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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2017 Marcus Comstedt <marcus@mc.pp.se>
##
## 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
ann = [
['Size', 'L'],
['SrcAP', 'S'],
['DstAP', 'D'],
['Cmd', 'C'],
['Data'],
['Cksum', 'K'],
]
class Decoder(srd.Decoder):
api_version = 3
id = 'maple_bus'
name = 'Maple bus'
longname = 'SEGA Maple bus'
desc = 'Maple bus peripheral protocol for SEGA Dreamcast.'
license = 'gplv2+'
inputs = ['logic']
outputs = []
tags = ['Retro computing']
channels = (
{'id': 'sdcka', 'name': 'SDCKA', 'desc': 'Data/clock line A'},
{'id': 'sdckb', 'name': 'SDCKB', 'desc': 'Data/clock line B'},
)
annotations = (
('start', 'Start pattern'),
('end', 'End pattern'),
('start-with-crc', 'Start pattern with CRC'),
('occupancy', 'SDCKB occupancy pattern'),
('reset', 'RESET pattern'),
('bit', 'Bit'),
('size', 'Data size'),
('source', 'Source AP'),
('dest', 'Destination AP'),
('command', 'Command'),
('data', 'Data'),
('checksum', 'Checksum'),
('frame-error', 'Frame error'),
('checksum-error', 'Checksum error'),
('size-error', 'Size error'),
)
annotation_rows = (
('bits', 'Bits', (0, 1, 2, 3, 4, 5)),
('fields', 'Fields', (6, 7, 8, 9, 10, 11)),
('warnings', 'Warnings', (12, 13, 14)),
)
binary = (
('size', 'Data size'),
('source', 'Source AP'),
('dest', 'Destination AP'),
('command', 'Command code'),
('data', 'Data'),
('checksum', 'Checksum'),
)
def __init__(self):
self.reset()
def reset(self):
pass
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
self.out_binary = self.register(srd.OUTPUT_BINARY)
self.pending_bit_pos = None
def putx(self, data):
self.put(self.ss, self.es, self.out_ann, data)
def putb(self, data):
self.put(self.ss, self.es, self.out_binary, data)
def byte_annotation(self, bintype, d):
return [bintype + 6,
['%s: %02X' % (name, d) for name in ann[bintype]] + ['%02X' % d]]
def got_start(self):
self.putx([0, ['Start pattern', 'Start', 'S']])
def got_end(self):
self.putx([1, ['End pattern', 'End', 'E']])
if self.length != self.expected_length + 1:
self.putx([14, ['Size error', 'L error', 'LE']])
def got_start_with_crc(self):
self.putx([2, ['Start pattern with CRC', 'Start CRC', 'SC']])
def got_occupancy(self):
self.putx([3, ['SDCKB occupancy pattern', 'Occupancy', 'O']])
def got_reset(self):
self.putx([4, ['RESET pattern', 'RESET', 'R']])
def output_pending_bit(self):
if self.pending_bit_pos:
self.put(self.pending_bit_pos, self.pending_bit_pos, self.out_ann, [5, ['Bit: %d' % self.pending_bit, '%d' % self.pending_bit]])
def got_bit(self, n):
self.output_pending_bit()
self.data = self.data * 2 + n
self.pending_bit = n
self.pending_bit_pos = self.samplenum
def got_byte(self):
self.output_pending_bit()
bintype = 4
if self.length < 4:
if self.length == 0:
self.expected_length = 4 * (self.data + 1)
bintype = self.length
elif self.length == self.expected_length:
bintype = 5
if self.data != self.checksum:
self.putx([13, ['Cksum error', 'K error', 'KE']])
self.length = self.length + 1
self.checksum = self.checksum ^ self.data
self.putx(self.byte_annotation(bintype, self.data))
self.putb([bintype, bytes([self.data])])
self.pending_bit_pos = None
def frame_error(self):
self.putx([7, ['Frame error', 'F error', 'FE']])
def handle_start(self):
self.wait({0: 'l', 1: 'h'})
self.ss = self.samplenum
count = 0
while True:
sdcka, sdckb = self.wait([{1: 'f'}, {0: 'r'}])
if self.matched[0]:
count = count + 1
if self.matched[1]:
self.es = self.samplenum
if sdckb == 1:
if count == 4:
self.got_start()
return True
elif count == 6:
self.got_start_with_crc()
return True
elif count == 8:
self.got_occupancy()
return False
elif count >= 14:
self.got_reset()
return False
self.frame_error()
return False
def handle_byte_or_stop(self):
self.ss = self.samplenum
self.pending_bit_pos = None
initial = True
counta = 0
countb = 0
self.data = 0
while countb < 4:
sdcka, sdckb = self.wait([{0: 'f'}, {1: 'f'}])
self.es = self.samplenum
if self.matched[0]:
if counta == countb:
self.got_bit(sdckb)
counta = counta + 1
elif counta == 1 and countb == 0 and self.data == 0 and sdckb == 0:
self.wait([{0: 'h', 1: 'h'}, {0: 'f'}, {1: 'f'}])
self.es = self.samplenum
if self.matched[0]:
self.got_end()
else:
self.frame_error()
return False
else:
self.frame_error()
return False
elif self.matched[1]:
if counta == countb + 1:
self.got_bit(sdcka)
countb = countb + 1
elif counta == 0 and countb == 0 and sdcka == 1 and initial:
self.ss = self.samplenum
initial = False
else:
self.frame_error()
return False
self.wait({0: 'h'})
self.es = self.samplenum
self.got_byte()
return True
def decode(self):
while True:
while not self.handle_start():
pass
self.length = 0
self.expected_length = 4
self.checksum = 0
while self.handle_byte_or_stop():
pass
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