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61c2bd36 BV |
1 | ## |
2 | ## This file is part of the sigrok project. | |
3 | ## | |
4 | ## Copyright (C) 2012 Bert Vermeulen <bert@biot.com> | |
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 3 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 | ||
156509ca | 20 | # Generic I2C filtering protocol decoder |
61c2bd36 | 21 | |
156509ca | 22 | import sigrokdecode as srd |
61c2bd36 BV |
23 | |
24 | class Decoder(srd.Decoder): | |
25 | api_version = 1 | |
26 | id = 'i2cfilter' | |
27 | name = 'I2C filter' | |
28 | longname = 'I2C filter' | |
29 | desc = 'Filter out specific addresses/directions in an I2C stream.' | |
30 | license = 'gplv3+' | |
31 | inputs = ['i2c'] | |
32 | outputs = [] | |
33 | options = { | |
34 | 'address': ['Address to filter out of the I2C stream', 0], | |
35 | 'direction': ['Direction to filter (read/write)', ''] | |
36 | } | |
37 | ||
38 | def __init__(self, **kwargs): | |
39 | self.state = None | |
40 | ||
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'") | |
45 | ||
46 | def decode(self, ss, es, data): | |
47 | try: | |
48 | cmd, data, ack_bit = data | |
49 | except Exception as e: | |
50 | raise Exception('Malformed I2C input: %s' % str(e)) from e | |
51 | ||
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'): | |
55 | self.state = 'start' | |
56 | return | |
57 | if cmd == 'STOP': | |
58 | self.state = None | |
59 | return | |
60 | ||
61 | if self.state == 'start': | |
62 | # Start of a transfer, see if we want this one. | |
63 | if cmd == 'ADDRESS READ' and self.options['direction'] == 'write': | |
64 | return | |
65 | elif cmd == 'ADDRESS WRITE' and self.options['direction'] == 'read': | |
66 | return | |
67 | elif cmd in ('ADDRESS READ', 'ADDRESS WRITE'): | |
68 | if self.options['address'] in (0, data): | |
69 | # We want this tranfer. | |
70 | self.state = 'transfer' | |
71 | elif self.state == 'transfer': | |
72 | if cmd in ('DATA READ', 'DATA WRITE'): | |
73 | self.put(ss, es, self.out_proto, data) | |
74 | else: | |
75 | raise Exception('Invalid state: %s' % self.state) | |
76 | ||
77 |