aboutsummaryrefslogtreecommitdiffstats
path: root/low-can-binding/can/can-decoder.cpp
blob: ae10cd980ae8c2b678e5c48155d45835148d7f94 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
/*
 * Copyright (C) 2015, 2016 "IoT.bzh"
 * Author "Romain Forlot" <romain.forlot@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	 http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "can-decoder.hpp"
#include <climits>

#include "canutil/read.h"
#include "../utils/openxc-utils.hpp"
#include "message-definition.hpp"
#include "../binding/low-can-hat.hpp"
#include "../utils/converter.hpp"

/// @brief Handle sign of the signal according to several decoding methods
///
/// @param[in] signal - The signal
/// @param[in] data_signal - The data of the signal
/// @param[in] new_end_bit - The last bit of in the last byte of the data (data_signal[0])
/// @param[in] can_data - The whole can data (needed for SIGN BIT EXTERN)
///
/// @return Returns the sign of the data
///
int decoder_t::handle_sign(const signal_t& signal, std::vector<uint8_t>& data_signal, uint8_t new_end_bit, const std::vector<uint8_t>& can_data)
{
	uint8_t data_byte = 0;
	uint8_t mask = 0;
	int end_bit = 0;

	if(signal.get_sign() == sign_t::UNSIGNED)
		return 1;
	else if(signal.get_sign() == sign_t::SIGN_BIT_EXTERN) {
		end_bit = signal.get_bit_sign_position() % CHAR_BIT;
		mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
		data_byte = can_data[signal.get_bit_sign_position() / CHAR_BIT] & mask;
	}
	else {
		end_bit = new_end_bit;
		mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
		data_byte = data_signal[0] & mask;
	}

	//if negative: decode with right method
	if(data_byte  >> end_bit) {
		switch(signal.get_sign())
		{
			//remove the sign bit to get the absolute value
			case sign_t::SIGN_BIT:
				data_signal[0] = static_cast<uint8_t>(data_signal[0] & (mask >> 1));
				break;
			//same method twos complement = ones complement + 1
			case sign_t::ONES_COMPLEMENT:
			case sign_t::TWOS_COMPLEMENT:
				//complement only until end_bit
				data_signal[0] = ((data_signal[0] ^ mask) & mask);
				if(data_signal.size() > 1) {
					for(int i=1; i < data_signal.size(); i++) {
						data_signal[i] = data_signal[i] ^ 0xFF;
					}
				}
				if(signal.get_sign() == sign_t::TWOS_COMPLEMENT)
					data_signal[data_signal.size() - 1] = static_cast<uint8_t>(data_signal[data_signal.size() - 1] + 1);
				break;
			case sign_t::SIGN_BIT_EXTERN:
				break;
			default:
				AFB_ERROR("Not a valid sign entry %d, considering the value as unsigned", signal.get_sign());
				break;
		}
		return -1;
	}
	return 1;
}

/// @brief Parses the signal's bitfield from the given data and returns the raw
/// value.
///
/// @param[in] signal - The signal to be parsed from the data.
/// @param[in] message - message_t to parse
///
/// @return Returns the raw value of the signal parsed as a bitfield from the given byte
/// array.
///
float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message_t> message)
{
	int sign;
	std::vector<uint8_t> data;
	std::vector<uint8_t> data_signal;
	uint8_t bit_size = (uint8_t) signal.get_bit_size();
	uint32_t bit_position = signal.get_bit_position();

	int new_start_byte = 0;
	int new_end_byte = 0;
	uint8_t new_start_bit = 0;
	uint8_t new_end_bit = 0;

	if(signal.get_message()->frame_layout_is_bigendian())
	{
		bit_position = converter_t::bit_position_swap(message->get_length(),
							      signal.get_bit_position(),
							      bit_size);
		message->frame_swap();
	}

	data = message->get_data_vector();
	converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);

	for(int i=new_start_byte;i<=new_end_byte;i++)
		data_signal.push_back(data[i]);

	sign = handle_sign(signal, data_signal, new_end_bit, data);

	if(data_signal.size() > 65535)
		AFB_ERROR("Too long data signal %s", signal.get_name().c_str());

	return static_cast<float>(sign) * bitfield_parse_float(data_signal.data(), (uint16_t) data_signal.size(),
			new_start_bit, bit_size, signal.get_factor(),
			signal.get_offset());
}


