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fb248c04 JS |
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'] | |
6cbba91f | 58 | outputs = [] |
d6d8a8a4 | 59 | tags = ['Display', 'PC'] |
fb248c04 JS |
60 | channels = ( |
61 | {'id': 'cec', 'name': 'CEC', 'desc': 'CEC bus data'}, | |
62 | ) | |
63 | annotations = ( | |
64 | ('st', 'Start'), | |
65 | ('eom-0', 'End of message'), | |
66 | ('eom-1', 'Message continued'), | |
67 | ('nack', 'ACK not set'), | |
68 | ('ack', 'ACK set'), | |
e144452b UH |
69 | ('bit', 'Bit'), |
70 | ('byte', 'Byte'), | |
71 | ('frame', 'Frame'), | |
72 | ('section', 'Section'), | |
73 | ('warning', 'Warning') | |
fb248c04 JS |
74 | ) |
75 | annotation_rows = ( | |
76 | ('bits', 'Bits', (0, 1, 2, 3, 4, 5)), | |
77 | ('bytes', 'Bytes', (6,)), | |
78 | ('frames', 'Frames', (7,)), | |
79 | ('sections', 'Sections', (8,)), | |
80 | ('warnings', 'Warnings', (9,)) | |
81 | ) | |
82 | ||
83 | def __init__(self): | |
84 | self.reset() | |
85 | ||
86 | def precalculate(self): | |
87 | # Restrict max length of ACK/NACK labels to 2 BIT pulses. | |
8a8b516a | 88 | bit_time = timing[Pulse.ZERO]['total']['min'] * 2 |
fb248c04 JS |
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 | ||
fb248c04 JS |
115 | def handle_frame(self, is_nack): |
116 | if self.fall_start is None or self.fall_end is None: | |
117 | return | |
118 | ||
119 | i = 0 | |
16d2031b | 120 | string = '' |
fb248c04 | 121 | while i < len(self.cmd_bytes): |
16d2031b | 122 | string += '{:02x}'.format(self.cmd_bytes[i]['val']) |
fb248c04 | 123 | if i != (len(self.cmd_bytes) - 1): |
16d2031b | 124 | string += ':' |
fb248c04 JS |
125 | i += 1 |
126 | ||
16d2031b | 127 | self.put(self.frame_start, self.frame_end, self.out_ann, [7, [string]]) |
fb248c04 JS |
128 | |
129 | i = 0 | |
130 | operands = 0 | |
16d2031b | 131 | string = '' |
fb248c04 JS |
132 | while i < len(self.cmd_bytes): |
133 | if i == 0: # Parse header | |
134 | (src, dst) = decode_header(self.cmd_bytes[i]['val']) | |
16d2031b | 135 | string = 'HDR: ' + src + ', ' + dst |
fb248c04 | 136 | elif i == 1: # Parse opcode |
16d2031b | 137 | string += ' | OPC: ' + opcodes.get(self.cmd_bytes[i]['val'], 'Invalid') |
fb248c04 JS |
138 | else: # Parse operands |
139 | if operands == 0: | |
16d2031b | 140 | string += ' | OPS: ' |
fb248c04 | 141 | operands += 1 |
16d2031b | 142 | string += '0x{:02x}'.format(self.cmd_bytes[i]['val']) |
fb248c04 | 143 | if i != len(self.cmd_bytes) - 1: |
16d2031b | 144 | string += ', ' |
fb248c04 JS |
145 | i += 1 |
146 | ||
147 | # Header only commands are PINGS | |
148 | if i == 1: | |
16d2031b | 149 | string += ' | OPC: PING' if self.eom else ' | OPC: NONE. Aborted cmd' |
fb248c04 JS |
150 | |
151 | # Add extra information (ack of the command from the destination) | |
16d2031b | 152 | string += ' | R: NACK' if is_nack else ' | R: ACK' |
fb248c04 | 153 | |
16d2031b | 154 | self.put(self.frame_start, self.frame_end, self.out_ann, [8, [string]]) |
fb248c04 JS |
155 | |
156 | def process(self): | |
157 | zero_time = ((self.rise - self.fall_start) / self.samplerate) * 1000.0 | |
158 | total_time = ((self.fall_end - self.fall_start) / self.samplerate) * 1000.0 | |
159 | pulse = Pulse.INVALID | |
160 | ||
161 | # VALIDATION: Identify pulse based on length of the low period | |
