2 * Copyright (C) 2015, 2016 "IoT.bzh"
3 * Author "Romain Forlot" <romain.forlot@iot.bzh>
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
18 #include "can-decoder.hpp"
21 #include "canutil/read.h"
22 #include "../utils/openxc-utils.hpp"
23 #include "message-definition.hpp"
24 #include "../binding/low-can-hat.hpp"
25 #include "../utils/converter.hpp"
27 /// @brief Handle sign of the signal according to several decoding methods
29 /// @param[in] signal - The signal
30 /// @param[in] data_signal - The data of the signal
31 /// @param[in] new_end_bit - The last bit of in the last byte of the data (data_signal[0])
32 /// @param[in] can_data - The whole can data (needed for SIGN BIT EXTERN)
34 /// @return Returns the sign of the data
36 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)
38 uint8_t data_byte = 0;
42 if(signal.get_sign() == sign_t::UNSIGNED)
44 else if(signal.get_sign() == sign_t::SIGN_BIT_EXTERN) {
45 end_bit = signal.get_bit_sign_position() % CHAR_BIT;
46 mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
47 data_byte = can_data[signal.get_bit_sign_position() / CHAR_BIT] & mask;
50 end_bit = new_end_bit;
51 mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
52 data_byte = data_signal[0] & mask;
55 //if negative: decode with right method
56 if(data_byte >> end_bit) {
57 switch(signal.get_sign())
59 //remove the sign bit to get the absolute value
60 case sign_t::SIGN_BIT:
61 data_signal[0] = static_cast<uint8_t>(data_signal[0] & (mask >> 1));
63 //same method twos complement = ones complement + 1
64 case sign_t::ONES_COMPLEMENT:
65 case sign_t::TWOS_COMPLEMENT:
66 //complement only until end_bit
67 data_signal[0] = ((data_signal[0] ^ mask) & mask);
68 if(data_signal.size() > 1) {
69 for(int i=1; i < data_signal.size(); i++) {
70 data_signal[i] = data_signal[i] ^ 0xFF;
73 if(signal.get_sign() == sign_t::TWOS_COMPLEMENT)
74 data_signal[data_signal.size() - 1] = static_cast<uint8_t>(data_signal[data_signal.size() - 1] + 1);
76 case sign_t::SIGN_BIT_EXTERN:
79 AFB_ERROR("Not a valid sign entry %d, considering the value as unsigned", signal.get_sign());
87 /// @brief Parses the signal's bitfield from the given data and returns the raw
90 /// @param[in] signal - The signal to be parsed from the data.
91 /// @param[in] message - message_t to parse
93 /// @return Returns the raw value of the signal parsed as a bitfield from the given byte
96 float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message_t> message)
99 std::vector<uint8_t> data;
100 std::vector<uint8_t> data_signal;
101 uint8_t bit_size = (uint8_t) signal.get_bit_size();
102 uint32_t bit_position = signal.get_bit_position();
104 int new_start_byte = 0;
105 int new_end_byte = 0;
106 uint8_t new_start_bit = 0;
107 uint8_t new_end_bit = 0;
109 if(signal.get_message()->frame_layout_is_bigendian())
111 bit_position = converter_t::bit_position_swap(message->get_length(),
112 signal.get_bit_position(),
114 message->frame_swap();
117 data = message->get_data_vector();
118 converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);
120 for(int i=new_start_byte;i<=new_end_byte;i++)
121 data_signal.push_back(data[i]);
123 sign = handle_sign(signal, data_signal, new_end_bit, data);
125 if(data_signal.size() > 65535)
126 AFB_ERROR("Too long data signal %s", signal.get_name().c_str());
128 return static_cast<float>(sign) * bitfield_parse_float(data_signal.data(), (uint16_t) data_signal.size(),
129 new_start_bit, bit_size, signal.get_factor(),
130 signal.get_offset());
134 /// @brief Decode and return string bytes (hex) for a CAN signal's.
136 /// This is an implementation of the Signal type signature, and can be
137 /// used directly in the signal_t.decoder field.
