From 81a426949dce2b149f17f59a25dd0e6eb781273b Mon Sep 17 00:00:00 2001
From: Abdelhak Bougouffa <abougouffa@fedoraproject.org>
Date: Tue, 2 Feb 2021 10:27:14 +0100
Subject: [PATCH] Add 'PJON' decoder from libsigrokdecode codebase

---
 libsigrokdecode4DSL/decoders/pjon/__init__.py |  25 +
 libsigrokdecode4DSL/decoders/pjon/pd.py       | 603 ++++++++++++++++++
 2 files changed, 628 insertions(+)
 create mode 100644 libsigrokdecode4DSL/decoders/pjon/__init__.py
 create mode 100644 libsigrokdecode4DSL/decoders/pjon/pd.py

diff --git a/libsigrokdecode4DSL/decoders/pjon/__init__.py b/libsigrokdecode4DSL/decoders/pjon/__init__.py
new file mode 100644
index 00000000..579fb591
--- /dev/null
+++ b/libsigrokdecode4DSL/decoders/pjon/__init__.py
@@ -0,0 +1,25 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2020 Gerhard Sittig <gerhard.sittig@gmx.net>
+##
+## 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/>.
+##
+
+'''
+This protocol decoder interprets the PJON protocol on top of the PJDL
+link layer (and potentially other link layers).
+'''
+
+from .pd import Decoder
diff --git a/libsigrokdecode4DSL/decoders/pjon/pd.py b/libsigrokdecode4DSL/decoders/pjon/pd.py
new file mode 100644
index 00000000..b23cfb84
--- /dev/null
+++ b/libsigrokdecode4DSL/decoders/pjon/pd.py
@@ -0,0 +1,603 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2020 Gerhard Sittig <gerhard.sittig@gmx.net>
+##
+## 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/>.
+##
+
+# See the https://www.pjon.org/ PJON project page and especially the
+# https://www.pjon.org/PJON-protocol-specification-v3.2.php protocol
+# specification, which can use different link layers.
+
+# TODO
+# - Check for the correct order of optional fields (the spec is not as
+#   explicit on these details as I'd expect).
+# - Check decoder's robustness, completeness, and correctness when more
+#   captures become available. Currently there are only few, which only
+#   cover minimal communication, and none of the protocol's flexibility.
+#   The decoder was essentially written based on the available docs, and
+#   then took some arbitrary choices and liberties to cope with real life
+#   data from an example setup. Strictly speaking this decoder violates
+#   the spec, and errs towards the usability side.
+
+import sigrokdecode as srd
+import struct
+
+ANN_RX_INFO, ANN_HDR_CFG, ANN_PKT_LEN, ANN_META_CRC, ANN_TX_INFO, \
+ANN_SVC_ID, ANN_PKT_ID, ANN_ANON_DATA, ANN_PAYLOAD, ANN_END_CRC, \
+ANN_SYN_RSP, \
+ANN_RELATION, \
+ANN_WARN, \
+    = range(13)
+
+def calc_crc8(data):
+    crc = 0
+    for b in data:
+        crc ^= b
+        for i in range(8):
+            odd = crc % 2
+            crc >>= 1
+            if odd:
+                crc ^= 0x97
+    return crc
+
+def calc_crc32(data):
+    crc = 0xffffffff
+    for b in data:
+        crc ^= b
+        for i in range(8):
+            odd = crc % 2
+            crc >>= 1
+            if odd:
+                crc ^= 0xedb88320
+    crc ^= 0xffffffff
+    return crc
+
+class Decoder(srd.Decoder):
+    api_version = 3
+    id = 'pjon'
+    name = 'PJON'
+    longname = 'PJON'
+    desc = 'The PJON protocol.'
