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1 | ## |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2018 Jorge Solla Rubiales <jorgesolla@gmail.com> | |
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 | from .protocoldata import * | |
22 | ||
23 | # Pulse types | |
24 | class Pulse: | |
25 | INVALID, START, ZERO, ONE = range(4) | |
26 | ||
27 | # Protocol stats | |
28 | class Stat: | |
29 | WAIT_START, GET_BITS, WAIT_EOM, WAIT_ACK = range(4) | |
30 | ||
31 | # Pulse times in milliseconds | |
32 | timing = { | |
33 | Pulse.START: { | |
34 | 'low': { 'min': 3.5, 'max': 3.9 }, | |
35 | 'total': { 'min': 4.3, 'max': 4.7 } | |
36 | }, | |
37 | Pulse.ZERO: { | |
38 | 'low': { 'min': 1.3, 'max': 1.7 }, | |
39 | 'total': { 'min': 2.05, 'max': 2.75 } | |
40 | }, | |
41 | Pulse.ONE: { | |
42 | 'low': { 'min': 0.4, 'max': 0.8 }, | |
43 | 'total': { 'min': 2.05, 'max': 2.75 } | |
44 | } | |
45 | } | |
46 | ||
47 | class ChannelError(Exception): | |
48 | pass | |
49 | ||
50 | class Decoder(srd.Decoder): | |
51 | api_version = 3 | |
52 | id = 'cec' | |
53 | name = 'CEC' | |
54 | longname = 'HDMI-CEC' | |
55 | desc = 'HDMI Consumer Electronics Control (CEC) protocol.' | |
56 | license = 'gplv2+' | |
57 | inputs = ['logic'] | |
58 | outputs = ['cec'] | |
59 | channels = ( | |
60 | {'id': 'cec', 'name': 'CEC', 'desc': 'CEC bus data'}, | |
61 | ) | |
62 | annotations = ( | |
63 | ('st', 'Start'), | |
64 | ('eom-0', 'End of message'), | |
65 | ('eom-1', 'Message continued'), | |
66 | ('nack', 'ACK not set'), | |
67 | ('ack', 'ACK set'), | |
68 | ('bits', 'Bits'), | |
69 | ('bytes', 'Bytes'), | |
70 | ('frames', 'Frames'), | |
71 | ('sections', 'Sections'), | |
72 | ('warnings', 'Warnings') | |
73 | ) | |
74 | annotation_rows = ( | |
75 | ('bits', 'Bits', (0, 1, 2, 3, 4, 5)), | |
76 | ('bytes', 'Bytes', (6,)), | |
77 | ('frames', 'Frames', (7,)), | |
78 | ('sections', 'Sections', (8,)), | |
79 | ('warnings', 'Warnings', (9,)) | |
80 | ) | |
81 | ||
82 | def __init__(self): | |
83 | self.reset() | |
84 | ||
85 | def precalculate(self): | |
86 | # Restrict max length of ACK/NACK labels to 2 BIT pulses. | |
87 | bit_time = timing[Pulse.ZERO]['total']['min'] | |
88 | bit_time = bit_time * 2 | |
89 | self.max_ack_len_samples = round((bit_time / 1000) * self.samplerate) | |
90 | ||
91 | def reset(self): | |
92 | self.stat = Stat.WAIT_START | |
93 | self.samplerate = None | |
94 | self.fall_start = None | |
95 | self.fall_end = None | |
96 | self.rise = None | |
97 | self.reset_frame_vars() | |
98 | ||
99 | def reset_frame_vars(self): | |
100 | self.eom = None | |
101 | self.bit_count = 0 | |
102 | self.byte_count = 0 | |
103 | self.byte = 0 | |
104 | self.byte_start = None | |
105 | self.frame_start = None | |
106 | self.frame_end = None | |
107 | self.is_nack = 0 | |
108 | self.cmd_bytes = [] | |
109 | ||
110 | def metadata(self, key, value): | |
111 | if key == srd.SRD_CONF_SAMPLERATE: | |
112 | self.samplerate = value | |
113 | self.precalculate() | |
114 | ||
115 | def set_stat(self, stat): | |
116 | self.stat = stat | |
117 | ||
118 | def handle_frame(self, is_nack): | |
119 | if self.fall_start is None or self.fall_end is None: | |
120 | return | |
121 | ||
122 | i = 0 | |
123 | str = '' | |
124 | while i < len(self.cmd_bytes): | |
125 | str += '{:02x}'.format(self.cmd_bytes[i]['val']) | |
126 | if i != (len(self.cmd_bytes) - 1): | |
127 | str += ':' | |
128 | i += 1 | |
129 | ||
130 | self.put(self.frame_start, self.frame_end, self.out_ann, [7, [str]]) | |
131 | ||
132 | i = 0 | |
133 | operands = 0 | |
134 | str = '' | |
135 | while i < len(self.cmd_bytes): | |
136 | if i == 0: # Parse header | |
137 | (src, dst) = decode_header(self.cmd_bytes[i]['val']) | |
138 | str = 'HDR: ' + src + ', ' + dst | |
