/usr/share/libsigrokdecode/decoders/wiegand/pd.py is in libsigrokdecode4 0.5.0-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2016 Sean Burford <sburford@google.com>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, see <http://www.gnu.org/licenses/>.
##
import sigrokdecode as srd
class Decoder(srd.Decoder):
api_version = 2
id = 'wiegand'
name = 'Wiegand'
longname = 'Wiegand interface'
desc = 'Wiegand interface for electronic entry systems.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['wiegand']
channels = (
{'id': 'd0', 'name': 'D0', 'desc': 'Data 0 line'},
{'id': 'd1', 'name': 'D1', 'desc': 'Data 1 line'},
)
options = (
{'id': 'active', 'desc': 'Data lines active level',
'default': 'low', 'values': ('low', 'high')},
{'id': 'bitwidth_ms', 'desc': 'Single bit width in milliseconds',
'default': 4, 'values': (1, 2, 4, 8, 16, 32)},
)
annotations = (
('bits', 'Bits'),
('state', 'State'),
)
annotation_rows = (
('bits', 'Binary value', (0,)),
('state', 'Stream state', (1,)),
)
def __init__(self):
self._samples_per_bit = 10
self._d0_prev = None
self._d1_prev = None
self._state = None
self.ss_state = None
self.ss_bit = None
self.es_bit = None
self._bit = None
self._bits = []
def start(self):
'Register output types and verify user supplied decoder values.'
self.out_ann = self.register(srd.OUTPUT_ANN)
self._active = self.options['active'] == 'high' and 1 or 0
self._inactive = 1 - self._active
def metadata(self, key, value):
'Receive decoder metadata about the data stream.'
if key == srd.SRD_CONF_SAMPLERATE:
ms_per_sample = 1000 * (1.0 / value)
ms_per_bit = float(self.options['bitwidth_ms'])
self._samples_per_bit = int(max(1, int(ms_per_bit / ms_per_sample)))
def _update_state(self, state, bit=None):
'Update state and bit values when they change.'
if self._bit is not None:
self._bits.append(self._bit)
self.put(self.ss_bit, self.samplenum, self.out_ann,
[0, [str(self._bit)]])
self._bit = bit
self.ss_bit = self.samplenum
if bit is not None:
# Set a timeout so that the final bit ends.
self.es_bit = self.samplenum + self._samples_per_bit
else:
self.es_bit = None
if state != self._state:
ann = None
if self._state == 'data':
accum_bits = ''.join(str(x) for x in self._bits)
ann = [1, ['%d bits %s' % (len(self._bits), accum_bits),
'%d bits' % len(self._bits)]]
elif self._state == 'invalid':
ann = [1, [self._state]]
if ann:
self.put(self.ss_state, self.samplenum, self.out_ann, ann)
self.ss_state = self.samplenum
self._state = state
self._bits = []
def decode(self, ss, es, data):
for self.samplenum, (d0, d1) in data:
if d0 == self._d0_prev and d1 == self._d1_prev:
if self.es_bit and self.samplenum >= self.es_bit:
if (d0, d1) == (self._inactive, self._inactive):
self._update_state('idle')
else:
self._update_state('invalid')
continue
if self._state in (None, 'idle', 'data'):
if (d0, d1) == (self._active, self._inactive):
self._update_state('data', 0)
elif (d0, d1) == (self._inactive, self._active):
self._update_state('data', 1)
elif (d0, d1) == (self._active, self._active):
self._update_state('invalid')
elif self._state == 'invalid':
# Wait until we see an idle state before leaving invalid.
# This prevents inverted lines from being misread.
if (d0, d1) == (self._inactive, self._inactive):
self._update_state('idle')
self._d0_prev, self._d1_prev = d0, d1
def report(self):
return '%s: %s D0 %d D1 %d (active on %d), %d samples per bit' % (
self.name, self._state, self._d0_prev, self._d1_prev,
self._active, self._samples_per_bit)
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