+    license = 'gplv2+'
+    inputs = ['pjon_link']
+    outputs = []
+    tags = ['Embedded/industrial']
+    annotations = (
+        ('rx_info', 'Receiver ID'),
+        ('hdr_cfg', 'Header config'),
+        ('pkt_len', 'Packet length'),
+        ('meta_crc', 'Meta CRC'),
+        ('tx_info', 'Sender ID'),
+        ('port', 'Service ID'),
+        ('pkt_id', 'Packet ID'),
+        ('anon', 'Anonymous data'),
+        ('payload', 'Payload'),
+        ('end_crc', 'End CRC'),
+        ('syn_rsp', 'Sync response'),
+        ('relation', 'Relation'),
+        ('warning', 'Warning'),
+    )
+    annotation_rows = (
+        ('fields', 'Fields', (
+            ANN_RX_INFO, ANN_HDR_CFG, ANN_PKT_LEN, ANN_META_CRC, ANN_TX_INFO,
+            ANN_SVC_ID, ANN_ANON_DATA, ANN_PAYLOAD, ANN_END_CRC, ANN_SYN_RSP,
+        )),
+        ('relations', 'Relations', (ANN_RELATION,)),
+        ('warnings', 'Warnings', (ANN_WARN,)),
+    )
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.reset_frame()
+
+    def reset_frame(self):
+        self.frame_ss = None
+        self.frame_es = None
+        self.frame_rx_id = None
+        self.frame_tx_id = None
+        self.frame_payload_text = None
+        self.frame_bytes = None
+        self.frame_has_ack = None
+        self.ack_bytes = None
+        self.ann_ss = None
+        self.ann_es = None
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def putg(self, ss, es, ann, data):
+        self.put(ss, es, self.out_ann, [ann, data])
+
+    def frame_flush(self):
+        if not self.frame_bytes:
+            return
+        if not self.frame_ss or not self.frame_es:
+            return
+
+        # Emit "communication relation" details.
+        # TODO Include the service ID (port number) as well?
+        text = []
+        if self.frame_rx_id is not None:
+            text.append("RX {}".format(self.frame_rx_id[-1]))
+        if self.frame_tx_id is not None:
+            text.append("TX {}".format(self.frame_tx_id[-1]))
+        if self.frame_payload_text is not None:
+            text.append("DATA {}".format(self.frame_payload_text))
+        if self.frame_has_ack is not None:
+            text.append("ACK {:02x}".format(self.frame_has_ack))
+        if text:
+            text = " - ".join(text)
+            self.putg(self.frame_ss, self.frame_es, ANN_RELATION, [text])
+
+    def handle_field_get_desc(self, idx = None):
+        '''Lookup description of a PJON frame field.'''
+        if not self.field_desc:
+            return None
+        if idx is None:
+            idx = self.field_desc_idx
+        if idx >= 0 and idx >= len(self.field_desc):
+            return None
+        if idx < 0 and abs(idx) > len(self.field_desc):
+            return None
+        desc = self.field_desc[idx]
+        return desc
+
+    def handle_field_add_desc(self, fmt, hdl, cls = None):
+        '''Register description for a PJON frame field.'''
+        item = {
+            'format': fmt,
+            'width': struct.calcsize(fmt),
+            'handler': hdl,
+            'anncls': cls,
+        }
+        self.field_desc.append(item)
+
+    def handle_field_seed_desc(self):
+        '''Seed list of PJON frame fields' descriptions.'''
+
+        # At the start of a PJON frame, the layout of only two fields
+        # is known. Subsequent fields (their presence, and width) depend
+        # on the content of the header config field.
+
+        self.field_desc = []
+        self.handle_field_add_desc('<B', self.handle_field_rx_id, ANN_RX_INFO)
+        self.handle_field_add_desc('<B', self.handle_field_config, ANN_HDR_CFG)
+
+        self.field_desc_idx = 0
+        self.field_desc_got = 0
+
+        self.frame_ss = None
+        self.frame_es = None
+        self.frame_rx_id = None
+        self.frame_is_broadcast = None
+        self.frame_tx_id = None
+        self.frame_payload = None
+        self.frame_payload_text = None
+        self.frame_has_ack = None
+
+    def handle_field_rx_id(self, b):
+        '''Process receiver ID field of a PJON frame.'''
+
+        b = b[0]
+
+        # Provide text presentation, caller emits frame field annotation.
+        if b == 255: # "not assigned"
+            id_txt = 'NA'
+        elif b == 0: # "broadcast"
+            id_txt = 'BC'
+        else: # unicast
+            id_txt = '{:d}'.format(b)
+        texts = [
+            'RX_ID {}'.format(id_txt),
+            '{}'.format(id_txt),
+        ]
+
+        # Track RX info for communication relation emission.
