+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2019 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
+
+# Selection of constants as defined in FlexRay specification 3.0.1 Chapter A.1:
+class Const:
+ cChannelIdleDelimiter = 11
+ cCrcInitA = 0xFEDCBA
+ cCrcInitB = 0xABCDEF
+ cCrcPolynomial = 0x5D6DCB
+ cCrcSize = 24
+ cCycleCountMax = 63
+ cdBSS = 2
+ cdCAS = 30
+ cdFES = 2
+ cdFSS = 1
+ cHCrcInit = 0x01A
+ cHCrcPolynomial = 0x385
+ cHCrcSize = 11
+ cSamplesPerBit = 8
+ cSlotIDMax = 2047
+ cStaticSlotIDMax = 1023
+ cVotingSamples = 5
+
+class SamplerateError(Exception):
+ pass
+
+class Decoder(srd.Decoder):
+ api_version = 3
+ id = 'flexray'
+ name = 'FlexRay'
+ longname = 'FlexRay'
+ desc = 'Automotive network communications protocol.'
+ license = 'gplv2+'
+ inputs = ['logic']
+ outputs = []
+ tags = ['Automotive']
+ channels = (
+ {'id': 'channel', 'name': 'Channel', 'desc': 'FlexRay bus channel'},
+ )
+ options = (
+ {'id': 'channel_type', 'desc': 'Channel type', 'default': 'A',
+ 'values': ('A', 'B')},
+ {'id': 'bitrate', 'desc': 'Bitrate (Mbit/s)', 'default': '10.0',
+ 'values': ('10.0', '5.0', '2.5')},
+ )
+ annotations = (
+ ('data', 'FlexRay payload data'),
+ ('tss', 'Transmission start sequence'),
+ ('fss', 'Frame start sequence'),
+ ('reserved-bit', 'Reserved bit'),
+ ('ppi', 'Payload preamble indicator'),
+ ('null-frame', 'Nullframe indicator'),
+ ('sync-frame', 'Full identifier'),
+ ('startup-frame', 'Startup frame indicator'),
+ ('id', 'Frame ID'),
+ ('length', 'Data length'),
+ ('header-crc', 'Header CRC'),
+ ('cycle', 'Cycle code'),
+ ('data-byte', 'Data byte'),
+ ('frame-crc', 'Frame CRC'),
+ ('cid-delimiter', 'Channel idle delimiter'),
+ ('bss', 'Byte start sequence'),
+ ('warnings', 'Human-readable warnings'),
+ ('bit', 'Bit'),
+ ('cid', 'Channel idle delimiter'),
+ ('dts', 'Dynamic trailing sequence'),
+ ('cas', 'Collision avoidance symbol'),
+ )
+ annotation_rows = (
+ ('bits', 'Bits', (15, 17)),
+ ('fields', 'Fields', tuple(range(15)) + (18, 19, 20)),
+ ('warnings', 'Warnings', (16,)),
+ )
+
+ def __init__(self):
+ self.reset()
+
+ def reset(self):
+ self.samplerate = None
+ self.reset_variables()
+
+ def start(self):
+ self.out_ann = self.register(srd.OUTPUT_ANN)
+
+ def metadata(self, key, value):
+ if key == srd.SRD_CONF_SAMPLERATE:
+ bitrate = 1000000 * float(self.options['bitrate'])
+ self.samplerate = value
+ self.bit_width = float(self.samplerate) / bitrate
+ self.sample_point = (self.bit_width / 100.0) * self.sample_point_percent
+
+ # Generic helper for FlexRay bit annotations.
+ def putg(self, ss, es, data):
+ left, right = int(self.sample_point), int(self.bit_width - self.sample_point)
+ self.put(ss - left, es + right, self.out_ann, data)
+
+ # Single-FlexRay-bit annotation using the current samplenum.
+ def putx(self, data):
+ self.putg(self.samplenum, self.samplenum, data)
+
+ # Multi-FlexRay-bit annotation from self.ss_block to current samplenum.
+ def putb(self, data):
+ self.putg(self.ss_block, self.samplenum, data)
+
+ # Generic CRC algorithm for any bit size and any data length. Used for
+ # 11-bit header and 24-bit trailer. Not very efficient but at least it
+ # works for now.
+ #
+ # TODO:
+ # - use precalculated tables to increase performance.
