2 ## This file is part of the sigrok project.
4 ## Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
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 3 of the License, or
9 ## (at your option) any later version.
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.
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/>.
20 # Generic I2C filtering protocol decoder
22 import sigrokdecode as srd
24 class Decoder(srd.Decoder):
28 longname = 'I2C filter'
29 desc = 'Filter out specific addresses/directions in an I2C stream.'
34 'address': ['Address to filter out of the I2C stream', 0],
35 'direction': ['Direction to filter (read/write)', '']
38 def __init__(self, **kwargs):
41 def start(self, metadata):
42 self.out_proto = self.add(srd.OUTPUT_PROTO, 'i2cdata')
43 if self.options['direction'] not in ('', 'read', 'write'):
44 raise Exception('Invalid direction: expected "read" or "write"')
46 def decode(self, ss, es, data):
49 except Exception as e:
50 raise Exception('Malformed I2C input: %s' % str(e)) from e
52 # Whichever state we're in, these always reset the state machine.
53 # This should make it easier to deal with corrupt data etc.
54 if cmd in ('START', 'START REPEAT'):
60 if cmd in ('ACK', 'NACK'):
61 # Don't care, we just want data.
64 if self.state == 'start':
65 # Start of a transfer, see if we want this one.
66 if cmd == 'ADDRESS READ' and self.options['direction'] == 'write':
68 elif cmd == 'ADDRESS WRITE' and self.options['direction'] == 'read':
70 elif cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
71 if self.options['address'] in (0, data):
72 # We want this tranfer.
73 self.state = 'transfer'
74 elif self.state == 'transfer':
75 if cmd in ('DATA READ', 'DATA WRITE'):
76 self.put(ss, es, self.out_proto, data)
78 raise Exception('Invalid state: %s' % self.state)