Add initial MIDI protocol decoder.

This supports a certain number of MIDI messages already, but not yet all
of them. More will be added later.

1 files changed, 221 insertions, 0 deletions

diff --git a/decoders/midi/pd.py b/decoders/midi/pd.py
new file mode 100644
index 0000000..f718632
--- /dev/null
+++ b/decoders/midi/pd.py
@@ -0,0 +1,221 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2013 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## 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, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+# MIDI protocol decoder
+
+import sigrokdecode as srd
+from .lists import *
+
+RX = 0
+TX = 1
+
+class Decoder(srd.Decoder):
+    api_version = 1
+    id = 'midi'
+    name = 'MIDI'
+    longname = 'Musical Instrument Digital Interface'
+    desc = 'Musical Instrument Digital Interface (MIDI) protocol.'
+    license = 'gplv2+'
+    inputs = ['uart']
+    outputs = ['midi']
+    probes = []
+    optional_probes = []
+    options = {}
+    annotations = [
+        ['Text (verbose)', 'Human-readable text (verbose)'],
+        # ['Text', 'Human-readable text'],
+    ]
+
+    def __init__(self, **kwargs):
+        self.cmd = []
+        self.state = 'IDLE'
+        self.ss = None
+        self.es = None
+        self.ss_block = None
+        self.es_block = None
+
+    def start(self, metadata):
+        # self.out_proto = self.add(srd.OUTPUT_PROTO, 'midi')
+        self.out_ann = self.add(srd.OUTPUT_ANN, 'midi')
+
+    def report(self):
+        pass
+
+    def putx(self, data):
+        self.put(self.ss_block, self.es_block, self.out_ann, data)
+
+    def handle_channel_msg_0x80(self):
+        # Note off: 8n kk vv
+        # n = channel, kk = note, vv = velocity
+        c = self.cmd
+        if len(c) < 3:
+            return
+        self.es_block = self.es
+        msg, chan, note, velocity = c[0] & 0xf0, (c[0] & 0x0f) + 1, c[1], c[2]
+        self.putx([0, ['Channel %d: %s (note = %d, velocity = %d)' % \
+                  (chan, status_bytes[msg], note, velocity)]])
+        self.cmd, self.state = [], 'IDLE'
+
+    def handle_channel_msg_0x90(self):
+        # 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) < 3:
+            return
+        self.es_block = self.ss
+        msg, chan, note, velocity = c[0] & 0xf0, (c[0] & 0x0f) + 1, c[1], c[2]
+        s = 'note off' if (velocity == 0) else status_bytes[msg]
+        self.putx([0, ['Channel %d: %s (note = %d, velocity = %d)' % \
+                  (chan, s, note, velocity)]])
+        self.cmd, self.state = [], 'IDLE'
+
+    def handle_channel_msg_0xa0(self):
+        # Polyphonic key pressure / aftertouch: An kk vv
+        # n = channel, kk = polyphonic key pressure, vv = pressure value
+        pass # TODO
+
+    def handle_controller_0x44(self):
+        # Legato footswitch: Bn 44 vv
+        # n = channel, vv = value (<= 0x3f: normal, > 0x3f: legato)
+        chan, vv = (self.cmd[0] & 0x0f) + 1, self.cmd[2]
+        t = 'normal' if vv <= 0x3f else 'legato'
+        self.putx([0, ['Channel %d: control function \'%s\' = %s' % \
+                  (chan, control_functions[0x44], t)]])
+
+    def handle_controller_0x54(self):
+        # Portamento control (PTC): Bn 54 kk
+        # n = channel, kk = source note for pitch reference
+        chan, kk = (self.cmd[0] & 0x0f) + 1, self.cmd[2]
+        self.putx([0, ['Channel %d: control function \'%s\' (source note ' \
+                  '= %d)' % (chan, control_functions[0x54], kk)]])
+
+    def handle_controller_generic(self):
+        c = self.cmd
+        chan, fn, param = (c[0] & 0x0f) + 1, c[1], c[2]
+        ctrl_fn = control_functions.get(fn, 'undefined')
+        self.putx([0, ['Channel %d: control change to function \'%s\' ' \
+                  '(param = 0x%02x)' % (chan, ctrl_fn, param)]])