+ # - Add support for reverse CRC calculations.
+
+ @staticmethod
+ def crc(data, data_len_bits, polynom, crc_len_bits, iv=0, xor=0):
+ reg = iv ^ xor
+
+ for i in range(data_len_bits - 1, -1, -1):
+ bit = ((reg >> (crc_len_bits - 1)) & 0x1) ^ ((data >> i) & 0x1)
+ reg <<= 1
+ if bit:
+ reg ^= polynom
+
+ mask = (1 << crc_len_bits) - 1
+ crc = reg & mask
+
+ return crc ^ xor
+
+ def reset_variables(self):
+ self.sample_point_percent = 50 # TODO: use vote based sampling
+ self.state = 'IDLE'
+ self.tss_start = self.tss_end = self.frame_type = self.dlc = None
+ self.rawbits = [] # All bits, including byte start sequence bits
+ self.bits = [] # Only actual FlexRay frame bits (no byte start sequence bits)
+ self.curbit = 0 # Current bit of FlexRay frame (bit 0 == FSS)
+ self.last_databit = 999 # Positive value that bitnum+x will never match
+ self.last_xmit_bit = 999 # Positive value that bitnum+x will never match
+ self.ss_block = None
+ self.ss_databytebits = []
+ self.end_of_frame = False
+ self.dynamic_frame = False
+ self.ss_bit0 = None
+ self.ss_bit1 = None
+ self.ss_bit2 = None
+
+ # Poor man's clock synchronization. Use signal edges which change to
+ # dominant state in rather simple ways. This naive approach is neither
+ # aware of the SYNC phase's width nor the specific location of the edge,
+ # but improves the decoder's reliability when the input signal's bitrate
+ # does not exactly match the nominal rate.
+ def dom_edge_seen(self, force=False):
+ self.dom_edge_snum = self.samplenum
+ self.dom_edge_bcount = self.curbit
+
+ # Determine the position of the next desired bit's sample point.
+ def get_sample_point(self, bitnum):
+ samplenum = self.dom_edge_snum
+ samplenum += self.bit_width * (bitnum - self.dom_edge_bcount)
+ samplenum += self.sample_point
+ return int(samplenum)
+
+ def is_bss_sequence(self):
+ # FlexRay uses NRZ encoding and adds a binary 10 sequence before each
+ # byte. After each 8 data bits, a BSS sequence is added but not after
+ # frame CRC.
+
+ if self.end_of_frame:
+ return False
+
+ if (len(self.rawbits) - 2) % 10 == 0:
+ return True
+ elif (len(self.rawbits) - 3) % 10 == 0:
+ return True
+
+ return False
+
+ def handle_bit(self, fr_rx):
+ self.rawbits.append(fr_rx)
+ self.bits.append(fr_rx)
+
+ # Get the index of the current FlexRay frame bit.
+ bitnum = len(self.bits) - 1
+
+ # If this is a byte start sequence remove it from self.bits and ignore it.
+ if self.is_bss_sequence():
+ self.bits.pop()
+
+ if bitnum > 1:
+ self.putx([15, [str(fr_rx)]])
+ else:
+ if len(self.rawbits) == 2:
+ self.ss_bit1 = self.samplenum
+ elif len(self.rawbits) == 3:
+ self.ss_bit2 = self.samplenum
+
+ self.curbit += 1 # Increase self.curbit (bitnum is not affected).
+ return
+ else:
+ if bitnum > 1:
+ self.putx([17, [str(fr_rx)]])
+
+ # Bit 0: Frame start sequence (FSS) bit
+ if bitnum == 0:
+ self.ss_bit0 = self.samplenum
+
+ # Bit 1: Start of header
+ elif bitnum == 1:
+ if self.rawbits[:3] == [1, 1, 0]:
+ self.put(self.tss_start, self.tss_end, self.out_ann,
+ [1, ['Transmission start sequence', 'TSS']])
+
+ self.putg(self.ss_bit0, self.ss_bit0, [17, [str(self.rawbits[:3][0])]])
+ self.putg(self.ss_bit0, self.ss_bit0, [2, ['FSS', 'Frame start sequence']])
+ self.putg(self.ss_bit1, self.ss_bit1, [15, [str(self.rawbits[:3][1])]])
+ self.putg(self.ss_bit2, self.ss_bit2, [15, [str(self.rawbits[:3][2])]])
+ self.putx([17, [str(fr_rx)]])
+ self.putx([3, ['Reserved bit: %d' % fr_rx, 'RB: %d' % fr_rx, 'RB']])
+ else:
+ self.put(self.tss_start, self.tss_end, self.out_ann,
+ [20, ['Collision avoidance symbol', 'CAS']])
+ self.reset_variables()
+
+ # TODO: warning, if sequence is neither [1, 1, 0] nor [1, 1, 1]
+
+ # Bit 2: Payload preamble indicator. Must be 0 if null frame indicator is 0.
