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"
20 #include "canutil/read.h"
21 #include "../utils/openxc-utils.hpp"
22 #include "message-definition.hpp"
23 #include "../binding/low-can-hat.hpp"
24 #include "../utils/converter.hpp"
26 /// @brief Handle sign of the signal according to several decoding methods
28 /// @param[in] signal - The signal
29 /// @param[in] data_signal - The data of the signal
30 /// @param[in] new_end_bit - The last bit of in the last byte of the data (data_signal[0])
31 /// @param[in] can_data - The whole can data (needed for SIGN BIT EXTERN)
33 /// @return Returns the sign of the data
35 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)
37 uint8_t data_byte = 0;
41 if(signal.get_sign() == sign_t::UNSIGNED)
43 else if(signal.get_sign() == sign_t::SIGN_BIT_EXTERN) {
44 end_bit = signal.get_bit_sign_position()%8;
45 mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
46 data_byte = can_data[signal.get_bit_sign_position()/8] & mask;
49 end_bit = new_end_bit;
50 mask = static_cast<uint8_t>((1 << (end_bit + 1)) - 1);
51 data_byte = data_signal[0] & mask;
54 //if negative: decode with right method
55 if(data_byte >> end_bit) {
56 switch(signal.get_sign())
58 //remove the sign bit to get the absolute value
59 case sign_t::SIGN_BIT:
60 data_signal[0] = static_cast<uint8_t>(data_signal[0] & (mask >> 1));
62 //same method twos complement = ones complement + 1
63 case sign_t::ONES_COMPLEMENT:
64 case sign_t::TWOS_COMPLEMENT:
65 //complement only until end_bit
66 data_signal[0] = ((data_signal[0] ^ mask) & mask);
67 if(data_signal.size() > 1) {
68 for(int i=1; i < data_signal.size(); i++) {
69 data_signal[i] = data_signal[i] ^ 0xFF;
72 if(signal.get_sign() == sign_t::TWOS_COMPLEMENT)
73 data_signal[data_signal.size() - 1] = static_cast<uint8_t>(data_signal[data_signal.size() - 1] + 1);
75 case sign_t::SIGN_BIT_EXTERN:
78 AFB_ERROR("Not a valid sign entry %d, considering the value as unsigned", signal.get_sign());
86 /// @brief Parses the signal's bitfield from the given data and returns the raw
89 /// @param[in] signal - The signal to be parsed from the data.
90 /// @param[in] message - message_t to parse
92 /// @return Returns the raw value of the signal parsed as a bitfield from the given byte
95 float decoder_t::parse_signal_bitfield(signal_t& signal, std::shared_ptr<message_t> message)
97 const std::vector<uint8_t> data = message->get_data_vector();
98 std::vector<uint8_t> data_signal;
99 uint8_t bit_size = (uint8_t) signal.get_bit_size();
100 uint32_t bit_position = signal.get_bit_position();
102 if(signal.get_message()->frame_layout_is_bigendian())
104 bit_position = converter_t::bit_position_swap(message->get_length(),
105 signal.get_bit_position(),
106 signal.get_bit_size());
107 message->frame_swap();
110 int new_start_byte = 0;
111 int new_end_byte = 0;
112 uint8_t new_start_bit = 0;
113 uint8_t new_end_bit = 0;
115 converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);
117 for(int i=new_start_byte;i<=new_end_byte;i++)
118 data_signal.push_back(data[i]);
120 int sign = decoder_t::handle_sign(signal, data_signal, new_end_bit, data);
122 if(data_signal.size() > 65535)
123 AFB_ERROR("Too long data signal %s", signal.get_name().c_str());
125 return static_cast<float>(sign) * bitfield_parse_float(data_signal.data(), (uint16_t) data_signal.size(),
126 new_start_bit, bit_size, signal.get_factor(),
127 signal.get_offset());
131 /// @brief Decode and return string bytes (hex) for a CAN signal's.
133 /// This is an implementation of the Signal type signature, and can be
134 /// used directly in the signal_t.decoder field.
136 /// @param[in] signal - The details of the signal.
