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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2018 fenugrec <fenugrec@users.sourceforge.net>
##
## 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/>.
##
# TODO: Make A12 optional; it's here because of an instrument (HP3478A) that
# drives a generic I/O pin to access 8kB of ROM; the MCS-48 only has a 4kB
# address space.
import sigrokdecode as srd
class ChannelError(Exception):
pass
class Decoder(srd.Decoder):
api_version = 3
id = 'mcs48'
name = 'MCS-48'
longname = 'Intel MCS-48'
desc = 'Intel MCS-48 external memory access protocol.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['mcs48']
channels = \
tuple({
'id': 'd%d' % i,
'name': 'D%d' % i,
'desc': 'CPU data line %d' % i
} for i in range(8)
) + tuple({
'id': 'a%d' % i,
'name': 'A%d' % i,
'desc': 'CPU address line %d' % i
} for i in range(8, 13)
) + (
{'id': 'ale', 'name': 'ALE', 'desc': 'Address latch enable'},
{'id': 'psen', 'name': '/PSEN', 'desc': 'Program store enable'},
)
annotations = (
('romdata', 'Address:Data'),
)
binary = (
('romdata', 'AAAA:DD'),
)
def __init__(self):
self.addr = 0
self.addr_s = 0
self.data = 0
self.data_s = 0
# Flag to make sure we get an ALE pulse first.
self.started = 0
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
self.out_bin = self.register(srd.OUTPUT_BINARY)
def newaddr(self, pins):
# Falling edge on ALE: reconstruct address.
self.started = 1
tempaddr = 0
for i in range(13):
tempaddr |= pins[i] << i
self.addr = tempaddr
self.addr_s = self.samplenum
def newdata(self, pins):
# Edge on PSEN: get data.
tempdata = 0
for i in range(8):
tempdata |= pins[i] << i
self.data = tempdata
self.data_s = self.samplenum
if self.started:
self.put(self.addr_s, self.samplenum, self.out_ann,
[0, ['%04X:' % self.addr + '%02X' % self.data]])
self.put(self.addr_s, self.samplenum, self.out_bin,
[0, bytes([(self.addr >> 8) & 0xFF, self.addr & 0xFF, self.data])])
def decode(self):
# Sample address on the falling ALE edge.
# Save data on falling edge of PSEN.
while True:
pins = self.wait([{13: 'f'}, {14: 'r'}])
# Handle those conditions (one or more) that matched this time.
if self.matched[0]:
self.newaddr(pins[0:])
if self.matched[1]:
self.newdata(pins[0:])
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