139 | elif i == 1: # Parse opcode | |
140 | str += ' | OPC: ' + decode_opcode(self.cmd_bytes[i]['val']) | |
141 | else: # Parse operands | |
142 | if operands == 0: | |
143 | str += ' | OPS: ' | |
144 | operands += 1 | |
145 | str += '0x{:02x}'.format(self.cmd_bytes[i]['val']) | |
146 | if i != len(self.cmd_bytes) - 1: | |
147 | str += ', ' | |
148 | i += 1 | |
149 | ||
150 | # Header only commands are PINGS | |
151 | if i == 1: | |
152 | if self.eom: | |
153 | str += ' | OPC: PING' | |
154 | else: | |
155 | str += ' | OPC: NONE. Aborted cmd' | |
156 | ||
157 | # Add extra information (ack of the command from the destination) | |
158 | if is_nack: | |
159 | str += ' | R: NACK' | |
160 | else: | |
161 | str += ' | R: ACK' | |
162 | ||
163 | self.put(self.frame_start, self.frame_end, self.out_ann, [8, [str]]) | |
164 | ||
165 | def process(self): | |
166 | zero_time = ((self.rise - self.fall_start) / self.samplerate) * 1000.0 | |
167 | total_time = ((self.fall_end - self.fall_start) / self.samplerate) * 1000.0 | |
168 | pulse = Pulse.INVALID | |
169 | ||
170 | # VALIDATION: Identify pulse based on length of the low period | |
171 | for key in timing: | |
172 | if zero_time >= timing[key]['low']['min'] and zero_time <= timing[key]['low']['max']: | |
173 | pulse = key | |
174 | break | |
175 | ||
176 | # VALIDATION: Invalid pulse | |
177 | if pulse == Pulse.INVALID: | |
178 | self.set_stat(Stat.WAIT_START) | |
179 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Invalid pulse: Wrong timing']]) | |
180 | return | |
181 | ||
182 | # VALIDATION: If waiting for start, discard everything else | |
183 | if self.stat == Stat.WAIT_START and pulse != Pulse.START: | |
184 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Expected START: BIT found']]) | |
185 | return | |
186 | ||
187 | # VALIDATION: If waiting for ACK or EOM, only BIT pulses (0/1) are expected | |
188 | if (self.stat == Stat.WAIT_ACK or self.stat == Stat.WAIT_EOM) and pulse == Pulse.START: | |
189 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Expected BIT: START received)']]) | |
190 | self.set_stat(Stat.WAIT_START) | |
191 | ||
192 | # VALIDATION: ACK bit pulse remains high till the next frame (if any): Validate only min time of the low period | |
193 | if self.stat == Stat.WAIT_ACK and pulse != Pulse.START: | |
194 | if total_time < timing[pulse]['total']['min']: | |
195 | pulse = Pulse.INVALID | |
196 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['ACK pulse below minimun time']]) | |
197 | self.set_stat(Stat.WAIT_START) | |
198 | return | |
199 | ||
200 | # VALIDATION / PING FRAME DETECTION: Initiator doesn't sets the EOM = 1 but stops sending when ack doesn't arrive | |
201 | if self.stat == Stat.GET_BITS and pulse == Pulse.START: | |
202 | # Make sure we received a complete byte to consider it a valid ping | |
203 | if self.bit_count == 0: | |
204 | self.handle_frame(self.is_nack) | |
205 | else: | |
206 | self.put(self.frame_start, self.samplenum, self.out_ann, [9, ['ERROR: Incomplete byte received']]) | |
207 | ||
208 | # Set wait start so we receive next frame | |
209 | self.set_stat(Stat.WAIT_START) | |
210 | ||
211 | # VALIDATION: Check timing of the BIT (0/1) pulse in any other case (not waiting for ACK) | |
212 | if self.stat != Stat.WAIT_ACK and pulse != Pulse.START: | |
213 | if total_time < timing[pulse]['total']['min'] or total_time > timing[pulse]['total']['max']: | |
214 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Bit pulse exceeds total pulse timespan']]) | |
215 | pulse = Pulse.INVALID | |
216 | self.set_stat(Stat.WAIT_START) | |
217 | return | |
218 | ||
219 | if pulse == Pulse.ZERO: | |
220 | bit = 0 | |
221 | elif pulse == Pulse.ONE: | |
222 | bit = 1 | |
223 | ||