+
+    def handle_channel_msg_0xb0(self):
+        # 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) and (c[1] in range(0x78, 0x7f + 1)):
+            # This is not a control change, but rather a channel mode message.
+            # TODO: Handle channel mode messages.
+            return
+        if len(c) < 3:
+            return
+        self.es_block = self.es
+        handle_ctrl = getattr(self, 'handle_controller_0x%02x' % c[1],
+                              self.handle_controller_generic)
+        handle_ctrl()
+        self.cmd, self.state = [], 'IDLE'
+
+    def handle_channel_msg_0xc0(self):
+        # Program change: Cn pp
+        # n = channel, pp = program number (0 - 127)
+        pass # TODO
+
+    def handle_channel_msg_0xd0(self):
+        # Channel pressure / aftertouch: Dn vv
+        # n = channel, vv = pressure value
+        pass # TODO
+
+    def handle_channel_msg_0xe0(self):
+        # Pitch bend change: En ll mm
+        # n = channel, ll = pitch bend change LSB, mm = pitch bend change MSB
+        pass # TODO
+
+    def handle_channel_msg_generic(self):
+        msg_type = self.cmd[0] & 0xf0
+        self.putx([0, ['Unknown channel message type: 0x%02x' % msg_type]])
+        # TODO: Handle properly.
+
+    def handle_channel_msg(self, newbyte):
+        self.cmd.append(newbyte)
+        msg_type = self.cmd[0] & 0xf0
+        handle_msg = getattr(self, 'handle_channel_msg_0x%02x' % msg_type,
+                             self.handle_channel_msg_generic)
+        handle_msg()
+
+    def handle_sysex_msg(self, newbyte):
+        # SysEx message: 1 status byte, x data bytes, EOX byte
+        self.cmd.append(newbyte)
+        if newbyte != 0xf7: # EOX
+            return
+        self.es_block = self.es
+        # TODO: Get message ID, vendor ID, message contents, etc.
+        self.putx([0, ['SysEx message']])
+        self.cmd, self.state = [], 'IDLE'
+
+    def handle_syscommon_msg(self, newbyte):
+        pass # TODO
+
+    def handle_sysrealtime_msg(self, newbyte):
+        # System realtime message: 0b11111ttt (t = message type)
+        self.es_block = self.ss
+        self.putx([0, ['System realtime message: %s' % status_bytes[newbyte]]])
+        self.cmd, self.state = [], 'IDLE'
+
+    def decode(self, ss, es, data):
+        ptype, rxtx, pdata = data
+
+        # For now, ignore all UART packets except the actual data packets.
+        if ptype != 'DATA':
+            return
+
+        self.ss, self.es = ss, es
+
+        # 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.
+
+        # State machine.
+        if self.state == 'IDLE':
+            # Wait until we see a status byte (bit 7 must be set).
+            if pdata < 0x80:
+                return # TODO: How to handle? Ignore?
+            # This is a status byte, remember the start sample.
+            self.ss_block = ss
+            if pdata in range(0x80, 0xef + 1):
+                self.state = 'HANDLE CHANNEL MSG'
+            elif pdata == 0xf0:
+                self.state = 'HANDLE SYSEX MSG'
+            elif pdata in range(0xf1, 0xf7 + 1):
+                self.state = 'HANDLE SYSCOMMON MSG'
+            elif pdata in range(0xf8, 0xff + 1):
+                self.state = 'HANDLE SYSREALTIME MSG'
+
+        # Yes, this is intentionally _not_ an 'elif' here.
+        if self.state == 'HANDLE CHANNEL MSG':
+            self.handle_channel_msg(pdata)
+        elif self.state == 'HANDLE SYSEX MSG':
+            self.handle_sysex_msg(pdata)
+        elif self.state == 'HANDLE SYSCOMMON MSG':
+            self.handle_syscommon_msg(pdata)
+        elif self.state == 'HANDLE SYSREALTIME MSG':
+            self.handle_sysrealtime_msg(pdata)
+        else:
+            raise Exception('Invalid state: %s' % self.state)
+