+ elif bitnum == 2:
+ self.putx([4, ['Payload preamble indicator: %d' % fr_rx,
+ 'PPI: %d' % fr_rx]])
+
+ # Bit 3: Null frame indicator (inversed)
+ elif bitnum == 3:
+ data_type = 'data frame' if fr_rx else 'null frame'
+ self.putx([5, ['Null frame indicator: %s' % data_type,
+ 'NF: %d' % fr_rx, 'NF']])
+
+ # Bit 4: Sync frame indicator
+ # Must be 1 if startup frame indicator is 1.
+ elif bitnum == 4:
+ self.putx([6, ['Sync frame indicator: %d' % fr_rx,
+ 'Sync: %d' % fr_rx, 'Sync']])
+
+ # Bit 5: Startup frame indicator
+ elif bitnum == 5:
+ self.putx([7, ['Startup frame indicator: %d' % fr_rx,
+ 'Startup: %d' % fr_rx, 'Startup']])
+
+ # Remember start of ID (see below).
+ elif bitnum == 6:
+ self.ss_block = self.samplenum
+
+ # Bits 6-16: Frame identifier (ID[10..0])
+ # ID must NOT be 0.
+ elif bitnum == 16:
+ self.id = int(''.join(str(d) for d in self.bits[6:]), 2)
+ self.putb([8, ['Frame ID: %d' % self.id, 'ID: %d' % self.id,
+ '%d' % self.id]])
+
+ # Remember start of payload length (see below).
+ elif bitnum == 17:
+ self.ss_block = self.samplenum
+
+ # Bits 17-23: Payload length (Length[7..0])
+ # Payload length in header is the half of the real payload size.
+ elif bitnum == 23:
+ self.payload_length = int(''.join(str(d) for d in self.bits[17:]), 2)
+ self.putb([9, ['Payload length: %d' % self.payload_length,
+ 'Length: %d' % self.payload_length,
+ '%d' % self.payload_length]])
+
+ # Remember start of header CRC (see below).
+ elif bitnum == 24:
+ self.ss_block = self.samplenum
+
+ # Bits 24-34: Header CRC (11-bit) (HCRC[11..0])
+ # Calculation of header CRC is equal on both channels.
+ elif bitnum == 34:
+ bits = ''.join([str(b) for b in self.bits[4:24]])
+ header_to_check = int(bits, 2)
+ expected_crc = self.crc(header_to_check, len(bits),
+ Const.cHCrcPolynomial, Const.cHCrcSize, Const.cHCrcInit)
+ self.header_crc = int(''.join(str(d) for d in self.bits[24:]), 2)
+
+ crc_ok = self.header_crc == expected_crc
+ crc_ann = "OK" if crc_ok else "bad"
+
+ self.putb([10, ['Header CRC: 0x%X (%s)' % (self.header_crc, crc_ann),
+ '0x%X (%s)' % (self.header_crc, crc_ann),
+ '0x%X' % self.header_crc]])
+
+ # Remember start of cycle code (see below).
+ elif bitnum == 35:
+ self.ss_block = self.samplenum
+
+ # Bits 35-40: Cycle code (Cyc[6..0])
+ # Cycle code. Must be between 0 and 63.
+ elif bitnum == 40:
+ self.cycle = int(''.join(str(d) for d in self.bits[35:]), 2)
+ self.putb([11, ['Cycle: %d' % self.cycle, 'Cyc: %d' % self.cycle,
+ '%d' % self.cycle]])
+ self.last_databit = 41 + 2 * self.payload_length * 8
+
+ # Remember all databyte bits, except the very last one.
