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Diffstat (limited to 'src/can-decoder.hpp')
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1 files changed, 146 insertions, 0 deletions
diff --git a/src/can-decoder.hpp b/src/can-decoder.hpp new file mode 100644 index 0000000..b6234b5 --- /dev/null +++ b/src/can-decoder.hpp @@ -0,0 +1,146 @@ +/* + * 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. + */ + +#pragma once + + +class decoder_t +{ + private: + openxc_DynamicField decoded_value; + + public: + /* Public: Parse the signal's bitfield from the given data and return the raw + * value. + * + * signal - The signal to parse from the data. + * data - The data to parse the signal from. + * length - The length of the data array. + * + * Returns the raw value of the signal parsed as a bitfield from the given byte + * array. + */ + float parseSignalBitfield(const CanSignal& signal, const CanMessage& message); + + /* Public: Find and return the corresponding string state for a CAN signal's + * raw integer value. + * + * This is an implementation of the SignalDecoder type signature, and can be + * used directly in the CanSignal.decoder field. + * + * signal - The details of the signal that contains the state mapping. + * signals - The list of all signals. + * signalCount - the length of the signals array. + * value - The numerical value that should map to a state. + * send - An output argument that will be set to false if the value should + * not be sent for any reason. + * + * 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 stateDecoder(const CanSignal& signal, const CanSignal& signals, + float value, bool* send); + + /* Public: Coerces a numerical value to a boolean. + * + * This is an implementation of the SignalDecoder type signature, and can be + * used directly in the CanSignal.decoder field. + * + * signal - The details of the signal that contains the state mapping. + * signals - The list of all signals + * signalCount - The length of the signals array + * value - The numerical value that will be converted to a boolean. + * send - An output argument that will be set to false if the value should + * not be sent for any reason. + * + * 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 booleanDecoder(const CanSignal& signal, const CanSignal& signals, + float value, bool* send); + + /* Public: Update the metadata for a signal and the newly received value. + * + * This is an implementation of the SignalDecoder type signature, and can be + * used directly in the CanSignal.decoder field. + * + * This function always flips 'send' to false. + * + * signal - The details of the signal that contains the state mapping. + * signals - The list of all signals. + * signalCount - The length of the signals array. + * value - The numerical value that will be converted to a boolean. + * send - This output argument will always be set to false, so the caller will + * know not to publish this value to the pipeline. + * + * The return value is undefined. + */ + openxc_DynamicField ignoreDecoder(const CanSignal& signal, const CanSignal& signals, + float value, bool* send); + + /* Public: Wrap a raw CAN signal value in a DynamicField without modification. + * + * This is an implementation of the SignalDecoder type signature, and can be + * used directly in the CanSignal.decoder field. + * + * signal - The details of the signal that contains the state mapping. + * signals - The list of all signals + * signalCount - The length of the signals array + * value - The numerical value that will be wrapped in a DynamicField. + * send - An output argument that will be set to false if the value should + * not be sent for any reason. + * + * 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 noopDecoder(const CanSignal& signal, const CanSignal& signals, + float value, bool* send); + + /* Public: Parse a signal from a CAN message and apply any required + * transforations to get a human readable value. + * + * If the CanSignal has a non-NULL 'decoder' field, the raw CAN signal value + * will be passed to the decoder before returning. + * + * signal - The details of the signal to decode and forward. + * message - The CAN message that contains the signal. + * signals - an array of all active signals. + * signalCount - The length of the signals array. + * 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. If 'send' is false, the return value is undefined. + */ + openxc_DynamicField decodeSignal(const CanSignal& signal, + const CanMessage& message, const CanSignal& signals, + bool* send); + + /* Public: Decode a transformed, human readable value from an raw CAN signal + * already parsed from a CAN message. + * + * This is the same as decodeSignal(const CanSignal&, CanMessage*, const CanSignal&, int, + * bool*) but you must parse the bitfield value of the signal from the CAN + * message yourself. This is useful if you need that raw value for something + * else. + */ + openxc_DynamicField decodeSignal(const CanSignal& signal, float value, + const CanSignal& signals, bool* send); +}
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