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 Decoder(srd.Decoder):
26 longname = 'Wiegand interface'
27 desc = 'Wiegand interface for electronic entry systems.'
32 {'id': 'd0', 'name': 'D0', 'desc': 'Data 0 line'},
33 {'id': 'd1', 'name': 'D1', 'desc': 'Data 1 line'},
36 {'id': 'active', 'desc': 'Data lines active level',
37 'default': 'low', 'values': ('low', 'high')},
38 {'id': 'bitwidth_ms', 'desc': 'Single bit width in milliseconds',
39 'default': 4, 'values': (1, 2, 4, 8, 16, 32)},
46 ('bits', 'Binary value', (0,)),
47 ('state', 'Stream state', (1,)),
51 self._samples_per_bit = 10
65 'Register output types and verify user supplied decoder values.'
66 self.out_ann = self.register(srd.OUTPUT_ANN)
67 self._active = self.options['active'] == 'high' and 1 or 0
68 self._inactive = 1 - self._active
70 def metadata(self, key, value):
71 'Receive decoder metadata about the data stream.'
72 if key == srd.SRD_CONF_SAMPLERATE:
73 ms_per_sample = 1000 * (1.0 / value)
74 ms_per_bit = float(self.options['bitwidth_ms'])
75 self._samples_per_bit = int(max(1, int(ms_per_bit / ms_per_sample)))
77 def _update_state(self, state, bit=None):
78 'Update state and bit values when they change.'
79 if self._bit is not None:
80 self._bits.append(self._bit)
81 self.put(self.ss_bit, self.samplenum, self.out_ann,
82 [0, [str(self._bit)]])
84 self.ss_bit = self.samplenum
86 # Set a timeout so that the final bit ends.
87 self.es_bit = self.samplenum + self._samples_per_bit
91 if state != self._state:
93 if self._state == 'data':
94 accum_bits = ''.join(str(x) for x in self._bits)
95 ann = [1, ['%d bits %s' % (len(self._bits), accum_bits),
96 '%d bits' % len(self._bits)]]
97 elif self._state == 'invalid':
98 ann = [1, [self._state]]
100 self.put(self.ss_state, self.samplenum, self.out_ann, ann)
101 self.ss_state = self.samplenum
105 def decode(self, ss, es, data):
106 for self.samplenum, (d0, d1) in data:
107 if d0 == self._d0_prev and d1 == self._d1_prev:
108 if self.es_bit and self.samplenum >= self.es_bit:
109 if (d0, d1) == (self._inactive, self._inactive):
110 self._update_state('idle')
112 self._update_state('invalid')
115 if self._state in (None, 'idle', 'data'):
116 if (d0, d1) == (self._active, self._inactive):
117 self._update_state('data', 0)
118 elif (d0, d1) == (self._inactive, self._active):
119 self._update_state('data', 1)
120 elif (d0, d1) == (self._active, self._active):
121 self._update_state('invalid')
122 elif self._state == 'invalid':
123 # Wait until we see an idle state before leaving invalid.
124 # This prevents inverted lines from being misread.
125 if (d0, d1) == (self._inactive, self._inactive):
126 self._update_state('idle')
128 self._d0_prev, self._d1_prev = d0, d1
131 return '%s: %s D0 %d D1 %d (active on %d), %d samples per bit' % (
132 self.name, self._state, self._d0_prev, self._d1_prev,
133 self._active, self._samples_per_bit)