X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=decoders%2Fi2c%2Fpd.py;h=f31e33ef85fb38341cb631c82b3dd912dccf7f87;hb=HEAD;hp=d9061f5d12d1848f5d04b839769947b0226d1d7d;hpb=647aba6af7745c14961674c5feebf83fd18303a3;p=libsigrokdecode.git diff --git a/decoders/i2c/pd.py b/decoders/i2c/pd.py index d9061f5..2259b45 100644 --- a/decoders/i2c/pd.py +++ b/decoders/i2c/pd.py @@ -46,20 +46,24 @@ Packet: command. Slave addresses do not include bit 0 (the READ/WRITE indication bit). For example, a slave address field could be 0x51 (instead of 0xa2). For 'START', 'START REPEAT', 'STOP', 'ACK', and 'NACK' is None. +For 'BITS' is a sequence of tuples of bit values and their start and +stop positions, in LSB first order (although the I2C protocol is MSB first). ''' -# CMD: [annotation-type-index, long annotation, short annotation] +# Meaning of table items: +# command -> [annotation class, annotation text in order of decreasing length] proto = { - 'START': [0, 'Start', 'S'], - 'START REPEAT': [1, 'Start repeat', 'Sr'], - 'STOP': [2, 'Stop', 'P'], - 'ACK': [3, 'ACK', 'A'], - 'NACK': [4, 'NACK', 'N'], - 'BIT': [5, 'Bit', 'B'], - 'ADDRESS READ': [6, 'Address read', 'AR'], - 'ADDRESS WRITE': [7, 'Address write', 'AW'], - 'DATA READ': [8, 'Data read', 'DR'], - 'DATA WRITE': [9, 'Data write', 'DW'], + 'START': [0, 'Start', 'S'], + 'START REPEAT': [1, 'Start repeat', 'Sr'], + 'STOP': [2, 'Stop', 'P'], + 'ACK': [3, 'ACK', 'A'], + 'NACK': [4, 'NACK', 'N'], + 'BIT': [5, '{b:1d}'], + 'ADDRESS READ': [6, 'Address read: {b:02X}', 'AR: {b:02X}', '{b:02X}'], + 'ADDRESS WRITE': [7, 'Address write: {b:02X}', 'AW: {b:02X}', '{b:02X}'], + 'DATA READ': [8, 'Data read: {b:02X}', 'DR: {b:02X}', '{b:02X}'], + 'DATA WRITE': [9, 'Data write: {b:02X}', 'DW: {b:02X}', '{b:02X}'], + 'WARN': [10, '{text}'], } class Decoder(srd.Decoder): @@ -110,14 +114,15 @@ class Decoder(srd.Decoder): def reset(self): self.samplerate = None - self.ss = self.es = self.ss_byte = -1 self.is_write = None self.rem_addr_bytes = None + self.slave_addr_7 = None + self.slave_addr_10 = None self.is_repeat_start = False - self.state = 'FIND START' self.pdu_start = None self.pdu_bits = 0 self.data_bits = [] + self.bitwidth = 0 def metadata(self, key, value): if key == srd.SRD_CONF_SAMPLERATE: @@ -130,31 +135,50 @@ class Decoder(srd.Decoder): self.out_bitrate = self.register(srd.OUTPUT_META, meta=(int, 'Bitrate', 'Bitrate from Start bit to Stop bit')) - def putx(self, data): - self.put(self.ss, self.es, self.out_ann, data) + def putg(self, ss, es, cls, text): + self.put(ss, es, self.out_ann, [cls, text]) - def putp(self, data): - self.put(self.ss, self.es, self.out_python, data) + def putp(self, ss, es, data): + self.put(ss, es, self.out_python, data) - def putb(self, data): - self.put(self.ss, self.es, self.out_binary, data) + def putb(self, ss, es, data): + self.put(ss, es, self.out_binary, data) - def handle_start(self, pins): - self.ss, self.es = self.samplenum, self.samplenum - self.pdu_start = self.samplenum - self.pdu_bits = 0 - cmd = 'START REPEAT' if self.is_repeat_start else 'START' - self.putp([cmd, None]) - self.putx([proto[cmd][0], proto[cmd][1:]]) - self.state = 'FIND ADDRESS' + def _wants_start(self): + # Check whether START is required (to sync to the input stream). + return self.pdu_start is None + + def _collects_address(self): + # Check whether the transfer