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120 lines
4.1 KiB
Python
Executable File
120 lines
4.1 KiB
Python
Executable File
##
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## This file is part of the libsigrokdecode project.
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##
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## Copyright (C) 2018 fenugrec <fenugrec@users.sourceforge.net>
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## Copyright (C) 2019 DreamSourceLab <support@dreamsourcelab.com>
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##
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## This program is free software; you can redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation; either version 2 of the License, or
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## (at your option) any later version.
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##
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License
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## along with this program; if not, see <http://www.gnu.org/licenses/>.
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##
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import sigrokdecode as srd
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class ChannelError(Exception):
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pass
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class Decoder(srd.Decoder):
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api_version = 3
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id = 'mcs48'
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name = 'MCS-48'
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longname = 'Intel MCS-48'
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desc = 'Intel MCS-48 external memory access protocol.'
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license = 'gplv2+'
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inputs = ['logic']
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outputs = []
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tags = ['Retro computing']
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channels = (
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{'id': 'ale', 'name': 'ALE', 'desc': 'Address latch enable'},
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{'id': 'psen', 'name': '/PSEN', 'desc': 'Program store enable'},
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) + tuple({
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'id': 'd%d' % i,
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'name': 'D%d' % i,
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'desc': 'CPU data line %d' % i
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} for i in range(0, 8)
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) + tuple({
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'id': 'a%d' % i,
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'name': 'A%d' % i,
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'desc': 'CPU address line %d' % i
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} for i in range(8, 12)
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)
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optional_channels = tuple({
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'id': 'a%d' % i,
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'name': 'A%d' % i,
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'desc': 'CPU address line %d' % i
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} for i in range(12, 13)
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)
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annotations = (
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('romdata', 'Address:Data'),
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)
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binary = (
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('romdata', 'AAAA:DD'),
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)
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def __init__(self):
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self.reset()
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def reset(self):
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self.addr = 0
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self.addr_s = 0
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self.data = 0
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self.data_s = 0
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# Flag to make sure we get an ALE pulse first.
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self.started = 0
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def start(self):
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self.out_ann = self.register(srd.OUTPUT_ANN)
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self.out_bin = self.register(srd.OUTPUT_BINARY)
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def newaddr(self, addr, data):
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# Falling edge on ALE: reconstruct address.
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self.started = 1
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addr = sum([bit << i for i, bit in enumerate(addr)])
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addr <<= len(data)
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addr |= sum([bit << i for i, bit in enumerate(data)])
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self.addr = addr
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self.addr_s = self.samplenum
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def newdata(self, data):
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# Edge on PSEN: get data.
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data = sum([bit << i for i, bit in enumerate(data)])
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self.data = data
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self.data_s = self.samplenum
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if self.started:
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anntext = '{:04X}:{:02X}'.format(self.addr, self.data)
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self.put(self.addr_s, self.data_s, self.out_ann, [0, [anntext]])
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bindata = self.addr.to_bytes(2, byteorder='big')
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bindata += self.data.to_bytes(1, byteorder='big')
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self.put(self.addr_s, self.data_s, self.out_bin, [0, bindata])
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def decode(self):
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# Address bits above A11 are optional, and are considered to be A12+.
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# This logic needs more adjustment when more bank address pins are
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# to get supported. For now, having just A12 is considered sufficient.
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has_bank = self.has_channel(14)
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bank_pin_count = 1 if has_bank else 0
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# Sample address on the falling ALE edge.
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# Save data on falling edge of PSEN.
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while True:
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(ale, psen, d0, d1, d2, d3, d4, d5, d6, d7, a8, a9, a10, a11, a12) = self.wait([{0: 'f'}, {1: 'r'}])
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data = (d0, d1, d2, d3, d4, d5, d6, d7)
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addr = (a8, a9, a10, a11)
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bank = (a12, )
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if has_bank:
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addr += bank[:bank_pin_count]
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# Handle those conditions (one or more) that matched this time.
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if (self.matched & (0b1 << 0)):
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self.newaddr(addr, data)
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if (self.matched & (0b1 << 1)):
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self.newdata(data)
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