Closes #10

core/dbc_decoder.cpp

@@ -39,6 +39,19 @@ DecodedFrameValue DbcDecoder::Decode(const DecodeDatabase &database,
     result.definition = definition;
     result.valid = true;
 
+    const DecodeSignal *selector = nullptr;
+    std::size_t selectorCount = 0U;
+    for (const DecodeSignal &signal : definition->signals) {
+        if (signal.multiplexing.role == MultiplexRole::Selector) {
+            selector = &signal;
+            ++selectorCount;
+        }
+    }
+    const bool selectorDefinitionValid = selectorCount == 1U &&
+            selector->valueType == ValueType::Unsigned && selector->length > 0U && selector->length <= 64U;
+    std::uint64_t selectorValue = 0U;
+    const bool selectorAvailable = selectorDefinitionValid && ExtractUnsigned(frame.data, *selector, selectorValue);
+
     for (std::size_t signalIndex = 0U; signalIndex < definition->signals.size(); ++signalIndex) {
         const DecodeSignal &signal = definition->signals[signalIndex];
         DecodedSignalValue decoded;
@@ -46,8 +59,29 @@ DecodedFrameValue DbcDecoder::Decode(const DecodeDatabase &database,
 
         decoded.definition = &signal;
 
+        if (signal.length == 0U || signal.length > 64U ||
+            (signal.multiplexing.role != MultiplexRole::Unconditional && !selectorDefinitionValid)) {
+            result.signals.push_back(decoded);
+            continue;
+        }
+        if (signal.multiplexing.role == MultiplexRole::Branch) {
+            if (selector->length < 64U && signal.multiplexing.value >= (std::uint64_t(1U) << selector->length)) {
+                result.signals.push_back(decoded);
+                continue;
+            }
+            if (!selectorAvailable) {
+                decoded.status = SignalDecodeStatus::SelectorUnavailable;
+                result.signals.push_back(decoded);
+                continue;
+            }
+            if (signal.multiplexing.value != selectorValue) {
+                decoded.status = SignalDecodeStatus::Inactive;
+                result.signals.push_back(decoded);
+                continue;
+            }
+        }
         if (!ExtractUnsigned(frame.data, signal, unsignedValue)) {
-            decoded.valid = false;
+            decoded.status = SignalDecodeStatus::InsufficientPayload;
             result.signals.push_back(decoded);
             continue;
         }
@@ -58,12 +92,13 @@ DecodedFrameValue DbcDecoder::Decode(const DecodeDatabase &database,
             decoded.rawValue = unsignedValue;
 
         double numericValue;
-        if (const auto *signedValue = std::get_if<std::int64_t>(&decoded.rawValue))
+        if (const std::int64_t *signedValue = std::get_if<std::int64_t>(&decoded.rawValue))
             numericValue = static_cast<double>(*signedValue);
         else
             numericValue = static_cast<double>(std::get<std::uint64_t>(decoded.rawValue));
         decoded.physicalValue = numericValue * signal.factor + signal.offset;
         decoded.valid = true;
+        decoded.status = SignalDecodeStatus::Valid;
 
         result.signals.push_back(decoded);
     }