+ elif bitnum in range(41, self.last_databit):
+ self.ss_databytebits.append(self.samplenum)
+
+ # Bits 41-X: Data field (0-254 bytes, depending on length)
+ # The bits within a data byte are transferred MSB-first.
+ elif bitnum == self.last_databit:
+ self.ss_databytebits.append(self.samplenum) # Last databyte bit.
+ for i in range(2 * self.payload_length):
+ x = 40 + (8 * i) + 1
+ b = int(''.join(str(d) for d in self.bits[x:x + 8]), 2)
+ ss = self.ss_databytebits[i * 8]
+ es = self.ss_databytebits[((i + 1) * 8) - 1]
+ self.putg(ss, es, [12, ['Data byte %d: 0x%02x' % (i, b),
+ 'DB%d: 0x%02x' % (i, b), '%02X' % b]])
+ self.ss_databytebits = []
+ self.ss_block = self.samplenum # Remember start of trailer CRC.
+
+ # Trailer CRC (24-bit) (CRC[11..0])
+ # Initialization vector of channel A and B are different, so CRCs are
+ # different for same data.
+ elif bitnum == self.last_databit + 23:
+ bits = ''.join([str(b) for b in self.bits[1:-24]])
+ frame_to_check = int(bits, 2)
+ iv = Const.cCrcInitA if self.options['channel_type'] == 'A' else Const.cCrcInitB
+ expected_crc = self.crc(frame_to_check, len(bits),
+ Const.cCrcPolynomial, Const.cCrcSize, iv=iv)
+ self.frame_crc = int(''.join(str(d) for d in self.bits[self.last_databit:]), 2)
+
+ crc_ok = self.frame_crc == expected_crc
+ crc_ann = "OK" if crc_ok else "bad"
+
+ self.putb([13, ['Frame CRC: 0x%X (%s)' % (self.frame_crc, crc_ann),
+ '0x%X (%s)' % (self.frame_crc, crc_ann),
+ '0x%X' % self.frame_crc]])
+ self.end_of_frame = True
+
+ # Remember start of frame end sequence (see below).
+ elif bitnum == self.last_databit + 24:
+ self.ss_block = self.samplenum
+
+ # Frame end sequence, must be 1 followed by 0.
+ elif bitnum == self.last_databit + 25:
+ self.putb([14, ['Frame end sequence', 'FES']])
+
+ # Check for DTS
+ elif bitnum == self.last_databit + 26:
+ if not fr_rx:
+ self.dynamic_frame = True
+ else:
+ self.last_xmit_bit = bitnum
+ self.ss_block = self.samplenum
+
+ # Remember start of channel idle delimiter (see below).
+ elif bitnum == self.last_xmit_bit:
+ self.ss_block = self.samplenum
+
+ # Channel idle limiter (CID[11..0])
+ elif bitnum == self.last_xmit_bit + Const.cChannelIdleDelimiter - 1:
+ self.putb([18, ['Channel idle delimiter', 'CID']])
+ self.reset_variables()
+
+ # DTS if dynamic frame
+ elif bitnum > self.last_databit + 27:
+ if self.dynamic_frame:
+ if fr_rx:
+ if self.last_xmit_bit == 999:
+ self.putb([19, ['Dynamic trailing sequence', 'DTS']])
+ self.last_xmit_bit = bitnum + 1
+ self.ss_block = self.samplenum
+
+ self.curbit += 1
+
+ def decode(self):
+ if not self.samplerate:
+ raise SamplerateError('Cannot decode without samplerate.')
+
+ while True:
+ # State machine.
+ if self.state == 'IDLE':
+ # Wait for a dominant state (logic 0) on the bus.
+ (fr_rx,) = self.wait({0: 'l'})
+ self.tss_start = self.samplenum
+ (fr_rx,) = self.wait({0: 'h'})
+ self.tss_end = self.samplenum
+ self.dom_edge_seen(force = True)
+ self.state = 'GET BITS'
+ elif self.state == 'GET BITS':
+ # Wait until we're in the correct bit/sampling position.
+ pos = self.get_sample_point(self.curbit)
+ (fr_rx,) = self.wait([{'skip': pos - self.samplenum}, {0: 'f'}])
+ if self.matched[1]:
+ self.dom_edge_seen()
+ if self.matched[0]:
+ self.handle_bit(fr_rx)
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