still is in the address phase (is + # still collecting address and r/w details, or has not started + # collecting it). + return self.rem_addr_bytes is None or self.rem_addr_bytes != 0 + + def _collects_byte(self): + # Check whether bits of a byte are being collected. Outside of + # the data byte, the bit is the ACK/NAK slot. + return self.data_bits is None or len(self.data_bits) < 8 + + def handle_start(self, ss, es): + if self.is_repeat_start: + cmd = 'START REPEAT' + else: + cmd = 'START' + self.pdu_start = ss + self.pdu_bits = 0 + self.putp(ss, es, [cmd, None]) + cls, texts = proto[cmd][0], proto[cmd][1:] + self.putg(ss, es, cls, texts) self.is_repeat_start = True self.is_write = None + self.slave_addr_7 = None + self.slave_addr_10 = None self.rem_addr_bytes = None self.data_bits.clear() + self.bitwidth = 0 # Gather 8 bits of data plus the ACK/NACK bit. - def handle_address_or_data(self, pins): - scl, sda = pins + def handle_address_or_data(self, ss, es, value): self.pdu_bits += 1 # Accumulate a byte's bits, including its start position. @@ -163,26 +187,28 @@ class Decoder(srd.Decoder): # the bit value gets sampled. Assume the start of the next bit # as the end sample number of the previous bit. Guess the last # bit's end sample number from the second last bit's width. - # (gsi: Shouldn't falling SCL be the end of the bit value?) # Keep the bits in receive order (MSB first) during accumulation. - if not self.data_bits: - self.ss_byte = self.samplenum + # (gsi: Strictly speaking falling SCL would be the end of the + # bit value's validity. That'd break compatibility though.) if self.data_bits: - self.data_bits[-1][2] = self.samplenum - self.data_bits.append([sda, self.samplenum, self.samplenum]) + self.data_bits[-1][2] = ss + self.data_bits.append([value, ss, es]) if len(self.data_bits) < 8: return self.bitwidth = self.data_bits[-2][2] - self.data_bits[-3][2] - self.data_bits[-1][2] += self.bitwidth + self.data_bits[-1][2] = self.data_bits[-1][1] + self.bitwidth # Get the byte value. Address and data are transmitted MSB-first. d = bitpack_msb(self.data_bits, 0) - if self.state == 'FIND ADDRESS': - # The READ/WRITE bit is only in the first address byte, not - # in data bytes. Address bit pattern 0b1111_0xxx means that - # this is a 10bit slave address, another byte follows. Get - # the R/W direction and the address bytes count from the - # first byte in the I2C transfer. + ss_byte, es_byte = self.data_bits[0][1], self.data_bits[-1][2] + + # Process the address bytes at the start of a transfer. The + # first byte will carry the R/W bit, and all of the 7bit address + # or part of a 10bit address. Bit pattern 0b11110xxx signals + # that another byte follows which carries the remaining bits of + # a 10bit slave address. + is_address = self._collects_address() + if is_address: addr_byte = d if self.rem_addr_bytes is None: if (addr_byte & 0xf8) == 0xf0: @@ -194,101 +220,125 @@ class Decoder(srd.Decoder): self.rem_addr_bytes = 1 self.slave_addr_7 = addr_byte >> 1 self.slave_addr_10 = None - is_seven = self.slave_addr_7 is not None + has_rw_bit = self.is_write is None if self.is_write is None: read_bit = bool(addr_byte & 1) - shift_seven = self.options['address_format'] == 'shifted' - if is_seven and shift_seven: - d = d >> 1 + if self.options['address_format'] == 'shifted': + d >>= 1 self.is_write = False if read_bit