+        self.frame_rx_id = (b, id_txt)
+        self.frame_is_broadcast = b == 0
+
+        return texts
+
+    def handle_field_config(self, b):
+        '''Process header config field of a PJON frame.'''
+
+        # Caller provides a list of values. We want a single scalar.
+        b = b[0]
+
+        # Get the config flags.
+        self.cfg_shared = b & (1 << 0)
+        self.cfg_tx_info = b & (1 << 1)
+        self.cfg_sync_ack = b & (1 << 2)
+        self.cfg_async_ack = b & (1 << 3)
+        self.cfg_port = b & (1 << 4)
+        self.cfg_crc32 = b & (1 << 5)
+        self.cfg_len16 = b & (1 << 6)
+        self.cfg_pkt_id = b & (1 << 7)
+
+        # Get a textual presentation of the flags.
+        text = []
+        text.append('pkt_id' if self.cfg_pkt_id else '-') # packet number
+        text.append('len16' if self.cfg_len16 else '-') # 16bit length not 8bit
+        text.append('crc32' if self.cfg_crc32 else '-') # 32bit CRC not 8bit
+        text.append('svc_id' if self.cfg_port else '-') # port aka service ID
+        text.append('ack_mode' if self.cfg_async_ack else '-') # async response
+        text.append('ack' if self.cfg_sync_ack else '-') # synchronous response
+        text.append('tx_info' if self.cfg_tx_info else '-') # sender address
+        text.append('bus_id' if self.cfg_shared else '-') # "shared" vs "local"
+        text = ' '.join(text)
+        bits = '{:08b}'.format(b)
+        texts = [
+            'CFG {:s}'.format(text),
+            'CFG {}'.format(bits),
+            bits
+        ]
+
+        # TODO Come up with the most appropriate phrases for this logic.
+        # Are separate instruction groups with repeated conditions more
+        # readable than one common block which registers fields _and_
+        # updates the overhead size? Or is the latter preferrable due to
+        # easier maintenance and less potential for inconsistency?
+
+        # Get the size of variable width fields, to calculate the size
+        # of the packet overhead (the part that is not the payload data).
+        # This lets us derive the payload length when we later receive
+        # the frame's total length.
+        u8_fmt = '>B'
+        u16_fmt = '>H'
+        u32_fmt = '>L'
+        len_fmt = u16_fmt if self.cfg_len16 else u8_fmt
+        bus_fmt = '>4B'
+        crc_fmt = u32_fmt if self.cfg_crc32 else u8_fmt
+        self.cfg_overhead = 0
+        self.cfg_overhead += struct.calcsize(u8_fmt) # receiver ID
+        self.cfg_overhead += struct.calcsize(u8_fmt) # header config
+        self.cfg_overhead += struct.calcsize(len_fmt) # packet length
+        self.cfg_overhead += struct.calcsize(u8_fmt) # initial CRC, always CRC8
+        # TODO Check for completeness and correctness.
+        if self.cfg_shared:
+            self.cfg_overhead += struct.calcsize(u32_fmt) # receiver bus
+        if self.cfg_tx_info:
+            if self.cfg_shared:
+                self.cfg_overhead += struct.calcsize(u32_fmt) # sender bus
+            self.cfg_overhead += struct.calcsize(u8_fmt) # sender ID
+        if self.cfg_port:
+            self.cfg_overhead += struct.calcsize(u16_fmt) # service ID
+        if self.cfg_pkt_id:
+            self.cfg_overhead += struct.calcsize(u16_fmt) # packet ID
+        self.cfg_overhead += struct.calcsize(crc_fmt) # end CRC
+
+        # Register more frame fields as we learn about their presence and
+        # format. Up to this point only receiver ID and header config were
+        # registered since their layout is fixed.
+        #
+        # Packet length and meta CRC are always present but can be of
+        # variable width. Optional fields follow the meta CRC and preceed
+        # the payload bytes. Notice that payload length isn't known here
+        # either, though its position is known already. The packet length
+        # is yet to get received. Subtracting the packet overhead from it
+        # (which depends on the header configuration) will provide that
+        # information.
