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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2013 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
##
import sigrokdecode as srd
'''
OUTPUT_PYTHON format:
Packet:
[<ptype>, <pdata>]
<ptype>, <pdata>
- 'ITEM', [<item>, <itembitsize>]
- 'WORD', [<word>, <wordbitsize>, <worditemcount>]
<item>:
- A single item (a number). It can be of arbitrary size. The max. number
of bits in this item is specified in <itembitsize>.
<itembitsize>:
- The size of an item (in bits). For a 4-bit parallel bus this is 4,
for a 16-bit parallel bus this is 16, and so on.
<word>:
- A single word (a number). It can be of arbitrary size. The max. number
of bits in this word is specified in <wordbitsize>. The (exact) number
of items in this word is specified in <worditemcount>.
<wordbitsize>:
- The size of a word (in bits). For a 2-item word with 8-bit items
<wordbitsize> is 16, for a 3-item word with 4-bit items <wordbitsize>
is 12, and so on.
<worditemcount>:
- The size of a word (in number of items). For a 4-item word (no matter
how many bits each item consists of) <worditemcount> is 4, for a 7-item
word <worditemcount> is 7, and so on.
'''
def channel_list(num_channels):
l = [{'id': 'clk', 'name': 'CLK', 'desc': 'Clock line'}]
for i in range(num_channels):
d = {'id': 'd%d' % i, 'name': 'D%d' % i, 'desc': 'Data line %d' % i}
l.append(d)
return tuple(l)
class Decoder(srd.Decoder):
api_version = 1
id = 'parallel'
name = 'Parallel'
longname = 'Parallel sync bus'
desc = 'Generic parallel synchronous bus.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['parallel']
optional_channels = channel_list(8)
options = (
{'id': 'clock_edge', 'desc': 'Clock edge to sample on',
'default': 'rising', 'values': ('rising', 'falling')},
{'id': 'wordsize', 'desc': 'Data wordsize', 'default': 1},
{'id': 'endianness', 'desc': 'Data endianness',
'default': 'little', 'values': ('little', 'big')},
)
annotations = (
('items', 'Items'),
('words', 'Words'),
)
def __init__(self):
self.oldclk = None
self.items = []
self.itemcount = 0
self.saved_item = None
self.samplenum = 0
self.oldpins = None
self.ss_item = self.es_item = None
self.first = True
self.state = 'IDLE'
def start(self):
self.out_python = self.register(srd.OUTPUT_PYTHON)
self.out_ann = self.register(srd.OUTPUT_ANN)
def putpb(self, data):
self.put(self.ss_item, self.es_item, self.out_python, data)
def putb(self, data):
self.put(self.ss_item, self.es_item, self.out_ann, data)
def putpw(self, data):
self.put(self.ss_word, self.es_word, self.out_python, data)
def putw(self, data):
self.put(self.ss_word, self.es_word, self.out_ann, data)
def handle_bits(self, datapins):
# If this is the first item in a word, save its sample number.
if self.itemcount == 0:
self.ss_word = self.samplenum
# Get the bits for this item.
item, used_pins = 0, datapins.count(b'\x01') + datapins.count(b'\x00')
for i in range(used_pins):
item |= datapins[i] << i
self.items.append(item)
self.itemcount += 1
if self.first == True:
# Save the start sample and item for later (no output yet).
self.ss_item = self.samplenum
self.first = False
self.saved_item = item
else:
# Output the saved item (from the last CLK edge to the current).
self.es_item = self.samplenum
self.putpb(['ITEM', self.saved_item])
self.putb([0, ['%X' % self.saved_item]])
self.ss_item = self.samplenum
self.saved_item = item
endian, ws = self.options['endianness'], self.options['wordsize']
# Get as many items as the configured wordsize says.
if self.itemcount < ws:
return
# Output annotations/python for a word (a collection of items).
word = 0
for i in range(ws):
if endian == 'little':
word |= self.items[i] << ((ws - 1 - i) * used_pins)
elif endian == 'big':
word |= self.items[i] << (i * used_pins)
self.es_word = self.samplenum
# self.putpw(['WORD', word])
# self.putw([1, ['%X' % word]])
self.ss_word = self.samplenum
self.itemcount, self.items = 0, []
def find_clk_edge(self, clk, datapins):
# Ignore sample if the clock pin hasn't changed.
if clk == self.oldclk:
return
self.oldclk = clk
# Sample data on rising/falling clock edge (depends on config).
c = self.options['clock_edge']
if c == 'rising' and clk == 0: # Sample on rising clock edge.
return
elif c == 'falling' and clk == 1: # Sample on falling clock edge.
return
# Found the correct clock edge, now get the bits.
self.handle_bits(datapins)
def decode(self, ss, es, data):
for (self.samplenum, pins) in data:
# Ignore identical samples early on (for performance reasons).
if self.oldpins == pins:
continue
self.oldpins = pins
# State machine.
if self.state == 'IDLE':
if pins[0] not in (0, 1):
self.handle_bits(pins[1:])
else:
self.find_clk_edge(pins[0], pins[1:])
else:
raise Exception('Invalid state: %s' % self.state)
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