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1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2018 fenugrec <fenugrec@users.sourceforge.net> | |
5 | ## | |
6 | ## This program is free software; you can redistribute it and/or modify | |
7 | ## it under the terms of the GNU General Public License as published by | |
8 | ## the Free Software Foundation; either version 2 of the License, or | |
9 | ## (at your option) any later version. | |
10 | ## | |
11 | ## This program is distributed in the hope that it will be useful, | |
12 | ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ## GNU General Public License for more details. | |
15 | ## | |
16 | ## You should have received a copy of the GNU General Public License | |
17 | ## along with this program; if not, see <http://www.gnu.org/licenses/>. | |
18 | ## | |
19 | ||
20 | import sigrokdecode as srd | |
21 | ||
22 | class ChannelError(Exception): | |
23 | pass | |
24 | ||
25 | class Decoder(srd.Decoder): | |
26 | api_version = 3 | |
27 | id = 'mcs48' | |
28 | name = 'MCS-48' | |
29 | longname = 'Intel MCS-48' | |
30 | desc = 'Intel MCS-48 external memory access protocol.' | |
31 | license = 'gplv2+' | |
32 | inputs = ['logic'] | |
33 | outputs = ['mcs48'] | |
34 | tags = ['Retro computing'] | |
35 | channels = ( | |
36 | {'id': 'ale', 'name': 'ALE', 'desc': 'Address latch enable'}, | |
37 | {'id': 'psen', 'name': '/PSEN', 'desc': 'Program store enable'}, | |
38 | ) + tuple({ | |
39 | 'id': 'd%d' % i, | |
40 | 'name': 'D%d' % i, | |
41 | 'desc': 'CPU data line %d' % i | |
42 | } for i in range(0, 8) | |
43 | ) + tuple({ | |
44 | 'id': 'a%d' % i, | |
45 | 'name': 'A%d' % i, | |
46 | 'desc': 'CPU address line %d' % i | |
47 | } for i in range(8, 12) | |
48 | ) | |
49 | optional_channels = tuple({ | |
50 | 'id': 'a%d' % i, | |
51 | 'name': 'A%d' % i, | |
52 | 'desc': 'CPU address line %d' % i | |
53 | } for i in range(12, 13) | |
54 | ) | |
55 | annotations = ( | |
56 | ('romdata', 'Address:Data'), | |
57 | ) | |
58 | binary = ( | |
59 | ('romdata', 'AAAA:DD'), | |
60 | ) | |
61 | OFF_ALE, OFF_PSEN = 0, 1 | |
62 | OFF_DATA_BOT, OFF_DATA_TOP = 2, 10 | |
63 | OFF_ADDR_BOT, OFF_ADDR_TOP = 10, 14 | |
64 | OFF_BANK_BOT, OFF_BANK_TOP = 14, 15 | |
65 | ||
66 | def __init__(self): | |
67 | self.reset() | |
68 | ||
69 | def reset(self): | |
70 | self.addr = 0 | |
71 | self.addr_s = 0 | |
72 | self.data = 0 | |
73 | self.data_s = 0 | |
74 | ||
75 | # Flag to make sure we get an ALE pulse first. | |
76 | self.started = 0 | |
77 | ||
78 | def start(self): | |
79 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
80 | self.out_bin = self.register(srd.OUTPUT_BINARY) | |
81 | ||
82 | def newaddr(self, addr, data): | |
83 | # Falling edge on ALE: reconstruct address. | |
84 | self.started = 1 | |
85 | addr = sum([bit << i for i, bit in enumerate(addr)]) | |
86 | addr <<= len(data) | |
87 | addr |= sum([bit << i for i, bit in enumerate(data)]) | |
88 | self.addr = addr | |
89 | self.addr_s = self.samplenum | |
90 | ||
91 | def newdata(self, data): | |
92 | # Edge on PSEN: get data. | |
93 | data = sum([bit << i for i, bit in enumerate(data)]) | |
94 | self.data = data | |
95 | self.data_s = self.samplenum | |
96 | if self.started: | |
97 | anntext = '{:04X}:{:02X}'.format(self.addr, self.data) | |
98 | self.put(self.addr_s, self.data_s, self.out_ann, [0, [anntext]]) | |
99 | bindata = self.addr.to_bytes(2, byteorder='big') | |
100 | bindata += self.data.to_bytes(1, byteorder='big') | |
101 | self.put(self.addr_s, self.data_s, self.out_bin, [0, bindata]) | |
102 | ||
103 | def decode(self): | |
104 | # Address bits above A11 are optional, and are considered to be A12+. | |
105 | # This logic needs more adjustment when more bank address pins are | |
106 | # to get supported. For now, having just A12 is considered sufficient. | |
107 | has_bank = self.has_channel(self.OFF_BANK_BOT) | |
108 | bank_pin_count = 1 if has_bank else 0 | |
109 | # Sample address on the falling ALE edge. | |
110 | # Save data on falling edge of PSEN. | |
111 | while True: | |
112 | pins = self.wait([{self.OFF_ALE: 'f'}, {self.OFF_PSEN: 'r'}]) | |
113 | data = pins[self.OFF_DATA_BOT:self.OFF_DATA_TOP] | |
114 | addr = pins[self.OFF_ADDR_BOT:self.OFF_ADDR_TOP] | |
115 | bank = pins[self.OFF_BANK_BOT:self.OFF_BANK_TOP] | |
116 | if has_bank: | |
117 | addr += bank[:bank_pin_count] | |
118 | # Handle those conditions (one or more) that matched this time. | |
119 | if self.matched[0]: | |
120 | self.newaddr(addr, data) | |
121 | if self.matched[1]: | |
122 | self.newdata(data) |