2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2016 Sean Burford <sburford@google.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 2 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 import sigrokdecode as srd
22 class SamplerateError(Exception):
25 class Decoder(srd.Decoder):
29 longname = 'Wiegand interface'
30 desc = 'Wiegand interface for electronic entry systems.'
35 {'id': 'd0', 'name': 'D0', 'desc': 'Data 0 line'},
36 {'id': 'd1', 'name': 'D1', 'desc': 'Data 1 line'},
39 {'id': 'active', 'desc': 'Data lines active level',
40 'default': 'low', 'values': ('low', 'high')},
41 {'id': 'bitwidth_ms', 'desc': 'Single bit width in milliseconds',
42 'default': 4, 'values': (1, 2, 4, 8, 16, 32)},
49 ('bits', 'Binary value', (0,)),
50 ('state', 'Stream state', (1,)),
57 self.samplerate = None
58 self._samples_per_bit = 10
72 'Register output types and verify user supplied decoder values.'
73 self.out_ann = self.register(srd.OUTPUT_ANN)
74 self._active = 1 if self.options['active'] == 'high' else 0
75 self._inactive = 1 - self._active
77 def metadata(self, key, value):
78 'Receive decoder metadata about the data stream.'
79 if key == srd.SRD_CONF_SAMPLERATE:
80 self.samplerate = value
82 ms_per_sample = 1000 * (1.0 / self.samplerate)
83 ms_per_bit = float(self.options['bitwidth_ms'])
84 self._samples_per_bit = int(max(1, int(ms_per_bit / ms_per_sample)))
86 def _update_state(self, state, bit=None):
87 'Update state and bit values when they change.'
88 if self._bit is not None:
89 self._bits.append(self._bit)
90 self.put(self.ss_bit, self.samplenum, self.out_ann,
91 [0, [str(self._bit)]])
93 self.ss_bit = self.samplenum
95 # Set a timeout so that the final bit ends.
96 self.es_bit = self.samplenum + self._samples_per_bit
100 if state != self._state:
102 if self._state == 'data':
103 accum_bits = ''.join(str(x) for x in self._bits)
104 ann = [1, ['%d bits %s' % (len(self._bits), accum_bits),
105 '%d bits' % len(self._bits)]]
106 elif self._state == 'invalid':
107 ann = [1, [self._state]]
109 self.put(self.ss_state, self.samplenum, self.out_ann, ann)
110 self.ss_state = self.samplenum
115 if not self.samplerate:
116 raise SamplerateError('Cannot decode without samplerate.')
118 # TODO: Come up with more appropriate self.wait() conditions.
119 (d0, d1) = self.wait()
121 if d0 == self._d0_prev and d1 == self._d1_prev:
122 if self.es_bit and self.samplenum >= self.es_bit:
123 if (d0, d1) == (self._inactive, self._inactive):
124 self._update_state('idle')
126 self._update_state('invalid')
129 if self._state in (None, 'idle', 'data'):
130 if (d0, d1) == (self._active, self._inactive):
131 self._update_state('data', 0)
132 elif (d0, d1) == (self._inactive, self._active):
133 self._update_state('data', 1)
134 elif (d0, d1) == (self._active, self._active):
135 self._update_state('invalid')
136 elif self._state == 'invalid':
137 # Wait until we see an idle state before leaving invalid.
138 # This prevents inverted lines from being misread.
139 if (d0, d1) == (self._inactive, self._inactive):
140 self._update_state('idle')
142 self._d0_prev, self._d1_prev = d0, d1
145 return '%s: %s D0 %d D1 %d (active on %d), %d samples per bit' % (
146 self.name, self._state, self._d0_prev, self._d1_prev,
147 self._active, self._samples_per_bit)