[libsigrokdecode.git] / decoders / lin / pd.py

##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2018 Stephan Thiele <stephan.thiele@mailbox.org>
##
## 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

class LinFsm:
    class State:
        WaitForBreak = 'WAIT FOR BREAK'
        Sync = 'SYNC'
        Pid = 'PID'
        Data = 'DATA'
        Checksum = 'CHECKSUM'
        Error = 'ERROR'

    def transit(self, target_state):
        if not self._transition_allowed(target_state):
            return False
        self.state = target_state
        return True

    def _transition_allowed(self, target_state):
        if target_state == LinFsm.State.Error:
            return True
        return target_state in self.allowed_state[self.state]

    def reset(self):
        self.state = LinFsm.State.WaitForBreak

    def __init__(self):
        self.allowed_state = dict()
        self.allowed_state[LinFsm.State.WaitForBreak] = (LinFsm.State.Sync,)
        self.allowed_state[LinFsm.State.Sync]         = (LinFsm.State.Pid,)
        self.allowed_state[LinFsm.State.Pid]          = (LinFsm.State.Data,)
        self.allowed_state[LinFsm.State.Data]         = (LinFsm.State.Data, LinFsm.State.Checksum)
        self.allowed_state[LinFsm.State.Checksum]     = (LinFsm.State.WaitForBreak,)
        self.allowed_state[LinFsm.State.Error]        = (LinFsm.State.Sync,)

        self.state = None
        self.reset()

class Decoder(srd.Decoder):
    api_version = 3
    id = 'lin'
    name = 'LIN'
    longname = 'Local Interconnect Network'
    desc = 'Local Interconnect Network (LIN) protocol.'
    license = 'gplv2+'
    inputs = ['uart']
    outputs = ['lin']
    options = (
        {'id': 'version', 'desc': 'Protocol version', 'default': 2, 'values': (1, 2)},
    )
    annotations = (
        ('data', 'LIN data'),
        ('control', 'Protocol info'),
        ('error', 'Error descriptions'),
        ('inline_error', 'Protocol violations and errors'),
    )
    annotation_rows = (
        ('data', 'Data', (0, 1, 3)),
        ('error', 'Error', (2,)),
    )

    def __init__(self):
        self.reset()

    def reset(self):
        self.fsm = LinFsm()
        self.lin_header = []
        self.lin_rsp = []
        self.lin_version = None
        self.out_ann = None
        self.ss_block = None
        self.es_block = None

    def start(self):
        self.out_ann = self.register(srd.OUTPUT_ANN)
        self.lin_version = self.options['version']

    def putx(self, data):
        self.put(self.ss_block, self.es_block, self.out_ann, data)

    def wipe_break_null_byte(self, value):
        # Upon a break condition a null byte is received which must be ignored.
        if self.fsm.state != LinFsm.State.WaitForBreak and self.fsm.state != LinFsm.State.Error:
            if len(self.lin_rsp):
                value = self.lin_rsp.pop()[2]
            else:
                self.lin_header.pop()

        if value != 0:
            self.fsm.transit(LinFsm.State.Error)
            self.handle_error()
            return False

        return True

    def handle_wait_for_break(self, value):
        self.wipe_break_null_byte(value)

    def handle_break(self, value):
        if self.fsm.state != LinFsm.State.WaitForBreak and self.fsm.state != LinFsm.State.Error:
            if self.wipe_break_null_byte(value):
                self.fsm.transit(LinFsm.State.Checksum)
                self.handle_checksum()

        self.fsm.reset()
        self.fsm.transit(LinFsm.State.Sync)

        self.putx([1, ['Break condition', 'Break', 'Brk', 'B']])

    def handle_sync(self, value):
        self.fsm.transit(LinFsm.State.Pid)
        self.lin_header.append((self.ss_block, self.es_block, value))

    def handle_pid(self, value):
        self.fsm.transit(LinFsm.State.Data)
        self.lin_header.append((self.ss_block, self.es_block, value))

    def handle_data(self, value):
        self.lin_rsp.append((self.ss_block, self.es_block, value))

    def handle_checksum(self):
        sync = self.lin_header.pop(0) if len(self.lin_header) else None

        self.put(sync[0], sync[1], self.out_ann, [0, ['Sync', 'S']])

        if sync[2] != 0x55:
            self.put(sync[0], sync[1], self.out_ann,
                     [2, ['Sync is not 0x55', 'Not 0x55', '!= 0x55']])