137 /// @param[in] message - The message with data to decode.
138 /// @param[out] send - An output argument that will be set to false if the value should
139 /// not be sent for any reason.
141 /// @return Returns a DynamicField with a string value of bytes (hex)
143 openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
146 openxc_DynamicField decoded_value;
147 std::vector<uint8_t> data = message->get_data_vector();
148 uint32_t length = message->get_length();
149 uint32_t bit_position = signal.get_bit_position();
150 uint32_t bit_size = signal.get_bit_size();
152 std::vector<uint8_t> new_data = std::vector<uint8_t>();
153 new_data.reserve((bit_size / 8) + 1);
155 int new_start_byte = 0;
156 int new_end_byte = 0;
157 uint8_t new_start_bit = 0;
158 uint8_t new_end_bit = 0;
160 converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);
162 if(new_end_byte >= length)
163 new_end_byte = length-1;
165 if(new_start_byte >= length)
167 AFB_ERROR("Error in signal's description");
168 return decoded_value;
171 uint8_t mask_first_v = static_cast<uint8_t>(0xFF << new_start_bit);
172 uint8_t mask_last_v = static_cast<uint8_t>(0xFF >> (7 - new_end_bit));
174 if(new_start_byte == new_end_byte)
176 data[new_start_byte] = data[new_start_byte] & (mask_first_v & mask_last_v);
180 data[new_start_byte] = data[new_start_byte] & mask_first_v;
181 data[new_end_byte] = data[new_end_byte] & mask_last_v;
184 for(i=new_start_byte ; i <= new_end_byte ; i++)
185 new_data.push_back(data[i]);
187 decoded_value = build_DynamicField(new_data);
189 return decoded_value;
192 /// @brief Wraps a raw CAN signal value in a DynamicField without modification.
194 /// This is an implementation of the Signal type signature, and can be
195 /// used directly in the signal_t.decoder field.
197 /// @param[in] signal - The details of the signal that contains the state mapping.
198 /// @param[in] message - The message with data to decode.
199 /// @param[out] send - An output argument that will be set to false if the value should
200 /// not be sent for any reason.
202 /// @return Returns a DynamicField with the original, unmodified raw CAN signal value as
203 /// its numeric value. The 'send' argument will not be modified as this decoder
206 openxc_DynamicField decoder_t::decode_noop(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
208 float value = decoder_t::parse_signal_bitfield(signal, message);
209 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
210 openxc_DynamicField decoded_value = build_DynamicField(value);
212 // Don't send if they is no changes
213 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
217 signal.set_last_value(value);
219 return decoded_value;
221 /// @brief Coerces a numerical value to a boolean.
223 /// This is an implementation of the Signal type signature, and can be
224 /// used directly in the signal_t.decoder field.
226 /// @param[in] signal - The details of the signal that contains the state mapping.
227 /// @param[in] message - The message with data to decode.
228 /// @param[out] send - An output argument that will be set to false if the value should
229 /// not be sent for any reason.
231 /// @return Returns a DynamicField with a boolean value of false if the raw signal value
232 /// is 0.0, otherwise true. The 'send' argument will not be modified as this
233 /// decoder always succeeds.
235 openxc_DynamicField decoder_t::decode_boolean(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
237 float value = decoder_t::parse_signal_bitfield(signal, message);
238 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
239 openxc_DynamicField decoded_value = build_DynamicField(value == 0.0 ? false : true);
241 // Don't send if they is no changes
242 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
245 signal.set_last_value(value);
248 return decoded_value;
250 /// @brief Update the metadata for a signal and the newly received value.
252 /// This is an implementation of the Signal type signature, and can be
253 /// used directly in the signal_t.decoder field.
255 /// This function always flips 'send' to false.
257 /// @param[in] signal - The details of the signal that contains the state mapping.
258 /// @param[in] message - The message with data to decode.
259 /// @param[out] send - This output argument will always be set to false, so the caller will
260 /// know not to publish this value to the pipeline.
262 /// @return Return value is undefined.