/// @brief Decode and return string bytes (hex) for a CAN signal's.
///
/// This is an implementation of the Signal type signature, and can be
/// used directly in the signal_t.decoder field.
///
/// @param[in] signal  - The details of the signal.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output argument that will be set to false if the value should
///     not be sent for any reason.
///
/// @return Returns a DynamicField with a string value of bytes (hex)
///
openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	int i=0;
	openxc_DynamicField decoded_value;
	std::vector<uint8_t> data = message->get_data_vector();
	uint32_t length = message->get_length();
	uint32_t bit_position = signal.get_bit_position();
	uint32_t bit_size = signal.get_bit_size();

	std::vector<uint8_t> new_data = std::vector<uint8_t>();
	new_data.reserve((bit_size / CHAR_BIT) + 1);

	int new_start_byte = 0;
	int new_end_byte = 0;
	uint8_t new_start_bit = 0;
	uint8_t new_end_bit = 0;

	converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);

	if(new_end_byte >= length)
		new_end_byte = length-1;

	if(new_start_byte >= length)
	{
		AFB_ERROR("Error in signal's description");
		return decoded_value;
	}

	uint8_t mask_first_v = static_cast<uint8_t>(0xFF << new_start_bit);
	uint8_t mask_last_v = static_cast<uint8_t>(0xFF >> (7 - new_end_bit));

	if(new_start_byte == new_end_byte)
	{
		data[new_start_byte] = data[new_start_byte] & (mask_first_v & mask_last_v);
	}
	else
	{
		data[new_start_byte] = data[new_start_byte] & mask_first_v;
		data[new_end_byte] = data[new_end_byte] & mask_last_v;
	}

	for(i=new_start_byte ; i <= new_end_byte ; i++)
		new_data.push_back(data[i]);

	decoded_value = build_DynamicField(new_data);

	return decoded_value;
}

/// @brief Wraps a raw CAN signal value in a DynamicField without modification.
///
/// This is an implementation of the Signal type signature, and can be
/// used directly in the signal_t.decoder field.
///
/// @param[in] signal - The details of the signal that contains the state mapping.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output argument that will be set to false if the value should
///     not be sent for any reason.
///
/// @return Returns a DynamicField with the original, unmodified raw CAN signal value as
/// its numeric value. The 'send' argument will not be modified as this decoder
/// always succeeds.
///
openxc_DynamicField decoder_t::decode_noop(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	float value = decoder_t::parse_signal_bitfield(signal, message);
	AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
	openxc_DynamicField decoded_value = build_DynamicField(value);

	// Don't send if they is no changes
	if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
	{
		*send = false;
	}
	signal.set_last_value(value);

	return decoded_value;
}
/// @brief Coerces a numerical value to a boolean.
///
/// This is an implementation of the Signal type signature, and can be
/// used directly in the signal_t.decoder field.
///
/// @param[in] signal  - The details of the signal that contains the state mapping.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output argument that will be set to false if the value should
///     not be sent for any reason.
///
/// @return Returns a DynamicField with a boolean value of false if the raw signal value
/// is 0.0, otherwise true. The 'send' argument will not be modified as this
/// decoder always succeeds.
///
openxc_DynamicField decoder_t::decode_boolean(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	float value = decoder_t::parse_signal_bitfield(signal, message);
	AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
	openxc_DynamicField decoded_value = build_DynamicField(value == 0.0 ? false : true);