        pid = self.lin_header.pop(0) if len(self.lin_header) else None
        checksum = self.lin_rsp.pop() if len(self.lin_rsp) else None

        if pid:
            id = pid[2] & 0x3F
            parity = pid[2] >> 6

            expected_parity = self.calc_parity(pid[2])
            parity_valid = parity == expected_parity

            if not parity_valid:
                self.put(pid[0], pid[1], self.out_ann, [2, ['P != %d' % expected_parity]])

            ann_class = 0 if parity_valid else 3
            self.put(pid[0], pid[1], self.out_ann, [ann_class, [
                'ID: %02X Parity: %d (%s)' % (id, parity, 'ok' if parity_valid else 'bad'),
                'ID: 0x%02X' % id, 'I: %d' % id
            ]])

        if len(self.lin_rsp):
            checksum_valid = self.checksum_is_valid(pid[2], self.lin_rsp, checksum[2])

            for b in self.lin_rsp:
                self.put(b[0], b[1], self.out_ann, [0, ['Data: 0x%02X' % b[2], 'D: 0x%02X' % b[2]]])

            ann_class = 0 if checksum_valid else 3
            self.put(checksum[0], checksum[1], self.out_ann,
                 [ann_class, ['Checksum: 0x%02X' % checksum[2], 'Checksum', 'Chk', 'C']])

            if not checksum_valid:
                self.put(checksum[0], checksum[1], self.out_ann, [2, ['Checksum invalid']])
        else:
            pass # No response.

        self.lin_header.clear()
        self.lin_rsp.clear()

    def handle_error(self):
        self.putx([3, ['Error', 'Err', 'E']])

    def checksum_is_valid(self, pid, data, checksum):
        if self.lin_version == 2:
            id = pid & 0x3F

            if id != 60 and id != 61:
                checksum += pid

        for d in data:
            checksum += d[2]

        carry_bits = int(checksum / 256)
        checksum += carry_bits

        return checksum & 0xFF == 0xFF

    @staticmethod
    def calc_parity(pid):
        id = [((pid & 0x3F) >> i) & 1 for i in range(8)]

        p0 = id[0] ^ id[1] ^ id[2] ^ id[4]
        p1 = not (id[1] ^ id[3] ^ id[4] ^ id[5])

        return (p0 << 0) | (p1 << 1)

    def decode(self, ss, es, data):
        ptype, rxtx, pdata = data

        self.ss_block, self.es_block = ss, es

        # Ignore all UART packets except the actual data packets or BREAK.
        if ptype == 'BREAK':
            self.handle_break(pdata)
        if ptype != 'DATA':
            return

        # We're only interested in the byte value (not individual bits).
        pdata = pdata[0]

        # Short LIN overview:
        #  - Message begins with a BREAK (0x00) for at least 13 bittimes.
        #  - Break is always followed by a SYNC byte (0x55).
        #  - Sync byte is followed by a PID byte (Protected Identifier).
        #  - PID byte is followed by 1 - 8 data bytes and a final checksum byte.