264 openxc_DynamicField decoder_t::decode_ignore(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
266 float value = decoder_t::parse_signal_bitfield(signal, message);
270 signal.set_last_value(value);
271 openxc_DynamicField decoded_value;
273 return decoded_value;
276 /// @brief Find and return the corresponding string state for a CAN signal's
277 /// raw integer value.
279 /// This is an implementation of the Signal type signature, and can be
280 /// used directly in the signal_t.decoder field.
282 /// @param[in] signal - The details of the signal that contains the state mapping.
283 /// @param[in] message - The message with data to decode.
284 /// @param[out] send - An output argument that will be set to false if the value should
285 /// not be sent for any reason.
287 /// @return Returns a DynamicField with a string value if a matching state is found in
288 /// the signal. If an equivalent isn't found, send is sent to false and the
289 /// return value is undefined.
291 openxc_DynamicField decoder_t::decode_state(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
293 float value = decoder_t::parse_signal_bitfield(signal, message);
294 AFB_DEBUG("Decoded message from parse_signal_bitfield: %f", value);
295 const std::string signal_state = signal.get_states((uint8_t)value);
296 openxc_DynamicField decoded_value = build_DynamicField(signal_state);
297 if(signal_state.size() <= 0)
300 AFB_ERROR("No state found with index: %d", (int)value);
303 // Don't send if they is no changes
304 if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
308 signal.set_last_value(value);
311 return decoded_value;
315 /// @brief Parse a signal from a CAN message, apply any required transforations
316 /// to get a human readable value and public the result to the pipeline.
318 /// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
319 /// will be passed to the decoder before publishing.
321 /// @param[in] signal - The details of the signal to decode and forward.
322 /// @param[in] message - The message with data to decode.
323 /// @param[out] send - An output parameter that will be flipped to false if the value could
326 /// The decoder returns an openxc_DynamicField, which may contain a number,
327 /// string or boolean.
329 openxc_DynamicField decoder_t::translate_signal(signal_t& signal, std::shared_ptr<message_t> message, bool* send)
331 // Must call the decoders every time, regardless of if we are going to
332 // decide to send the signal or not.
333 openxc_DynamicField decoded_value = decoder_t::decode_signal(signal,
336 signal.set_received(true);
337 signal.set_timestamp(message->get_timestamp());
338 signal.get_message()->set_last_value(message);
339 return decoded_value;
342 /// @brief Parse a signal from a CAN message and apply any required
343 /// transforations to get a human readable value.
345 /// If the signal_t has a non-NULL 'decoder' field, the raw CAN signal value
346 /// will be passed to the decoder before returning.
348 /// @param[in] signal - The details of the signal to decode and forward.
349 /// @param[in] message - The message with data to decode.
350 /// @param[out] send - An output parameter that will be flipped to false if the value could
353 /// @return The decoder returns an openxc_DynamicField, which may contain a number,
354 /// string or boolean. If 'send' is false, the return value is undefined.
356 openxc_DynamicField decoder_t::decode_signal( signal_t& signal, std::shared_ptr<message_t> message, bool* send)
358 signal_decoder decoder = signal.get_decoder() == nullptr ?
359 decode_noop : signal.get_decoder();
361 openxc_DynamicField decoded_value = decoder(signal,
363 return decoded_value;
367 /// @brief Decode the payload of an OBD-II PID.
369 /// This function matches the type signature for a DiagnosticResponse, so
370 /// it can be used as the decoder for a DiagnosticRequest. It returns the decoded
371 /// value of the PID, using the standard formulas (see
372 /// http://en.wikipedia.org/wiki/OBD-II_PIDs#Mode_01).
374 /// @param[in] response - the received DiagnosticResponse (the data is in response.payload,
375 /// a byte array). This is most often used when the byte order is
376 /// signiticant, i.e. with many OBD-II PID formulas.
377 /// @param[in] parsed_payload - the entire payload of the response parsed as an int.
379 /// @return Float decoded value.
381 float decoder_t::decode_obd2_response(const DiagnosticResponse* response, float parsed_payload)
383 return diagnostic_decode_obd2_pid(response);