else True - else: + elif self.slave_addr_10 is not None: self.slave_addr_10 |= addr_byte - + else: + cls, texts = proto['WARN'][0], proto['WARN'][1:] + msg = 'Unhandled address byte' + texts = [t.format(text = msg) for t in texts] + self.putg(ss_byte, es_byte, cls, texts) + is_write = self.is_write + is_seven = self.slave_addr_7 is not None + + # Determine annotation classes depending on whether the byte is + # an address or payload data, and whether it's written or read. bin_class = -1 - if self.state == 'FIND ADDRESS' and self.is_write: + if is_address and is_write: cmd = 'ADDRESS WRITE' bin_class = 1 - elif self.state == 'FIND ADDRESS' and not self.is_write: + elif is_address and not is_write: cmd = 'ADDRESS READ' bin_class = 0 - elif self.state == 'FIND DATA' and self.is_write: + elif not is_address and is_write: cmd = 'DATA WRITE' bin_class = 3 - elif self.state == 'FIND DATA' and not self.is_write: + elif not is_address and not is_write: cmd = 'DATA READ' bin_class = 2 - self.ss, self.es = self.ss_byte, self.samplenum + self.bitwidth - # Reverse the list of bits to LSB first order before emitting # annotations and passing bits to upper layers. This may be # unexpected because the protocol is MSB first, but it keeps # backwards compatibility. - self.data_bits.reverse() - self.putp(['BITS', self.data_bits]) - self.putp([cmd, d]) - - self.putb([bin_class, bytes([d])]) - - for bit in self.data_bits: - self.put(bit[1], bit[2], self.out_ann, [5, ['%d' % bit[0]]]) - - if cmd.startswith('ADDRESS') and is_seven: - self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth + lsb_bits = self.data_bits[:] + lsb_bits.reverse() + self.putp(ss_byte, es_byte, ['BITS', lsb_bits]) + self.putp(ss_byte, es_byte, [cmd, d]) + + self.putb(ss_byte, es_byte, [bin_class, bytes([d])]) + + for bit_value, ss_bit, es_bit in lsb_bits: + cls, texts = proto['BIT'][0], proto['BIT'][1:] + texts = [t.format(b = bit_value) for t in texts] + self.putg(ss_bit, es_bit, cls, texts) + + if is_address and has_rw_bit: + # Assign the last bit's location to the R/W annotation. + # Adjust the address value's location to the left. + ss_bit, es_bit = self.data_bits[-1][1], self.data_bits[-1][2] + es_byte = self.data_bits[-2][2] + cls = proto[cmd][0] w = ['Write', 'Wr', 'W'] if self.is_write else ['Read', 'Rd', 'R'] - self.putx([proto[cmd][0], w]) - self.ss, self.es = self.ss_byte, self.samplenum - - self.putx([proto[cmd][0], ['%s: %02X' % (proto[cmd][1], d), - '%s: %02X' % (proto[cmd][2], d), '%02X' % d]]) - - # Done with this packet. - self.data_bits.clear() - self.state = 'FIND ACK' - - def get_ack(self, pins): - scl, sda = pins - self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth - cmd = 'NACK' if (sda == 1) else 'ACK' - self.putp([cmd, None]) - self.putx([proto[cmd][0], proto[cmd][1:]]) + self.putg(ss_bit, es_bit, cls, w) + + cls, texts = proto[cmd][0], proto[cmd][1:] + texts = [t.format(b = d) for t in texts] + self.putg(ss_byte, es_byte, cls, texts) + + def get_ack(self, ss, es, value): + ss_bit, es_bit = ss, es + cmd = 'ACK' if value == 0 else 'NACK' + self.putp(ss_bit, es_bit, [cmd, None]) + cls, texts = proto[cmd][0], proto[cmd][1:] + self.putg(ss_bit, es_bit, cls, texts) # Slave addresses can span one or two bytes, before data bytes # follow. There can be an arbitrary number of data bytes. Stick # with getting more address bytes if