Added decoding support to runtime decode.

dbc_decoder.h

@@ -0,0 +1,99 @@
+#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 */