139 /// @param[in] signal - The details of the signal.
140 /// @param[in] message - The message with data to decode.
141 /// @param[out] send - An output argument that will be set to false if the value should
142 /// not be sent for any reason.
144 /// @return Returns a DynamicField with a string value of bytes (hex)
146 openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
149 openxc_DynamicField decoded_value;
150 std::vector<uint8_t> data = message->get_data_vector();
151 uint32_t length = message->get_length();
152 uint32_t bit_position = signal.get_bit_position();
153 uint32_t bit_size = signal.get_bit_size();
155 std::vector<uint8_t> new_data = std::vector<uint8_t>();
156 new_data.reserve((bit_size / CHAR_BIT) + 1);
158 int new_start_byte = 0;
159 int new_end_byte = 0;
160 uint8_t new_start_bit = 0;
161 uint8_t new_end_bit = 0;
163 converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);
165 if(new_end_byte >= length)
166 new_end_byte = length-1;
168 if(new_start_byte >= length)
170 AFB_ERROR("Error in signal's description");
171 return decoded_value;
174 uint8_t mask_first_v = static_cast<uint8_t>(0xFF << new_start_bit);
175 uint8_t mask_last_v = static_cast<uint8_t>(0xFF >> (7 - new_end_bit));
177 if(new_start_byte == new_end_byte)
179 data[new_start_byte] = data[new_start_byte] & (mask_first_v & mask_last_v);
183 data[new_start_byte] = data[new_start_byte] & mask_first_v;
184 data[new_end_byte] = data[new_end_byte] & mask_last_v;
187 for(i=new_start_byte ; i <= new_end_byte ; i++)
188 new_data.push_back(data[i]);
190 decoded_value = build_DynamicField(new_data);
192 return decoded_value;
195 /// @brief Wraps a raw CAN signal value in a DynamicField without modification.
197 /// This is an implementation of the Signal type signature, and can be
198 /// used directly in the signal_t.decoder field.
200 /// @param[in] signal - The details of the signal that contains the state mapping.
201 /// @param[in] message - The message with data to decode.
202 /// @param[out] send - An output argument that will be set to false if the value should
203 /// not be sent for any reason.
205 /// @return Returns a DynamicField with the original, unmodified raw CAN signal value as
206 /// its numeric value. The 'send' argument will not be modified as this decoder
209 openxc_DynamicField decoder_t::decode_noop(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
211 float value = decoder_t::parse_signal_bitfield(signal, message);
212 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
213 openxc_DynamicField decoded_value = build_DynamicField(value);
215 // Don't send if they is no changes
216 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
220 signal.set_last_value(value);
222 return decoded_value;
224 /// @brief Coerces a numerical value to a boolean.
226 /// This is an implementation of the Signal type signature, and can be
227 /// used directly in the signal_t.decoder field.
229 /// @param[in] signal - The details of the signal that contains the state mapping.
230 /// @param[in] message - The message with data to decode.
231 /// @param[out] send - An output argument that will be set to false if the value should
232 /// not be sent for any reason.
234 /// @return Returns a DynamicField with a boolean value of false if the raw signal value
235 /// is 0.0, otherwise true. The 'send' argument will not be modified as this
236 /// decoder always succeeds.
238 openxc_DynamicField decoder_t::decode_boolean(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
240 float value = decoder_t::parse_signal_bitfield(signal, message);
241 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
242 openxc_DynamicField decoded_value = build_DynamicField(value == 0.0 ? false : true);
244 // Don't send if they is no changes
245 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
248 signal.set_last_value(value);
251 return decoded_value;
253 /// @brief Update the metadata for a signal and the newly received value.
255 /// This is an implementation of the Signal type signature, and can be
256 /// used directly in the signal_t.decoder field.
258 /// This function always flips 'send' to false.
260 /// @param[in] signal - The details of the signal that contains the state mapping.
261 /// @param[in] message - The message with data to decode.