        if   self.fsm.state == LinFsm.State.Error:        self.handle_error()
        elif self.fsm.state == LinFsm.State.WaitForBreak: self.handle_wait_for_break(pdata)
        elif self.fsm.state == LinFsm.State.Sync:         self.handle_sync(pdata)
        elif self.fsm.state == LinFsm.State.Pid:          self.handle_pid(pdata)
        elif self.fsm.state == LinFsm.State.Data:         self.handle_data(pdata)
        elif self.fsm.state == LinFsm.State.Checksum:     self.handle_checksum()
Commit	Line	Data
fe9160d5	1	##
	2	## This file is part of the libsigrokdecode project.
	3	##
	4	## Copyright (C) 2018 Stephan Thiele <stephan.thiele@mailbox.org>
	5	##
	6	## This program is free software; you can redistribute it and/or modify
	7	## it under the terms of the GNU General Public License as published by
	8	## the Free Software Foundation; either version 2 of the License, or
	9	## (at your option) any later version.
	10	##
	11	## This program is distributed in the hope that it will be useful,
	12	## but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	## GNU General Public License for more details.
	15	##
	16	## You should have received a copy of the GNU General Public License
	17	## along with this program; if not, see <http://www.gnu.org/licenses/>.
	18	##
	19
	20	import sigrokdecode as srd
	21
	22	class LinFsm:
	23	class State:
	24	WaitForBreak = 'WAIT FOR BREAK'
	25	Sync = 'SYNC'
	26	Pid = 'PID'
	27	Data = 'DATA'
	28	Checksum = 'CHECKSUM'
	29	Error = 'ERROR'
	30
	31	def transit(self, target_state):
	32	if not self._transition_allowed(target_state):
	33	return False
	34	self.state = target_state
	35	return True
	36
	37	def _transition_allowed(self, target_state):
	38	if target_state == LinFsm.State.Error:
	39	return True
b1e3616d	40	return target_state in self.allowed_state[self.state]
fe9160d5	41
	42	def reset(self):
	43	self.state = LinFsm.State.WaitForBreak
	44
	45	def __init__(self):
	46	self.allowed_state = dict()
	47	self.allowed_state[LinFsm.State.WaitForBreak] = (LinFsm.State.Sync,)
	48	self.allowed_state[LinFsm.State.Sync] = (LinFsm.State.Pid,)
	49	self.allowed_state[LinFsm.State.Pid] = (LinFsm.State.Data,)
	50	self.allowed_state[LinFsm.State.Data] = (LinFsm.State.Data, LinFsm.State.Checksum)
	51	self.allowed_state[LinFsm.State.Checksum] = (LinFsm.State.WaitForBreak,)
	52	self.allowed_state[LinFsm.State.Error] = (LinFsm.State.Sync,)
	53
	54	self.state = None
	55	self.reset()
	56
	57	class Decoder(srd.Decoder):
	58	api_version = 3
	59	id = 'lin'
	60	name = 'LIN'
	61	longname = 'Local Interconnect Network'
	62	desc = 'Local Interconnect Network (LIN) protocol.'
	63	license = 'gplv2+'
	64	inputs = ['uart']
	65	outputs = ['lin']
	66	options = (
	67	{'id': 'version', 'desc': 'Protocol version', 'default': 2, 'values': (1, 2)},
	68	)
	69	annotations = (
	70	('data', 'LIN data'),
	71	('control', 'Protocol info'),
	72	('error', 'Error descriptions'),
	73	('inline_error', 'Protocol violations and errors'),
	74	)
	75	annotation_rows = (
	76	('data', 'Data', (0, 1, 3)),
	77	('error', 'Error', (2,)),
	78	)
	79
	80	def __init__(self):
	81	self.reset()
	82
	83	def reset(self):
	84	self.fsm = LinFsm()
	85	self.lin_header = []
	86	self.lin_rsp = []
	87	self.lin_version = None
	88	self.out_ann = None
	89	self.ss_block = None
	90	self.es_block = None
	91
	92	def start(self):
	93	self.out_ann = self.register(srd.OUTPUT_ANN)
	94	self.lin_version = self.options['version']
	95
	96	def putx(self, data):
	97	self.put(self.ss_block, self.es_block, self.out_ann, data)
	98
	99	def wipe_break_null_byte(self, value):
	100	# Upon a break condition a null byte is received which must be ignored.
	101	if self.fsm.state != LinFsm.State.WaitForBreak and self.fsm.state != LinFsm.State.Error:
	102	if len(self.lin_rsp):
	103	value = self.lin_rsp.pop()[2]
	104	else:
105	self.lin_header.pop()
106
107	if value != 0:
108	self.fsm.transit(LinFsm.State.Error)
109	self.handle_error()
110	return False
111
112	return True
113
114	def handle_wait_for_break(self, value):
115	self.wipe_break_null_byte(value)
116
117	def handle_break(self, value):