+        #
+        # TODO Check for completeness and correctness.
+        # TODO Optionally fold overhead size arith and field registration
+        # into one block of instructions, to reduce the redundancy in the
+        # condition checks, and raise awareness for incomplete sequences
+        # during maintenance.
+        self.handle_field_add_desc(len_fmt, self.handle_field_pkt_len, ANN_PKT_LEN)
+        self.handle_field_add_desc(u8_fmt, self.handle_field_meta_crc, ANN_META_CRC)
+        if self.cfg_shared:
+            self.handle_field_add_desc(bus_fmt, self.handle_field_rx_bus, ANN_ANON_DATA)
+        if self.cfg_tx_info:
+            if self.cfg_shared:
+                self.handle_field_add_desc(bus_fmt, self.handle_field_tx_bus, ANN_ANON_DATA)
+            self.handle_field_add_desc(u8_fmt, self.handle_field_tx_id, ANN_ANON_DATA)
+        if self.cfg_port:
+            self.handle_field_add_desc(u16_fmt, ['PORT {:d}', '{:d}'], ANN_ANON_DATA)
+        if self.cfg_pkt_id:
+            self.handle_field_add_desc(u16_fmt, ['PKT {:04x}', '{:04x}'], ANN_ANON_DATA)
+        pl_fmt = '>{:d}B'.format(0)
+        self.handle_field_add_desc(pl_fmt, self.handle_field_payload, ANN_PAYLOAD)
+        self.handle_field_add_desc(crc_fmt, self.handle_field_end_crc, ANN_END_CRC)
+
+        # Emit warning annotations for invalid flag combinations.
+        warn_texts = []
+        wants_ack = self.cfg_sync_ack or self.cfg_async_ack
+        if wants_ack and not self.cfg_tx_info:
+            warn_texts.append('ACK request without TX info')
+        if wants_ack and self.frame_is_broadcast:
+            warn_texts.append('ACK request for broadcast')
+        if self.cfg_sync_ack and self.cfg_async_ack:
+            warn_texts.append('sync and async ACK request')
+        if self.cfg_len16 and not self.cfg_crc32:
+            warn_texts.append('extended length needs CRC32')
+        if warn_texts:
+            warn_texts = ', '.join(warn_texts)
+            self.putg(self.ann_ss, self.ann_es, ANN_WARN, [warn_texts])
+
+        # Have the caller emit the annotation for configuration data.
+        return texts
+
+    def handle_field_pkt_len(self, b):
+        '''Process packet length field of a PJON frame.'''
+
+        # Caller provides a list of values. We want a single scalar.
+        b = b[0]
+
+        # The wire communicates the total packet length. Some of it is
+        # overhead (non-payload data), while its volume is variable in
+        # size (depends on the header configuration).
+        #
+        # Derive the payload size from previously observed flags. Update
+        # the previously registered field description (the second last
+        # item in the list, before the end CRC).
+
+        pkt_len = b
+        pl_len = b - self.cfg_overhead
+        warn_texts = []
+        if pkt_len not in range(self.cfg_overhead, 65536):
+            warn_texts.append('suspicious packet length')
+        if pkt_len > 15 and not self.cfg_crc32:
+            warn_texts.append('length above 15 needs CRC32')
+        if pl_len < 1:
+            warn_texts.append('suspicious payload length')
+            pl_len = 0
+        if warn_texts:
+            warn_texts = ', '.join(warn_texts)
+            self.putg(self.ann_ss, self.ann_es, ANN_WARN, [warn_texts])
+        pl_fmt = '>{:d}B'.format(pl_len)
+
+        desc = self.handle_field_get_desc(-2)
+        desc['format'] = pl_fmt
+        desc['width'] = struct.calcsize(pl_fmt)
+
+        # Have the caller emit the annotation for the packet length.
+        # Provide information of different detail level for zooming.
+        texts = [
+            'LENGTH {:d} (PAYLOAD {:d})'.format(pkt_len, pl_len),
+            'LEN {:d} (PL {:d})'.format(pkt_len, pl_len),
+            '{:d} ({:d})'.format(pkt_len, pl_len),
+            '{:d}'.format(pkt_len),
+        ]
+        return texts
+
+    def handle_field_common_crc(self, have, is_meta):
+        '''Process a CRC field of a PJON frame.'''