224 | # STATE: WAIT START | |
225 | if self.stat == Stat.WAIT_START: | |
226 | self.set_stat(Stat.GET_BITS) | |
227 | self.reset_frame_vars() | |
228 | self.put(self.fall_start, self.fall_end, self.out_ann, [0, ['ST']]) | |
229 | ||
230 | # STATE: GET BITS | |
231 | elif self.stat == Stat.GET_BITS: | |
232 | # Reset stats on first bit | |
233 | if self.bit_count == 0: | |
234 | self.byte_start = self.fall_start | |
235 | self.byte = 0 | |
236 | ||
237 | # If 1st byte of the datagram save its sample num | |
238 | if len(self.cmd_bytes) == 0: | |
239 | self.frame_start = self.fall_start | |
240 | ||
241 | self.byte += (bit << (7 - self.bit_count)) | |
242 | self.bit_count += 1 | |
243 | self.put(self.fall_start, self.fall_end, self.out_ann, [5, [str(bit)]]) | |
244 | ||
245 | if self.bit_count == 8: | |
246 | self.bit_count = 0 | |
247 | self.byte_count += 1 | |
248 | self.set_stat(Stat.WAIT_EOM) | |
249 | self.put(self.byte_start, self.samplenum, self.out_ann, [6, ['0x{:02x}'.format(self.byte)]]) | |
250 | self.cmd_bytes.append({'st': self.byte_start, 'ed': self.samplenum, 'val': self.byte}) | |
251 | ||
252 | # STATE: WAIT EOM | |
253 | elif self.stat == Stat.WAIT_EOM: | |
254 | self.eom = bit | |
255 | self.frame_end = self.fall_end | |
256 | ||
257 | if self.eom: | |
258 | self.put(self.fall_start, self.fall_end, self.out_ann, [2, ['EOM=Y']]) | |
259 | else: | |
260 | self.put(self.fall_start, self.fall_end, self.out_ann, [1, ['EOM=N']]) | |
261 | ||
262 | self.set_stat(Stat.WAIT_ACK) | |
263 | ||
264 | # STATE: WAIT ACK | |
265 | elif self.stat == Stat.WAIT_ACK: | |
266 | # If a frame with broadcast destination is being sent, the ACK is | |
267 | # inverted: a 0 is considered a NACK, therefore we invert the value | |
268 | # of the bit here, so we match the real meaning of it. | |
269 | if (self.cmd_bytes[0]['val'] & 0x0F) == 0x0F: | |
270 | bit = ~bit & 0x01 | |
271 | ||
272 | if (self.fall_end - self.fall_start) > self.max_ack_len_samples: | |
273 | ann_end = self.fall_start + self.max_ack_len_samples | |
274 | else: | |
275 | ann_end = self.fall_end | |
276 | ||
277 | if bit: | |
278 | # Any NACK detected in the frame is enough to consider the | |
279 | # whole frame NACK'd. | |
280 | self.is_nack = 1 | |
281 | self.put(self.fall_start, ann_end, self.out_ann, [3, ['NACK']]) | |
282 | else: | |
283 | self.put(self.fall_start, ann_end, self.out_ann, [4, ['ACK']]) | |
284 | ||
285 | # After ACK bit, wait for new datagram or continue reading current | |
286 | # one based on EOM value. | |
287 | if self.eom or self.is_nack: | |
288 | self.set_stat(Stat.WAIT_START) | |
289 | self.handle_frame(self.is_nack) | |
290 | else: | |
291 | self.set_stat(Stat.GET_BITS) | |
292 | ||
293 | def start(self): | |
294 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
295 | ||
296 | def decode(self): | |
297 | if not self.samplerate: | |
298 | raise SamplerateError('Cannot decode without samplerate.') | |
299 | ||
300 | # Wait for first falling edge. | |
301 | self.wait({0: 'f'}) | |
302 | self.fall_end = self.samplenum | |
303 | ||
304 | while True: | |
305 | self.wait({0: 'r'}) | |
306 | self.rise = self.samplenum | |
307 | ||
308 | if self.stat == Stat.WAIT_ACK: | |
309 | self.wait([{0: 'f'}, {'skip': self.max_ack_len_samples}]) | |
310 | else: | |
311 | self.wait([{0: 'f'}]) | |
312 | ||
313 | self.fall_start = self.fall_end | |
314 | self.fall_end = self.samplenum | |
315 | self.process() | |
316 | ||
317 | # If there was a timeout while waiting for ACK: RESYNC. | |
318 | # Note: This is an expected situation as no new falling edge will | |
319 | # happen until next frame is transmitted. | |
320 | if self.matched == (False, True): | |
321 | self.wait({0: 'f'}) | |
322 | self.fall_end = self.samplenum |