dbc_decoder.h

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/**
 * @file dbc_decoder.h
 * @brief
 *
 * Created: 2026-03-13
 * Author: Deeaitch (Dim. Himro)
 *
 * Licensed under the MIT License.
 * See LICENSE file in the project root for full license text.
 */
 
#ifndef DBC_DECODER_H
#define DBC_DECODER_H
 
#include <vector>
#include <cstdint>
 
#include "decode_database.h"
 
/**
 * @brief Raw CAN frame used for runtime or trace decoding.
 */
struct RawCanFrame {
  std::uint32_t canId;           /**< Normalized CAN ID. */
  bool isExtended;               /**< true for extended frame. */
  std::vector<std::uint8_t> data; /**< Payload bytes. */
 
  RawCanFrame()
    : canId (0U)
    , isExtended (false)
    , data() {
  }
};
 
/**
 * @brief One decoded signal value.
 */
struct DecodedSignalValue {
  const DecodeSignal *definition; /**< Signal definition. */
  std::int64_t rawValue;          /**< Extracted raw integer value. */
  double physicalValue;           /**< Converted physical value. */
  bool valid;                     /**< true if decoding succeeded. */
 
  DecodedSignalValue()
    : definition (nullptr)
    , rawValue (0)
    , physicalValue (0.0)
    , valid (false) {
  }
};
 
/**
 * @brief Fully decoded frame.
 */
struct DecodedFrameValue {
  const DecodeFrame *definition;          /**< Frame definition. */
  std::vector<DecodedSignalValue> signals; /**< Decoded signal values. */
  bool valid;                             /**< true if frame was matched. */
 
  DecodedFrameValue()
    : definition (nullptr)
    , signals()
    , valid (false) {
  }
};
 
/**
 * @brief Runtime CAN decoder using prebuilt decode database.
 */
class DbcDecoder {
  public:
    /**
     * @brief Find frame definition by CAN ID.
     * @param database Runtime decode database.
     * @param canId Normalized CAN ID.
     * @param isExtended true for extended frame.
     * @return Pointer to frame definition or nullptr.
     */
    const DecodeFrame *FindFrame (const DecodeDatabase &database,
                                  std::uint32_t canId,
                                  bool isExtended) const;
 
    /**
     * @brief Decode one raw CAN frame.
     * @param database Runtime decode database.
     * @param frame Raw CAN frame.
     * @return Decoded frame value.
     */
    DecodedFrameValue Decode (const DecodeDatabase &database,
                              const RawCanFrame &frame) const;
 
  private:
    static bool ExtractUnsigned (const std::vector<std::uint8_t> &data,
                                 const DecodeSignal &signal,
                                 std::uint64_t &value);
 
    static bool ExtractIntel (const std::vector<std::uint8_t> &data,
                              std::uint32_t startBit,
                              std::uint32_t length,
                              std::uint64_t &value);
 
    static bool ExtractMotorola (const std::vector<std::uint8_t> &data,
                                 std::uint32_t startBit,
                                 std::uint32_t length,
                                 std::uint64_t &value);
 
    static std::int64_t SignExtend (std::uint64_t value, std::uint32_t bitLength);
};
 
#endif /* DBC_DECODER_H */