+
+        # CRC algorithm and width are configurable, and can differ
+        # across meta and end checksums in a frame's fields.
+        caption = 'META' if is_meta else 'END'
+        crc_len = 8 if is_meta else 32 if self.cfg_crc32 else 8
+        crc_bytes = crc_len // 8
+        crc_fmt = '{:08x}' if crc_len == 32 else '{:02x}'
+        have_text = crc_fmt.format(have)
+
+        # Check received against expected checksum. Emit warnings.
+        warn_texts = []
+        data = self.frame_bytes[:-crc_bytes]
+        want = calc_crc32(data) if crc_len == 32 else calc_crc8(data)
+        if want != have:
+            want_text = crc_fmt.format(want)
+            warn_texts.append('CRC mismatch - want {} have {}'.format(want_text, have_text))
+        if warn_texts:
+            warn_texts = ', '.join(warn_texts)
+            self.putg(self.ann_ss, self.ann_es, ANN_WARN, [warn_texts])
+
+        # Provide text representation for frame field, caller emits
+        # the annotation.
+        texts = [
+            '{}_CRC {}'.format(caption, have_text),
+            'CRC {}'.format(have_text),
+            have_text,
+        ]
+        return texts
+
+    def handle_field_meta_crc(self, b):
+        '''Process initial CRC (meta) field of a PJON frame.'''
+        # Caller provides a list of values. We want a single scalar.
+        b = b[0]
+        return self.handle_field_common_crc(b, True)
+
+    def handle_field_end_crc(self, b):
+        '''Process end CRC (total frame) field of a PJON frame.'''
+        # Caller provides a list of values. We want a single scalar.
+        b = b[0]
+        return self.handle_field_common_crc(b, False)
+
+    def handle_field_common_bus(self, b):
+        '''Common handling of bus ID details. Used for RX and TX.'''
+        bus_id = b[:4]
+        bus_num = struct.unpack('>L', bytearray(bus_id))
+        bus_txt = '.'.join(['{:d}'.format(b) for b in bus_id])
+        return bus_num, bus_txt
+
+    def handle_field_rx_bus(self, b):
+        '''Process receiver bus ID field of a PJON frame.'''
+
+        # When we get here, there always should be an RX ID already.
+        bus_num, bus_txt = self.handle_field_common_bus(b[:4])
+        rx_txt = "{} {}".format(bus_txt, self.frame_rx_id[-1])
+        self.frame_rx_id = (bus_num, self.frame_rx_id[0], rx_txt)
+
+        # Provide text representation for frame field, caller emits
+        # the annotation.
+        texts = [
+            'RX_BUS {}'.format(bus_txt),
+            bus_txt,
+        ]
+        return texts
+
+    def handle_field_tx_bus(self, b):
+        '''Process transmitter bus ID field of a PJON frame.'''
+
+        # The TX ID field is optional, as is the use of bus ID fields.
+        # In the TX info case the TX bus ID is seen before the TX ID.
+        bus_num, bus_txt = self.handle_field_common_bus(b[:4])
+        self.frame_tx_id = (bus_num, None, bus_txt)
+
+        # Provide text representation for frame field, caller emits
+        # the annotation.
+        texts = [
+            'TX_BUS {}'.format(bus_txt),
+            bus_txt,
+        ]
+        return texts
+
+    def handle_field_tx_id(self, b):
+        '''Process transmitter ID field of a PJON frame.'''
+
+        b = b[0]
+
+        id_txt = "{:d}".format(b)
+        if self.frame_tx_id is None:
+            self.frame_tx_id = (b, id_txt)
+        else:
+            tx_txt = "{} {}".format(self.frame_tx_id[-1], id_txt)
+            self.frame_tx_id = (self.frame_tx_id[0], b, tx_txt)
+
+        # Provide text representation for frame field, caller emits
+        # the annotation.
+        texts = [
+            'TX_ID {}'.format(id_txt),
+            id_txt,
+        ]
+        return texts
+
+    def handle_field_payload(self, b):
+        '''Process payload data field of a PJON frame.'''
