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56c93143 UH |
1 | ## |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2013 Uwe Hermann <uwe@hermann-uwe.de> | |
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, write to the Free Software | |
18 | ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | ## | |
20 | ||
56c93143 UH |
21 | import sigrokdecode as srd |
22 | ||
23 | class Decoder(srd.Decoder): | |
12851357 | 24 | api_version = 2 |
56c93143 UH |
25 | id = 'guess_bitrate' |
26 | name = 'Guess bitrate' | |
27 | longname = 'Guess bitrate/baudrate' | |
28 | desc = 'Guess the bitrate/baudrate of a UART (or other) protocol.' | |
29 | license = 'gplv2+' | |
30 | inputs = ['logic'] | |
31 | outputs = ['guess_bitrate'] | |
6a15597a | 32 | channels = ( |
56c93143 | 33 | {'id': 'data', 'name': 'Data', 'desc': 'Data line'}, |
da9bcbd9 BV |
34 | ) |
35 | annotations = ( | |
36 | ('bitrate', 'Bitrate / baudrate'), | |
37 | ) | |
56c93143 UH |
38 | |
39 | def putx(self, data): | |
40 | self.put(self.ss_edge, self.samplenum, self.out_ann, data) | |
41 | ||
42 | def __init__(self, **kwargs): | |
43 | self.olddata = None | |
44 | self.ss_edge = None | |
45 | self.first_transition = True | |
46 | self.bitwidth = None | |
47 | ||
e2ff870e | 48 | def start(self): |
be465111 | 49 | self.out_ann = self.register(srd.OUTPUT_ANN) |
56c93143 | 50 | |
e2ff870e UH |
51 | def metadata(self, key, value): |
52 | if key == srd.SRD_CONF_SAMPLERATE: | |
53 | self.samplerate = value; | |
54 | ||
56c93143 | 55 | def decode(self, ss, es, data): |
e2ff870e UH |
56 | if self.samplerate is None: |
57 | raise Exception("Cannot decode without samplerate.") | |
56c93143 UH |
58 | for (self.samplenum, pins) in data: |
59 | ||
60 | data = pins[0] | |
61 | ||
62 | # Wait for any transition on the data line. | |
63 | if data == self.olddata: | |
64 | continue | |
65 | ||
66 | # Initialize first self.olddata with the first sample value. | |
67 | if self.olddata == None: | |
68 | self.olddata = data | |
69 | continue | |
70 | ||
71 | # Get the smallest distance between two transitions | |
72 | # and use that to calculate the bitrate/baudrate. | |
73 | if self.first_transition == True: | |
74 | self.ss_edge = self.samplenum | |
75 | self.first_transition = False | |
76 | else: | |
77 | b = self.samplenum - self.ss_edge | |
78 | if self.bitwidth == None or b < self.bitwidth: | |
79 | self.bitwidth = b | |
80 | bitrate = int(float(self.samplerate) / float(b)) | |
81 | self.putx([0, ['%d' % bitrate]]) | |
82 | self.ss_edge = self.samplenum | |
83 | ||
84 | self.olddata = data | |
85 |