162 | for key in timing: | |
163 | if zero_time >= timing[key]['low']['min'] and zero_time <= timing[key]['low']['max']: | |
164 | pulse = key | |
165 | break | |
166 | ||
167 | # VALIDATION: Invalid pulse | |
168 | if pulse == Pulse.INVALID: | |
e8c1209d | 169 | self.stat = Stat.WAIT_START |
fb248c04 JS |
170 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Invalid pulse: Wrong timing']]) |
171 | return | |
172 | ||
173 | # VALIDATION: If waiting for start, discard everything else | |
174 | if self.stat == Stat.WAIT_START and pulse != Pulse.START: | |
175 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Expected START: BIT found']]) | |
176 | return | |
177 | ||
178 | # VALIDATION: If waiting for ACK or EOM, only BIT pulses (0/1) are expected | |
179 | if (self.stat == Stat.WAIT_ACK or self.stat == Stat.WAIT_EOM) and pulse == Pulse.START: | |
180 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Expected BIT: START received)']]) | |
e8c1209d | 181 | self.stat = Stat.WAIT_START |
fb248c04 JS |
182 | |
183 | # VALIDATION: ACK bit pulse remains high till the next frame (if any): Validate only min time of the low period | |
184 | if self.stat == Stat.WAIT_ACK and pulse != Pulse.START: | |
185 | if total_time < timing[pulse]['total']['min']: | |
186 | pulse = Pulse.INVALID | |
187 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['ACK pulse below minimun time']]) | |
e8c1209d | 188 | self.stat = Stat.WAIT_START |
fb248c04 JS |
189 | return |
190 | ||
191 | # VALIDATION / PING FRAME DETECTION: Initiator doesn't sets the EOM = 1 but stops sending when ack doesn't arrive | |
192 | if self.stat == Stat.GET_BITS and pulse == Pulse.START: | |
193 | # Make sure we received a complete byte to consider it a valid ping | |
194 | if self.bit_count == 0: | |
195 | self.handle_frame(self.is_nack) | |
196 | else: | |
197 | self.put(self.frame_start, self.samplenum, self.out_ann, [9, ['ERROR: Incomplete byte received']]) | |
198 | ||
199 | # Set wait start so we receive next frame | |
e8c1209d | 200 | self.stat = Stat.WAIT_START |
fb248c04 JS |
201 | |
202 | # VALIDATION: Check timing of the BIT (0/1) pulse in any other case (not waiting for ACK) | |
203 | if self.stat != Stat.WAIT_ACK and pulse != Pulse.START: | |
204 | if total_time < timing[pulse]['total']['min'] or total_time > timing[pulse]['total']['max']: | |
205 | self.put(self.fall_start, self.fall_end, self.out_ann, [9, ['Bit pulse exceeds total pulse timespan']]) | |
206 | pulse = Pulse.INVALID | |
e8c1209d | 207 | self.stat = Stat.WAIT_START |
fb248c04 JS |
208 | return |
209 | ||
210 | if pulse == Pulse.ZERO: | |
211 | bit = 0 | |
212 | elif pulse == Pulse.ONE: | |
213 | bit = 1 | |
214 | ||
215 | # STATE: WAIT START | |
216 | if self.stat == Stat.WAIT_START: | |
e8c1209d | 217 | self.stat = Stat.GET_BITS |
fb248c04 JS |
218 | self.reset_frame_vars() |
219 | self.put(self.fall_start, self.fall_end, self.out_ann, [0, ['ST']]) | |
220 | ||
221 | # STATE: GET BITS | |
222 | elif self.stat == Stat.GET_BITS: | |
223 | # Reset stats on first bit | |
224 | if self.bit_count == 0: | |
225 | self.byte_start = self.fall_start | |
226 | self.byte = 0 | |
227 | ||
228 | # If 1st byte of the datagram save its sample num | |