262 /// @param[out] send - This output argument will always be set to false, so the caller will
263 /// know not to publish this value to the pipeline.
265 /// @return Return value is undefined.
267 openxc_DynamicField decoder_t::decode_ignore(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
269 float value = decoder_t::parse_signal_bitfield(signal, message);
273 signal.set_last_value(value);
274 openxc_DynamicField decoded_value;
276 return decoded_value;
279 /// @brief Find and return the corresponding string state for a CAN signal's
280 /// raw integer value.
282 /// This is an implementation of the Signal type signature, and can be
283 /// used directly in the signal_t.decoder field.
285 /// @param[in] signal - The details of the signal that contains the state mapping.
286 /// @param[in] message - The message with data to decode.
287 /// @param[out] send - An output argument that will be set to false if the value should
288 /// not be sent for any reason.
290 /// @return Returns a DynamicField with a string value if a matching state is found in
291 /// the signal. If an equivalent isn't found, send is sent to false and the
292 /// return value is undefined.
294 openxc_DynamicField decoder_t::decode_state(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
296 float value = decoder_t::parse_signal_bitfield(signal, message);
297 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
298 const std::string signal_state = signal.get_states((uint8_t)value);
299 openxc_DynamicField decoded_value = build_DynamicField(signal_state);
300 if(signal_state.size() <= 0)
303 AFB_ERROR("No state found with index: %d", (int)value);
306 // Don't send if they is no changes
307 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
311 signal.set_last_value(value);
314 return decoded_value;
318 /// @brief Parse a signal from a CAN message, apply any required transforations
319 /// to get a human readable value and public the result to the pipeline.
321 /// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
322 /// will be passed to the decoder before publishing.
324 /// @param[in] signal - The details of the signal to decode and forward.
325 /// @param[in] message - The message with data to decode.
326 /// @param[out] send - An output parameter that will be flipped to false if the value could
329 /// The decoder returns an openxc_DynamicField, which may contain a number,
330 /// string or boolean.
332 openxc_DynamicField decoder_t::translate_signal(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
334 // Must call the decoders every time, regardless of if we are going to
335 // decide to send the signal or not.
336 openxc_DynamicField decoded_value = decoder_t::decode_signal(signal,
339 signal.set_received(true);
340 signal.set_timestamp(message->get_timestamp());
341 signal.get_message()->set_last_value(message);
342 return decoded_value;
345 /// @brief Parse a signal from a CAN message and apply any required
346 /// transforations to get a human readable value.
348 /// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
349 /// will be passed to the decoder before returning.
351 /// @param[in] signal - The details of the signal to decode and forward.
352 /// @param[in] message - The message with data to decode.
353 /// @param[out] send - An output parameter that will be flipped to false if the value could
356 /// @return The decoder returns an openxc_DynamicField, which may contain a number,
357 /// string or boolean. If 'send' is false, the return value is undefined.
359 openxc_DynamicField decoder_t::decode_signal( signal_t& signal, std::shared_ptr<message_t> message, bool* send)
361 signal_decoder decoder = signal.get_decoder() == nullptr ?
362 decode_noop : signal.get_decoder();
364 openxc_DynamicField decoded_value = decoder(signal,
366 return decoded_value;
370 /// @brief Decode the payload of an OBD-II PID.
372 /// This function matches the type signature for a DiagnosticResponse, so
373 /// it can be used as the decoder for a DiagnosticRequest. It returns the decoded
374 /// value of the PID, using the standard formulas (see
375 /// http://en.wikipedia.org/wiki/OBD-II_PIDs#Mode_01).
377 /// @param[in] response - the received DiagnosticResponse (the data is in response.payload,
378 /// a byte array). This is most often used when the byte order is
379 /// signiticant, i.e. with many OBD-II PID formulas.
380 /// @param[in] parsed_payload - the entire payload of the response parsed as an int.
382 /// @return Float decoded value.
384 float decoder_t::decode_obd2_response(const DiagnosticResponse* response, float parsed_payload)
386 return diagnostic_decode_obd2_pid(response);