applicable, or enter or # remain in the data phase of the transfer otherwise. if self.rem_addr_bytes: self.rem_addr_bytes -= 1 - if self.rem_addr_bytes: - self.state = 'FIND ADDRESS' - else: - self.state = 'FIND DATA' + self.data_bits.clear() - def handle_stop(self, pins): + def handle_stop(self, ss, es): # Meta bitrate - if self.samplerate: - elapsed = 1 / float(self.samplerate) * (self.samplenum - self.pdu_start + 1) + if self.samplerate and self.pdu_start: + elapsed = es - self.pdu_start + 1 + elapsed /= self.samplerate bitrate = int(1 / elapsed * self.pdu_bits) - self.put(self.ss_byte, self.samplenum, self.out_bitrate, bitrate) + ss_meta, es_meta = self.pdu_start, es + self.put(ss_meta, es_meta, self.out_bitrate, bitrate) + self.pdu_start = None + self.pdu_bits = 0 cmd = 'STOP' - self.ss, self.es = self.samplenum, self.samplenum - self.putp([cmd, None]) - self.putx([proto[cmd][0], proto[cmd][1:]]) - self.state = 'FIND START' + self.putp(ss, es, [cmd, None]) + cls, texts = proto[cmd][0], proto[cmd][1:] + self.putg(ss, es, cls, texts) self.is_repeat_start = False self.is_write = None self.data_bits.clear() def decode(self): + # Check for several bus conditions. Determine sample numbers + # here and pass ss, es, and bit values to handling routines. while True: # State machine. - if self.state == 'FIND START': + # BEWARE! This implementation expects to see valid traffic, + # is rather picky in which phase which symbols get handled. + # This attempts to support severely undersampled captures, + # which a previous implementation happened to read instead + # of rejecting the inadequate input data. + # NOTE that handling bits at the start of their validity, + # and assuming that they remain valid until the next bit + # starts, is also done for backwards compatibility. + if self._wants_start(): # Wait for a START condition (S): SCL = high, SDA = falling. - self.handle_start(self.wait({0: 'h', 1: 'f'})) - elif self.state == 'FIND ADDRESS': + pins = self.wait({0: 'h', 1: 'f'}) + ss, es = self.samplenum, self.samplenum + self.handle_start(ss, es) + elif self._collects_address() and self._collects_byte(): # Wait for a data bit: SCL = rising. - self.handle_address_or_data(self.wait({0: 'r'})) - elif self.state == 'FIND DATA': + pins = self.wait({0: 'r'}) + _, sda = pins + ss, es = self.samplenum, self.samplenum + self.bitwidth + self.handle_address_or_data(ss, es, sda) + elif self._collects_byte(): # Wait for any of the following conditions (or combinations): # a) Data sampling of receiver: SCL = rising, and/or # b) START condition (S): SCL = high, SDA = falling, and/or @@ -297,11 +347,18 @@ class Decoder(srd.Decoder): # Check which of the condition(s) matched and handle them. if self.matched[0]: - self.handle_address_or_data(pins) + _, sda = pins + ss, es = self.samplenum, self.samplenum + self.bitwidth + self.handle_address_or_data(ss, es, sda) elif self.matched[1]: - self.handle_start(pins) + ss, es = self.samplenum, self.samplenum + self.handle_start(ss, es) elif self.matched[2]: - self.handle_stop(pins) - elif self.state == 'FIND ACK': + ss, es = self.samplenum, self.samplenum + self.handle_stop(ss, es) + else: # Wait for a data/ack bit: SCL = rising. - self.get_ack(self.wait({0: 'r'})) + pins = self.wait({0: 'r'}) + _, sda = pins + ss, es = self.samplenum, self.samplenum + self.bitwidth + self.get_ack(ss, es, sda)