229 | if len(self.cmd_bytes) == 0: | |
230 | self.frame_start = self.fall_start | |
231 | ||
232 | self.byte += (bit << (7 - self.bit_count)) | |
233 | self.bit_count += 1 | |
234 | self.put(self.fall_start, self.fall_end, self.out_ann, [5, [str(bit)]]) | |
235 | ||
236 | if self.bit_count == 8: | |
237 | self.bit_count = 0 | |
238 | self.byte_count += 1 | |
e8c1209d | 239 | self.stat = Stat.WAIT_EOM |
fb248c04 JS |
240 | self.put(self.byte_start, self.samplenum, self.out_ann, [6, ['0x{:02x}'.format(self.byte)]]) |
241 | self.cmd_bytes.append({'st': self.byte_start, 'ed': self.samplenum, 'val': self.byte}) | |
242 | ||
243 | # STATE: WAIT EOM | |
244 | elif self.stat == Stat.WAIT_EOM: | |
245 | self.eom = bit | |
246 | self.frame_end = self.fall_end | |
247 | ||
8a8b516a UH |
248 | a = [2, ['EOM=Y']] if self.eom else [1, ['EOM=N']] |
249 | self.put(self.fall_start, self.fall_end, self.out_ann, a) | |
fb248c04 | 250 | |
e8c1209d | 251 | self.stat = Stat.WAIT_ACK |
fb248c04 JS |
252 | |
253 | # STATE: WAIT ACK | |
254 | elif self.stat == Stat.WAIT_ACK: | |
255 | # If a frame with broadcast destination is being sent, the ACK is | |
256 | # inverted: a 0 is considered a NACK, therefore we invert the value | |
257 | # of the bit here, so we match the real meaning of it. | |
258 | if (self.cmd_bytes[0]['val'] & 0x0F) == 0x0F: | |
259 | bit = ~bit & 0x01 | |
260 | ||
261 | if (self.fall_end - self.fall_start) > self.max_ack_len_samples: | |
262 | ann_end = self.fall_start + self.max_ack_len_samples | |
263 | else: | |
264 | ann_end = self.fall_end | |
265 | ||
266 | if bit: | |
267 | # Any NACK detected in the frame is enough to consider the | |
268 | # whole frame NACK'd. | |
269 | self.is_nack = 1 | |
270 | self.put(self.fall_start, ann_end, self.out_ann, [3, ['NACK']]) | |
271 | else: | |
272 | self.put(self.fall_start, ann_end, self.out_ann, [4, ['ACK']]) | |
273 | ||
274 | # After ACK bit, wait for new datagram or continue reading current | |
275 | # one based on EOM value. | |
276 | if self.eom or self.is_nack: | |
e8c1209d | 277 | self.stat = Stat.WAIT_START |
fb248c04 JS |
278 | self.handle_frame(self.is_nack) |
279 | else: | |
e8c1209d | 280 | self.stat = Stat.GET_BITS |
fb248c04 JS |
281 | |
282 | def start(self): | |
283 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
284 | ||
285 | def decode(self): | |
286 | if not self.samplerate: | |
287 | raise SamplerateError('Cannot decode without samplerate.') | |
288 | ||
289 | # Wait for first falling edge. | |
290 | self.wait({0: 'f'}) | |
291 | self.fall_end = self.samplenum | |
292 | ||
293 | while True: | |
294 | self.wait({0: 'r'}) | |
295 | self.rise = self.samplenum | |
296 | ||
297 | if self.stat == Stat.WAIT_ACK: | |
298 | self.wait([{0: 'f'}, {'skip': self.max_ack_len_samples}]) | |
299 | else: | |
300 | self.wait([{0: 'f'}]) | |
301 | ||
302 | self.fall_start = self.fall_end | |
303 | self.fall_end = self.samplenum | |
304 | self.process() | |
305 | ||
306 | # If there was a timeout while waiting for ACK: RESYNC. | |
307 | # Note: This is an expected situation as no new falling edge will | |
308 | # happen until next frame is transmitted. | |
309 | if self.matched == (False, True): | |
310 | self.wait({0: 'f'}) | |
311 | self.fall_end = self.samplenum |