 0xf3:
# Song select: F3 ss
# ss = song selection number
if len(c) < 2:
if newbyte is None:
self.handle_garbage_msg(None)
return
ss = c[1]
self.es_block = self.es
self.putx([0, ['%s: %s number %d' % \
(group[0], status_bytes[msg][0], ss),
'%s: %s number %d' % \
(group[1], status_bytes[msg][1], ss),
'%s: %s # %d' % \
(group[2], status_bytes[msg][2], ss)]])
elif msg == 0xf4 or msg == 0xf5 or msg == 0xf6:
# Undefined 0xf4, Undefined 0xf5, and Tune Request (respectively).
# All are only 1 byte long with no data bytes.
self.es_block = self.es
self.putx([0, ['%s: %s' % (group[0], status_bytes[msg][0]),
'%s: %s' % (group[1], status_bytes[msg][1]),
'%s: %s' % (group[2], status_bytes[msg][2])]])
self.cmd, self.state = [], 'IDLE'
def handle_sysrealtime_msg(self, newbyte):
# System realtime message: 0b11111ttt (t = message type)
#
# Important: These messages are handled differently from all others
# because they are allowed to temporarily interrupt other messages.
# The interrupted messages resume after the realtime message is done.
# Thus, they mostly leave 'self' the way it was found.
#
# Note: All System message codes don't utilize self.status_byte.
old_ss_block, old_es_block = self.ss_block, self.es_block
self.ss_block, self.es_block = self.ss, self.es
group = ('System Realtime', 'SysReal', 'SR')
self.putx([1, ['%s: %s' % (group[0], status_bytes[newbyte][0]),
'%s: %s' % (group[1], status_bytes[newbyte][1]),
'%s: %s' % (group[2], status_bytes[newbyte][2])]])
self.ss_block, self.es_block = old_ss_block, old_es_block
# Deliberately not resetting self.cmd or self.state.
def handle_garbage_msg(self, newbyte):
# Handle messages that are either not handled or are corrupt.
self.es_block = self.es
if newbyte is not None:
self.cmd.append(newbyte)
return
payload = '<empty>'
max_bytes = 16 # Put a limit on the length on the hex dump.
for index in range(len(self.cmd)):
if index == max_bytes:
payload += ' ...'
break
if index == 0:
payload = '0x%02x' % self.cmd[index]
else:
payload += ' 0x%02x' % self.cmd[index]
self.putx([2, ['UNHANDLED DATA: %s' % payload,
'UNHANDLED', '???', '?']])
self.cmd, self.state = [], 'IDLE'
self.hard_clear_status_byte()
def handle_state(self, state, newbyte):
# 'newbyte' can either be:
# 1. Value between 0x00-0xff, deal with the byte normally.
# 2. Value of 'None' which means "flush any buffered data".
if state == 'HANDLE CHANNEL MSG':
self.handle_channel_msg(newbyte)
elif state == 'HANDLE SYSEX MSG':
self.handle_sysex_msg(newbyte)
elif state == 'HANDLE SYSCOMMON MSG':
self.handle_syscommon_msg(newbyte)
elif state == 'HANDLE SYSREALTIME MSG':
self.handle_sysrealtime_msg(newbyte)
elif state == 'BUFFER GARBAGE MSG':
self.handle_garbage_msg(newbyte)
def get_next_state(self, newbyte):
# 'newbyte' must be a valid byte between 0x00 and 0xff.
#
# Try to determine the state based off of the 'newbyte' parameter.
if newbyte in range(0x80, 0xef + 1):
return 'HANDLE CHANNEL MSG'
if newbyte == 0xf0:
return 'HANDLE SYSEX MSG'
if newbyte in range(0xf1, 0xf7):
return'HANDLE SYSCOMMON MSG'
if newbyte in range(0xf8, 0xff + 1):
return 'HANDLE SYSREALTIME MSG'
# Passing 0xf7 is an error; messages don't start with 0xf7.
if newbyte == 0xf7:
return 'BUFFER GARBAGE MSG'
# Next, base the state off of self.status_byte.
if self.status_byte < 0x80:
return 'BUFFER GARBAGE MSG'
return self.get_next_state(self.status_byte)
def decode(self, ss, es, data):
ptype, rxtx, pdata = data
state = 'IDLE'
# For now, ignore all UART packets except the actual data packets.
if ptype != 'DATA':
return
# We're only interested in the byte value (not individual bits).
pdata = pdata[0]
# Short MIDI overview:
# - Status bytes are 0x80-0xff, data bytes are 0x00-0x7f.
# - Most messages: 1 status byte, 1-2 data bytes.
# - Real-time system messages: always 1 byte.
# - SysEx messages: 1 status byte, n data bytes, EOX byte.
#
# Aspects of the MIDI protocol that complicate decoding:
# - MIDI System Realtime messages can briefly interrupt other
# messages already in progress.
# - "Running Status" allows for omitting the status byte in most
# scenarios if sequential messages have the same status byte.
# - System Exclusive (SysEx) messages can be terminated by ANY
# status byte (not limited to EOX byte).
# State machine.
if pdata >= 0x80 and pdata != 0xf7:
state = self.get_next_state(pdata)
if state != 'HANDLE SYSREALTIME MSG' and self.state != 'IDLE':
# Flush the previous data since a new message is starting.
self.handle_state(self.state, None)
# Cache ss and es -after- flushing previous data.
self.ss, self.es = ss, es
# This is a status byte, remember the start sample.
if state != 'HANDLE SYSREALTIME MSG':
self.ss_block = ss
elif self.state == 'IDLE' or self.state == 'BUFFER GARBAGE MSG':
# Deal with "running status" or that we're buffering garbage.
self.ss, self.es = ss, es
if self.state == 'IDLE':
self.ss_block = ss
state = self.get_next_state(pdata)
else:
self.ss, self.es = ss, es
state = self.state
# Yes, this is intentionally _not_ an 'elif' here.
if state != 'HANDLE SYSREALTIME MSG':
self.state = state
if state == 'BUFFER GARBAGE MSG':
self.status_byte = 0
self.handle_state(state, pdata)
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