118	if self.fsm.state != LinFsm.State.WaitForBreak and self.fsm.state != LinFsm.State.Error:
119	if self.wipe_break_null_byte(value):
120	self.fsm.transit(LinFsm.State.Checksum)
121	self.handle_checksum()
122
123	self.fsm.reset()
124	self.fsm.transit(LinFsm.State.Sync)
125
740a49d4	126	self.putx([1, ['Break condition', 'Break', 'Brk', 'B']])
fe9160d5	127
	128	def handle_sync(self, value):
	129	self.fsm.transit(LinFsm.State.Pid)
	130	self.lin_header.append((self.ss_block, self.es_block, value))
	131
	132	def handle_pid(self, value):
	133	self.fsm.transit(LinFsm.State.Data)
	134	self.lin_header.append((self.ss_block, self.es_block, value))
	135
	136	def handle_data(self, value):
	137	self.lin_rsp.append((self.ss_block, self.es_block, value))
	138
	139	def handle_checksum(self):
	140	sync = self.lin_header.pop(0) if len(self.lin_header) else None
	141
	142	self.put(sync[0], sync[1], self.out_ann, [0, ['Sync', 'S']])
	143
	144	if sync[2] != 0x55:
	145	self.put(sync[0], sync[1], self.out_ann,
	146	[2, ['Sync is not 0x55', 'Not 0x55', '!= 0x55']])
	147
	148	pid = self.lin_header.pop(0) if len(self.lin_header) else None
	149	checksum = self.lin_rsp.pop() if len(self.lin_rsp) else None
	150
	151	if pid:
	152	id = pid[2] & 0x3F
	153	parity = pid[2] >> 6
	154
	155	expected_parity = self.calc_parity(pid[2])
	156	parity_valid = parity == expected_parity
	157
	158	if not parity_valid:
	159	self.put(pid[0], pid[1], self.out_ann, [2, ['P != %d' % expected_parity]])
	160
	161	ann_class = 0 if parity_valid else 3
	162	self.put(pid[0], pid[1], self.out_ann, [ann_class, [
	163	'ID: %02X Parity: %d (%s)' % (id, parity, 'ok' if parity_valid else 'bad'),
	164	'ID: 0x%02X' % id, 'I: %d' % id
	165	]])
	166
	167	if len(self.lin_rsp):
	168	checksum_valid = self.checksum_is_valid(pid[2], self.lin_rsp, checksum[2])
	169
	170	for b in self.lin_rsp:
	171	self.put(b[0], b[1], self.out_ann, [0, ['Data: 0x%02X' % b[2], 'D: 0x%02X' % b[2]]])
	172
	173	ann_class = 0 if checksum_valid else 3
	174	self.put(checksum[0], checksum[1], self.out_ann,
	175	[ann_class, ['Checksum: 0x%02X' % checksum[2], 'Checksum', 'Chk', 'C']])
	176
	177	if not checksum_valid:
	178	self.put(checksum[0], checksum[1], self.out_ann, [2, ['Checksum invalid']])
	179	else:
	180	pass # No response.
	181
	182	self.lin_header.clear()
	183	self.lin_rsp.clear()
	184
	185	def handle_error(self):
	186	self.putx([3, ['Error', 'Err', 'E']])
	187
	188	def checksum_is_valid(self, pid, data, checksum):
	189	if self.lin_version == 2:
	190	id = pid & 0x3F
191
192	if id != 60 and id != 61:
193	checksum += pid
194
195	for d in data:
196	checksum += d[2]
197
198	carry_bits = int(checksum / 256)
199	checksum += carry_bits
200
201	return checksum & 0xFF == 0xFF
202
203	@staticmethod
204	def calc_parity(pid):
205	id = [((pid & 0x3F) >> i) & 1 for i in range(8)]
206
207	p0 = id[0] ^ id[1] ^ id[2] ^ id[4]
208	p1 = not (id[1] ^ id[3] ^ id[4] ^ id[5])
209
210	return (p0 << 0) \| (p1 << 1)
211
212	def decode(self, ss, es, data):
213	ptype, rxtx, pdata = data
214
215	self.ss_block, self.es_block = ss, es
216
217	# Ignore all UART packets except the actual data packets or BREAK.
218	if ptype == 'BREAK':
219	self.handle_break(pdata)
220	if ptype != 'DATA':
221	return
222
223	# We're only interested in the byte value (not individual bits).
224	pdata = pdata[0]
225
226	# Short LIN overview:
227	# - Message begins with a BREAK (0x00) for at least 13 bittimes.
228	# - Break is always followed by a SYNC byte (0x55).
229	# - Sync byte is followed by a PID byte (Protected Identifier).
230	# - PID byte is followed by 1 - 8 data bytes and a final checksum byte.
231
232	if self.fsm.state == LinFsm.State.Error: self.handle_error()
233	elif self.fsm.state == LinFsm.State.WaitForBreak: self.handle_wait_for_break(pdata)
234	elif self.fsm.state == LinFsm.State.Sync: self.handle_sync(pdata)
235	elif self.fsm.state == LinFsm.State.Pid: self.handle_pid(pdata)
236	elif self.fsm.state == LinFsm.State.Data: self.handle_data(pdata)
237	elif self.fsm.state == LinFsm.State.Checksum: self.handle_checksum()