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##
## This file is part of the sigrok project.
##
## 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 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, write to the Free Software
## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
##
#
# Generic I2C demultiplexing protocol decoder
#
# Takes an I2C stream as input and outputs multiple I2C streams, each stream
# containing only I2C packets for one specific I2C slave.
#
import sigrokdecode as srd
class Decoder(srd.Decoder):
api_version = 1
id = 'i2cdemux'
name = 'I2C demux'
longname = 'Generic I2C demultiplexer'
desc = 'TODO.'
longdesc = 'TODO.'
license = 'gplv2+'
inputs = ['i2c']
outputs = [] # TODO: Only known at run-time.
probes = []
extra_probes = []
options = {}
annotations = []
def __init__(self, **kwargs):
self.packets = [] # Local cache of I2C packets
self.slaves = [] # List of known slave addresses
self.stream = -1 # Current output stream
self.streamcount = 0 # Number of created output streams
def start(self, metadata):
self.out_proto = []
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.
# We use this slave address to figure out which output stream should
# get the whole chunk of packets (from START to STOP).
def decode(self, ss, es, data):
cmd, databyte, ack = data
# Add the I2C packet to our local cache.
self.packets += [[ss, es, data]]
if cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
if databyte in self.slaves:
self.stream = self.slaves.index(databyte)
return
# We're never seen this slave, add a new stream.
self.slaves += [databyte]
self.out_proto += [self.add(srd.OUTPUT_PROTO,
'i2c-%s' % hex(databyte))]
self.stream = self.streamcount
self.streamcount += 1
elif cmd == 'STOP':
if self.stream == -1:
raise Exception('Invalid stream!') # FIXME?
# Send the whole chunk of I2C packets to the correct stream.
for p in self.packets:
self.put(p[0], p[1], self.out_proto[self.stream], p[2])
self.packets = []
self.stream = -1
else:
pass # Do nothing, only add the I2C packet to our cache.
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