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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
##
## 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 3 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/>.
##
# Generic I2C filtering protocol decoder
# TODO: Support for filtering out multiple slave/direction pairs?
import sigrokdecode as srd
class Decoder(srd.Decoder):
api_version = 1
id = 'i2cfilter'
name = 'I2C filter'
longname = 'I2C filter'
desc = 'Filter out addresses/directions in an I2C stream.'
license = 'gplv3+'
inputs = ['i2c']
outputs = ['i2c']
probes = []
optional_probes = []
options = {
'address': ['Address to filter out of the I2C stream', 0],
'direction': ['Direction to filter (read/write/both)', 'both']
}
annotations = []
def __init__(self, **kwargs):
self.state = None
self.curslave = -1
self.curdirection = None
self.packets = [] # Local cache of I2C packets
def start(self):
self.out_proto = self.add(srd.OUTPUT_PROTO, 'i2c')
if self.options['address'] not in range(0, 127 + 1):
raise Exception('Invalid slave (must be 0..127).')
if self.options['direction'] not in ('both', 'read', 'write'):
raise Exception('Invalid direction (valid: read/write/both).')
def report(self):
pass
# Grab I2C packets into a local cache, until an I2C STOP condition
# packet comes along. At some point before that STOP condition, there
# will have been an ADDRESS READ or ADDRESS WRITE which contains the
# I2C address of the slave that the master wants to talk to.
# If that slave shall be filtered, output the cache (all packets from
# START to STOP) as proto 'i2c', otherwise drop it.
def decode(self, ss, es, data):
cmd, databyte = data
# Add the I2C packet to our local cache.
self.packets.append([ss, es, data])
if cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
self.curslave = databyte
self.curdirection = cmd[8:].lower()
elif cmd in ('STOP', 'START REPEAT'):
# If this chunk was not for the correct slave, drop it.
if self.options['address'] == 0:
pass
elif self.curslave != self.options['address']:
self.packets = []
return
# If this chunk was not in the right direction, drop it.
if self.options['direction'] == 'both':
pass
elif self.options['direction'] != self.curdirection:
self.packets = []
return
# TODO: START->STOP chunks with both read and write (Repeat START)
# Otherwise, send out the whole chunk of I2C packets.
for p in self.packets:
self.put(p[0], p[1], self.out_proto, p[2])
self.packets = []
else:
pass # Do nothing, only add the I2C packet to our cache.
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