	// Don't send if they is no changes
	if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
		*send = false;

	signal.set_last_value(value);


	return decoded_value;
}
/// @brief Update the metadata for a signal and the newly received value.
///
/// This is an implementation of the Signal type signature, and can be
/// used directly in the signal_t.decoder field.
///
/// This function always flips 'send' to false.
///
/// @param[in] signal  - The details of the signal that contains the state mapping.
/// @param[in] message - The message with data to decode.
/// @param[out] send - This output argument will always be set to false, so the caller will
///      know not to publish this value to the pipeline.
///
/// @return Return value is undefined.
///
openxc_DynamicField decoder_t::decode_ignore(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	float value = decoder_t::parse_signal_bitfield(signal, message);
	if(send)
	  *send = false;

	signal.set_last_value(value);
	openxc_DynamicField decoded_value;

	return decoded_value;
}

/// @brief Find and return the corresponding string state for a CAN signal's
/// raw integer value.
///
/// This is an implementation of the Signal type signature, and can be
/// used directly in the signal_t.decoder field.
///
/// @param[in] signal  - The details of the signal that contains the state mapping.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output argument that will be set to false if the value should
///     not be sent for any reason.
///
/// @return Returns a DynamicField with a string value if a matching state is found in
/// the signal. If an equivalent isn't found, send is sent to false and the
/// return value is undefined.
///
openxc_DynamicField decoder_t::decode_state(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	float value = decoder_t::parse_signal_bitfield(signal, message);
	AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
	const std::string signal_state = signal.get_states((uint8_t)value);
	openxc_DynamicField decoded_value = build_DynamicField(signal_state);
	if(signal_state.size() <= 0)
	{
		*send = false;
		AFB_ERROR("No state found with index: %d", (int)value);
	}

	// Don't send if they is no changes
	if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
	{
		*send = false;
	}
	signal.set_last_value(value);


	return decoded_value;
}


/// @brief Parse a signal from a CAN message, apply any required transforations
///      to get a human readable value and public the result to the pipeline.
///
/// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
/// will be passed to the decoder before publishing.
///
/// @param[in] signal - The details of the signal to decode and forward.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output parameter that will be flipped to false if the value could
///      not be decoded.
///
/// The decoder returns an openxc_DynamicField, which may contain a number,
/// string or boolean.
///
openxc_DynamicField decoder_t::translate_signal(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	// Must call the decoders every time, regardless of if we are going to
	// decide to send the signal or not.
	openxc_DynamicField decoded_value = decoder_t::decode_signal(signal,
			message, send);

	signal.set_received(true);
	signal.set_timestamp(message->get_timestamp());
	signal.get_message()->set_last_value(message);
	return decoded_value;
}

/// @brief Parse a signal from a CAN message and apply any required
/// transforations to get a human readable value.
///
/// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
/// will be passed to the decoder before returning.
///
/// @param[in] signal - The details of the signal to decode and forward.
/// @param[in] message - The message with data to decode.
/// @param[out] send - An output parameter that will be flipped to false if the value could
///      not be decoded.
///
/// @return The decoder returns an openxc_DynamicField, which may contain a number,
/// string or boolean. If 'send' is false, the return value is undefined.
///
openxc_DynamicField decoder_t::decode_signal( signal_t& signal, std::shared_ptr<message_t> message, bool* send)
{
	signal_decoder decoder = signal.get_decoder() == nullptr ?
							decode_noop : signal.get_decoder();

	openxc_DynamicField decoded_value = decoder(signal,
			message, send);
	return decoded_value;
}

///
/// @brief Decode the payload of an OBD-II PID.
///
/// This function matches the type signature for a DiagnosticResponse, so
/// it can be used as the decoder for a DiagnosticRequest. It returns the decoded
/// value of the PID, using the standard formulas (see
/// http://en.wikipedia.org/wiki/OBD-II_PIDs#Mode_01).
///
/// @param[in] response - the received DiagnosticResponse (the data is in response.payload,
///  a byte array). This is most often used when the byte order is
///  signiticant, i.e. with many OBD-II PID formulas.
/// @param[in] parsed_payload - the entire payload of the response parsed as an int.
///
/// @return Float decoded value.
///
float decoder_t::decode_obd2_response(const DiagnosticResponse* response, float parsed_payload)
{
	return diagnostic_decode_obd2_pid(response);
}