+
+        text = ' '.join(['{:02x}'.format(v) for v in b])
+        self.frame_payload = b[:]
+        self.frame_payload_text = text
+
+        texts = [
+            'PAYLOAD {}'.format(text),
+            text,
+        ]
+        return texts
+
+    def handle_field_sync_resp(self, b):
+        '''Process synchronous response for a PJON frame.'''
+
+        self.frame_has_ack = b
+
+        texts = [
+            'ACK {:02x}'.format(b),
+            '{:02x}'.format(b),
+        ]
+        return texts
+
+    def decode(self, ss, es, data):
+        ptype, pdata = data
+
+        # Start frame bytes accumulation when FRAME_INIT is seen. Flush
+        # previously accumulated frame bytes when a new frame starts.
+        if ptype == 'FRAME_INIT':
+            self.frame_flush()
+            self.reset_frame()
+            self.frame_bytes = []
+            self.handle_field_seed_desc()
+            self.frame_ss = ss
+            self.frame_es = es
+            return
+
+        # Use IDLE as another (earlier) trigger to flush frames. Also
+        # trigger flushes on FRAME-DATA which mean that the link layer
+        # inspection has seen the end of a protocol frame.
+        #
+        # TODO Improve usability? Emit warnings for PJON frames where
+        # FRAME_DATA was seen but FRAME_INIT wasn't? So that users can
+        # become aware of broken frames.
+        if ptype in ('IDLE', 'FRAME_DATA'):
+            self.frame_flush()
+            self.reset_frame()
+            return
+
+        # Switch from data bytes to response bytes when WAIT is seen.
+        if ptype == 'SYNC_RESP_WAIT':
+            self.ack_bytes = []
+            self.ann_ss, self.ann_es = None, None
+            return
+
+        # Accumulate data bytes as they arrive. Put them in the bucket
+        # which corresponds to its most recently seen leader.
+        if ptype == 'DATA_BYTE':
+            b = pdata
+            self.frame_es = es
+
+            # Are we collecting response bytes (ACK)?
+            if self.ack_bytes is not None:
+                if not self.ann_ss:
+                    self.ann_ss = ss
+                self.ack_bytes.append(b)
+                self.ann_es = es
+                text = self.handle_field_sync_resp(b)
+                if text:
+                    self.putg(self.ann_ss, self.ann_es, ANN_SYN_RSP, text)
+                self.ann_ss, self.ann_es = None, None
+                return
+
+            # Are we collecting frame content?
+            if self.frame_bytes is not None:
+                if not self.ann_ss:
+                    self.ann_ss = ss
+                self.frame_bytes.append(b)
+                self.ann_es = es
+
+                # Has the field value become available yet?
+                desc = self.handle_field_get_desc()
+                if not desc:
+                    return
+                width = desc.get('width', None)
+                if not width:
+                    return
+                self.field_desc_got += 1
+                if self.field_desc_got != width:
+                    return
+
+                # Grab most recent received field as a byte array. Get
+                # the values that it contains.
+                fmt = desc.get('format', '>B')
+                raw = bytearray(self.frame_bytes[-width:])
+                values = struct.unpack(fmt, raw)
+
+                # Process the value, and get its presentation. Can be
+                # mere formatting, or serious execution of logic.
+                hdl = desc.get('handler', '{!r}')
+                if isinstance(hdl, str):
+                    text = [hdl.format(*values)]
+                elif isinstance(hdl, (list, tuple)):
+                    text = [f.format(*values) for f in hdl]
+                elif hdl:
+                    text = hdl(values)
+                cls = desc.get('anncls', ANN_ANON_DATA)
+
+                # Emit annotation unless the handler routine already did.
+                if cls is not None and text:
+                    self.putg(self.ann_ss, self.ann_es, cls, text)
+                self.ann_ss, self.ann_es = None, None
+
+                # Advance scan position for to-get-received field.
+                self.field_desc_idx += 1
+                self.field_desc_got = 0
+                return
+
+            # Unknown phase, not collecting. Not synced yet to the input?
+            return
+
+        # Unknown or unhandled kind of link layer output.
+        return